CA1088523A - Process for the preparation of low molecular weight polyhydroxyl compounds - Google Patents

Process for the preparation of low molecular weight polyhydroxyl compounds

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CA1088523A
CA1088523A CA285,691A CA285691A CA1088523A CA 1088523 A CA1088523 A CA 1088523A CA 285691 A CA285691 A CA 285691A CA 1088523 A CA1088523 A CA 1088523A
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formaldehyde
reaction
compounds
molecular weight
catalyst
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French (fr)
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Edgar Mohring
Hanns P. Muller
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Bayer AG
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Bayer AG
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/132—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group
    • C07C29/136—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH
    • C07C29/14—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH of a —CHO group
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/132—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group
    • C07C29/136—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH
    • C07C29/14—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH of a —CHO group
    • C07C29/141—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH of a —CHO group with hydrogen or hydrogen-containing gases
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/132—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group
    • C07C29/136—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH
    • C07C29/143—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH of ketones
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/132—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group
    • C07C29/136—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH
    • C07C29/143—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH of ketones
    • C07C29/145—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH of ketones with hydrogen or hydrogen-containing gases
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/36—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring increasing the number of carbon atoms by reactions with formation of hydroxy groups, which may occur via intermediates being derivatives of hydroxy, e.g. O-metal
    • C07C29/38—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring increasing the number of carbon atoms by reactions with formation of hydroxy groups, which may occur via intermediates being derivatives of hydroxy, e.g. O-metal by reaction with aldehydes or ketones
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
    • C07C45/27—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation
    • C07C45/32—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen
    • C07C45/37—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of >C—O—functional groups to >C=O groups
    • C07C45/38—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of >C—O—functional groups to >C=O groups being a primary hydroxyl group
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
    • C07C45/61—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups
    • C07C45/67—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton
    • C07C45/68—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton by increase in the number of carbon atoms
    • C07C45/72—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton by increase in the number of carbon atoms by reaction of compounds containing >C = O groups with the same or other compounds containing >C = O groups
    • C07C45/75—Reactions with formaldehyde
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/30—Low-molecular-weight compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/30—Low-molecular-weight compounds
    • C08G18/32—Polyhydroxy compounds; Polyamines; Hydroxyamines
    • C08G18/3203—Polyhydroxy compounds
    • C08G18/3206—Polyhydroxy compounds aliphatic
    • C08G18/3209—Aliphatic aldehyde condensates and hydrogenation products thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G6/00—Condensation polymers of aldehydes or ketones only
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/04—Oxygen-containing compounds
    • C08K5/05—Alcohols; Metal alcoholates
    • C08K5/053—Polyhydroxylic alcohols

Abstract

ABSTRACT OF THE DISCLOSURE
A process is disclosed for preparing mixtures of low molecular weight polyhydroxyl compounds and hydroxyaldehydes and hydroxyketones by condensing formaldehyde hydrate with itself in the presence of (I) as catalyst, a soluble or insoluble compound of a metal of the 2nd - 4th main or the 1st-8th sub-group of the Period System of Elements, optionally bound to a high molecular weight carrier, and (II) a cocatalyst prepared by partial oxida-tion of a divalent or higher valent alcohol containing at least 2 adjacent hydroxyl groups and having a molecular weight of between 62 and 242 or of a mixture of such alcohols. The pH of the reaction mixture is held at 6.0 to 9.0 until 5 - 40% conver-sion has occurred and is then lowered to between 4.5 and 8.0 (1 to 2 pH units lower). The reaction is stopped by inactivating the catalyst.

Description

10~8~3 PROCESS FOR THE PREPARATION OF LOW MOLECULAR
WEIGHT POLYHYDROXYL COMPOUNDS

BACKGROUND OF THE INVENTION

Polyhydroxyl compounds have become of great commercial importance in various fields. They are used, for example, for the manufacture of non-ionic surface-active compounds, as anti-freezes, moisturizers and softeners, and as starting components for synthetic resins such as polyester and ~olyether resins on a larqe industrial scale.

Polyhydric alcohols are at present obtained from naturally occurring substances such as sugar or cellulose materials or synthesized by the oxidation of petroleum deriva-tives.

In view of the world food situation, it is undesirable lS to use naturally occurring substances as raw materials for industrial products, if they can serve as carbohydrate supplies for nutrition. On the other hand, due to the shortage of petroleum resources, the price of products based on petroleum is constantly rising. Moreover, there are many uncertainties regarding the long-term supply of petroleum products~ It would, therefore, be desirable to find manufacturing processes for s~ polyhydroxyl compounds based on raw materials which are indepen-:,, ~; dent both of naturally occurring substances and of petroleum.

S Since the work of Butlerow and ~oew (Ann. 120, 295 ~; 11861) and J.pr.Chem. 33, 321 (1836)) in the pre~ious century, it has been known that hydroxyaldehydes and hydroxyketones are formed in the condensation of formaldehyde hydrate Ithe term ~ .
/~ "condensation of formaldehyde" will always be used hereinafter .
j,`~

. ~ .

10~5;~3 to mean "condensation of formaldehyde hydrate with itselfn) ur-der the influence of basic compounds such as calcium hydroxide or lead hydroxide. Since formaldehyde can be obtained from coal or natural gas by way of methanol, this would, in theory be a way of obtaining hydroxyl compounds without using petroleum. These hydroxyl compounds could then be used for the synthesis of poly-hydric alcohols by electrolytic reduction or catalytic or chemical hydro~enation.

However, in spite of many proposals to synthesize polyhydroxyl compounds by condensation of formaldehyde, no suitable commercial process has yet been developed for achieving this object because it has not hitherto been possible to synthesize mixtures of polyhydroxyl compounds having a clearly specified and reproducible hydroxyl functionality. Moreover, the known processes give rise to mixtures of hydroxyaldehydes and hydroxyketones which are very difficult to hydrogenate and even then only with very large quantities of catalyst. Due to this high consumption of catalyst, it has up to now geemed to be uneconomic to synthesize polyhydroxyl compounds by condensation of formaldehyde hydrate. This has prevented the reaction to be used condensation/o~ tormaldehyde hydrate/as a basis for a commercial process for the synthesis of polyhydric alcohols.

Due to the disproportionating reaction of formaldehyde to methanol and formic acid which takes place at the same time,
2$ only moderate yields have hitherto been obtaina~le ~y the known processes. Isolation of the end products from the aqueous or aqueous/alcoholic solutions obtained was, therefore, very expensive.

LeA 17,796 -2-10~8S;~3 It is well known that the disproportion3tion o~
formaldehyde into methanol and formic acid is powerfully catalyzed by basic compounds. AS stated by Pfeil in Chemische Berichte 84, 229 (1951), the reaction velocity of this so-called Cannizzaro reaction depends on the square of the formaldehyde concentration while the reaction velocity of formaldehyde poly-addition (C-C linkage) depends directly on the formaldehyde concentration (Pfeil and Schroth, Chemische Berichte 85, 303 (~952)). With increasing aldehyde concentration, therefore, the ratio of the desired polyhydroxyl compounds to methanol and formic acid shi~ts in the direction of the unwanted compounds.
In most of the processes known in the art, it is, therefore, proposed to carry out the condensation of formaldehyde to hydroxyaldehydes and hydroxyketones in solutions which have a 1~ low formaldehyde concentration in order to keep the ~uantity of by-products as low as possible. However, the water used as solvent must then be removed by distillation in order to recover the hydroxyaldehydes and hydroxyketones formed in the process.
This involves high energy costs because of the heat required for evaporation of the water. Processes for the condensation of formaldehyde from dilute aqueous solutions are not, therefore, economical. Moreover, if distillation is prolonged, the hydroxy-aldehydes and hydroxyketones formed undergo considerable decomposition and discoloration reactions.
~, ~ 25 It would, therefore, be desirable to carry out the , condensation of formaldehyde from the usual commercial con-centrated formalin solutions without the appearance of unwanted side reactions. A process for the preparation of aliphatic .,, hydroxyaldehydes in which a 40 ~ formalin solution is reacted with thallium or thallium hydroxide has been described in German LeA 17,796 -3-1~8523 Patent Specification 822,385, but this process is undeslrable because of the toxicity of thallium and thallium hydroxide and the fact that it is difficult to obtain. Moreover, the yields of this process are relatively low, being only 70 to 80 ~.

It has also been proposed to prevent the Cannizzaro reaction by reacting formaldehyde solutions with calcium or lead hydroxide in the presence of methanol, ethanol or other polar organic solvents, and this is described in German Patent Specification 830,951 and Gorr and Wagner, Biochemische Zeitzchrift, 262, 361 (1933).

This addition of organic solvents, however, reduces the formaldehyde content of the solution. The additional energy costs re~uired for evaporating the additional solvent to isolate the hydroxyaldehydes and ketones would, therefore, indicate that this process is also uneconomical. Moreover, formaldehyde and lower alcohols react to form unstable semiacetals which decom-pose during the condensation process, with the spontaneous liberation of the alcohols. Dblays in boiling which occur if the condensation reactions are carried out at reaction temperatures above the boiling point of the alcohol give rise to violent phenomena, particularly in large reaction `:
; batches.under the8e conditions the condensation proce~so~nnot Y;~ be carri~ out on a commercial 8cale without danger.

A process for the preparation of oxy-oxo compounds in which aqueous formaldehyde solutions at concentrations of up to 30 % are reacted with lead oxide or lead acetate and inorganic bases to form sugar-like compounds which reduce Fehling's solu-tion in the cold has.been described in German Patent Specifica-tion 884,794. In ~his process, however, the formaldehyde ' ~

LeA 17,7~6 _4_ - 10~5z3 about solution must be heated for /7 to 8 hours. The volume/ti~ne yield is, therefore, not at all satisfactory. The relatively low yields, of approximately 80 ~, based on the quantity of formaldehyde put into the process, are uL~aati~factory,-voo.

A process for the preparation of hydroxy aldehydes and hydroxyketones has been disclosed in U. S. Patent 2,224,910, in which the exothermic condensation of formaldehyde i8 regulated by the controlled addition of inorganic or organic bases to a formaldehyde solution containing lead, tin, calcium, barium, magnesium, cerium or thorium compounds as well as a compound which is capable of enediol formation, such as glucose, a~corbic acid, fructose, benzoin, glycol aldehyde, erythrose, reductose, invert sugar or condensation products of formaldehyde. Although this process makes it possible for a mixture of hydroxyaldehydes and hydroxyketones to be obtained from relatively highly con-centrated formaldehyde solutions without the addition of organic solvents, it involves various disadvantages. If the reaction is carried out at a low pH, the reaction product consists mainly of hydroxyaldehyde and hydroxyketone mixtures which have a low hydroxyl functionality. Moreover, only moderate reaction velocities are obtained at low pH values, so that the volume~
time yields of this variation of the process are not satisfactory.
: ~o overcome these disadvantages, it i8 recommended in the cited 2S Patent Specification to start the formaldehyde conden~ation reaction at low pH values and then complete it at hi~her pH
values. However, at pH values at or above 7, lead catalyzed .~
formaldehyde condensation proceeds 80 rapidly, spontaneou~ly : and uncontrollably that it i~ impossible to obtain mixture~ of hydroxyaldehydes and hydroxyketones with a reproducible ~:`
~ - LeA 17,796 _5_ 10~3 distribution of components by this process because the reaction times and conditions can no longer be accurately controlled.
Furthermore, it is known that hydroxyaldehydes, hydroxy~etones and monosaccharides decompose in an alkaline medium at elevated temperatures to dark colored compounds partly containing carboxyl groups.

These decomposition reactions occur particularly in those methods descri~ed in U. S. Patent 2,224,910 which are suggested as preferred variations, and they occur to the qreatest extent when most of the formaldehyde has already reacted.
Hydroxyaldehyde and hydroxyketone mixtures prepared according to the process of U. S. Patent 2,224,910, therefore, contain decomposition products with acid groups, are brown in color and cannot be obtained reproducibly. Since the cocatalyst compounds, glycol aldehyde and glyceraldehyde, which are known to be particularly active, are difficult to obtain and are unætable (formation of dark colored decomposition products) and are, therefore, expensive, the method according to U. S. Patent 2,224,910 using these cocatalysts is not advantageous from an economic point of view.

In addition the product mixtures obtained by the procedure described above must always be processed by distilla-tion for purification and for recovering hydroxyl compounds with a low molecular weight. It would be desirable to dispense 2~ with the distillative working up of the mixture, which involves additional consumption of energy and cost of apparatus, and to prepare the product mixtures in such a way that they could be used without further di~tillation as 500n as the water of solution has been removed. However, such colorless reaction LeA 17,796 -6-10~85;~

mixtures substantially free from by-products cannot be obtained by processes known in the art.

It is, therefore, an object of the present invention to provide a process for synthesizing mixtures of polyhydroxyl compounds which are as far as possible free from decomposition products and which can easily be hydrogenated to polyhydric alcohols with small quantities of hydrogenation catalysts. The mixtures of polyhydroxyl compounds obtained should be colorles~
and require no further purification.

It is also an object of this invention to control the conden-sation of formaldehyde so that the molecular distribution of low molecular weight polyhydroxyl compounds in the resulting mixtures can be varied as desired and obtained reproducibly.

DESCRIPTION OF THE INVENTION

It was surprising and completely unexpected to find that mixtures of hydroxyaldehydes, hydroxyketones and of poly-hydric alcohols wbich are free from reducing groups, in which mixtures the proportion of polyhydric alcohols (produced by crossed Cannizzaro reaction) is preferably from 30 to 75~ by weight, can be prepared with excellent volume/time yields if the condensation of formaldehyde hydrate is carried out in the ',?j~; presence of soluble or insoluble metal compounds, preferably lead, tin, calcium, barium, magnesium,~cerlum or thorium com-- pounds, which compounds are used as catalystS/Qptionally bound to a high molecular weight catalyst carrier, as well as in the presence of a cocatalyst consisting of a mixture of compounds ~; capable of enediol formation, which cocatalyst is obtained by partial oxidation of one or more dihydric or higher hydric , :

LeA 17,796 -7-. ~

1~8SZ3 alcohols which have at least two adjacent hydroxyl groups and molecular weights of between 62 and 242.

The reaction temperature during the formaldehyde con-densation is generally between 70C and 1200C, preferably between S 90 and 105C, and the pH is controlled by the controlled addition of bases so that it is between 6.0 and 9.0, preferably between 7.5 and 8.5, up to a conversion of the -~tarting materials of from 5 to 40%, preferably from 10 to 20%, and thereafter between 4.5 and 8.0, preferably between 5.5 and 7.5 until termination of the condensation reaction, so that the pH during this phase of the reaction is lower by 1.0 to 2.0 units than in the first phase of the reaction.

The present invention thus relates to a process for the preparation of mixtures of low molecular weight, polyhydric lS alcohols and hydroxyaldehydes and hydroxyketones by the condensa-tion of formaldehyde in the presence of from 0.01 to 10% by weight, based on the formaldehyde, of metal compounds as catalysts and from 0.1 to 10% by weight of cocatalysts based on compounds capable of enediol formation, which process is characterized in that aqueous formalin solutions and/or paraformaldehyde dis-: persions containing from 20 to 65% by weight of formaldehyde are condensed at a reaction temperature of from 70 to 120C, preferably 90 to 105C, in the presence of (I) a soluble or insoluble compound of a metal of the 2nd to the 1st to 8th Z5 4th Main orlsub-Group of the Periodic System of Elements, optionally bound to a high molecular weight carriar, and II) a cocatalyst prepared by par~tial oxidation of a dihydric J~ or higher hydria alcohol containing at least two OH groups ?~
adjacent to each other and having a molecular weight of :~ 30 between 62 and 242 or a mixture of such alcohols.
;~
~: LeA 17,796 -8-10~5;~3 The pH of the reaction solution is maintained at between 6.0 and 9.0, preferably between 7.5 and 8.5 by controlled addition of an inorganic and/or organic base up to a conversion rate of the starting materials of from 5 to 40~, preferably 10 to 20~, and thereafter at between 4.5 and 8.0, preferably between 5.5 and 7.5 until termination of the condensation reaction. In this -~econd phase of the reaction the pH i~ lower by 1.0 to 2.0 units than in the first phase of the reaction. The reaction i9 stopped when the residual formaldehyde content is from 0 to 10% ~y weight, preferably from O.l to 6~ by weight, by the addition of acid to inactivate the catalyst. The catalyst is then removed, preferably by precipitation reactions or by cathodic electro-chemical deposition, and the aldehyde and keto groups in the reaction product are optionally reduced to hydroxyl groups.

It is known to reduce hydroxyaldehydes and hydroxy-ketones with formaldehyde. Thus. for example, pentaerythritol dehvde can be synthesized from acetal/and formaldehyde, the acetalde-hyde being first methylolated to pentaerythrose and then reduced with excess formaldehyde. Such crossed Cannizzaro reactions can only be carried out in a strongly alkaline medium.
It was, therefore, extremely surprising to find that in the new process, this reduction proceeds to yields of from 30 to 75~, both in a weakly alkaline medium and in a slightly acid medium.
This reduction advantageously already reduces a high proportion o~ the carbonyl groups, thereby considerably simplifying the subsequent removal of the remaining carbonyl groups by hydrogena-;~ tion or reduction.

It was also surprising to find that the reaction carried out according to the invention result~ in highly concentrat~d aqueous solutions of hydroxyaldehydes and hydroxyketones which LeA 17,796 -9-lO~SZ3 are colorless. Therefore, no further purification or decoloriza-tion is required unlike the proce~ges known in the art where undesirable, strongly colored by-products are formed due to decomposition reactions. The removal of these by-products i~
very difficult if not impo~sible. Moreover, these strongly colored solutions obtained by the known art proce~ses are impossible or at least very difficult to hydrogenate to poly-hydric alcohols and only low yields can be obtained.
The colorless reaction mixtures obtained according to the inven-tion, however, are able to undergo catalytic hydrogenation under the mild conditions normally employed for the catalytic hydrogena-tion of sugars. This is done after removal of the (condensation) catalyst by simple precipitation reactions or electrochemical deposition.

In the process according to the invention, glycol aldehyde is first formed from two molecules of formaldehyde-hydrate in a primary reaction step. Glyceraldehyde i8 then formed from the glycol aldehyde by further addition of formalde-hydehydrate as represented by the following reaction scheme:

(I) HO-CH2-C ~ + HO-CH2-OH ~ HO-CH2-CH-C ~ + H2O
H OH H

The mixtures of hydroxyaldehyde~ and ketones obtained according to the invention are then formed from glyceraldehydo by numerous subsequent reactions, somo of which are shown belo~
~.
by way of example:

(II) HO-CH2-CH-C + HO-CH2-C ~ HO-CH2-CH-CH-CH-C ~
OH OH OH OH H

LeA 17,796 -10-10~85~3 O HO-CH2 .
(III) HO-CH2-CH-C + HO-CH2-OH --~ HC-CH2-C ~C~ ~2 OH H OH
O O
( IV) HO-CH2-CH-C ~ HO-CH2-C-CH2-OH
OH H
O O
(V) HO-CH2-CH-C +HO-CH2-C-CH2-OH
OH H n OH OH OH
o (VI ) HO-CH2-CH-CH-CH-C-CH2-OH + HO-CH2-OH
OH OH OH

HO-CH2-CH-CH-C C-CH2-OH + H20 OH OH OH

Gas-liquid ckromatography of various product mixture~
prepared according to the invention has shown that the distribu-tion of products obtained by the process according to the .:
invention can be varied by stopping the reaction at various residual formaldehyde contents and that the distribution of ~ 10 products can be adjusted to be completely reproducible both with respect to compounds having from 2 to 4 carbon atoms and with respect to compounds having 5 or more carbon atoms. Th~s was not to be expected in view of the large number of reactions, .~,, ~
only some of which have been mentioned above, which may ta~e ; I5 place simultaneously and side by side in the process accord~ng to the invention.

i ~
~: LeA 17,796 10~3 The condensation of formaldehyde by the process according to the invention is preferably carried out with aqueous formaldehyde solutions at commercial concentrations (30 to 50~ by weight formaldehyde) stabilized with methanol or other known stabilizers. However, unstabilized formaldehyde solutions containing a proportion of solid, polymerized formaldehyde and/or paraformaldehyde dispersions may also be used since these solid constituents are dissolved by depoly-merization during the process according to the invention and can then also be condensed to hydroxyaldehydes and hydroxyke-tones. Even more highly concentrated formaldehyde solutions, such as those obtained by depolymerization of paraformaldehyde or by concentration of dilute formaldehyde solutions by evapora-tion under vacuum, can also be condensed by the process according to the invention. For example, hydroxyaldehydes and hydroxyketones can be obtained in very high yields by condensa-tion of a 65% formaldehyde solution which has been obtained by evaporating a 37~ formaldehyde solution under vacuum.
The process according to the invention may, of course, also be applied to less highly concentrated formaldehyde solu-tions but these more dilute formaldehyde solutions are less desirable from an economic point of view on account of the additional energy costs required for evaporation of the solvent.

Hydroxyaldehydes and hydroxy~etones are formed extremely rapidly in the process according to the invention.
- After a reaction time of 15 minutes, for example, about 80% of the formaldehyde put into the process have generally undergone reaction. After 20 minutes the formaldehyde content of the solution is generally reduced to 1 to 1.5%, which corresponds to a conversion of 96 to 97%. The volume/time yields of the LeA 17, 796 -12-~0~ 3 process according to the invention are, therefore, ~up~rior to those of all known processes for the preparation of hydroxy-aldehydes and hydroxyketones by conden~ation of formaldehyde.
Compared with the processes mentioned in German Patent 884,794, for example, the volume/time yield i~ greater by a factor of 25 to 50.

According to the invention, the conden~ation of formaldehyde to form hydroxyaldehydes and hydroxyketones is preferably catalyzed by water-soluble compounds of lead, in particular lead(II) acetate, lead(II) formate and lead~II) nitrate. Since commercial formaldehyde solutions are normally slightly acid in reaction, water-insoluble lead compounds such as lead(II) carbonate, lead(II) oxide, lead(IV) oxide and lead(II) hydroxide and Pb(II) salts or Pb(IV) salts of oxalic acid, phenol, thiophenol or salicylic acid may also be used as the catalyst.

The following are examples of other compounds which may also be used as catalysts: Ca(OH)2, CaCO3, CaC12, Ng~OH)2, 2 3 2 ( 3)2' SnC12' Hg(N3)2, CeC13 and Th~NO ) According to the invention, the quantity of catalyst used is approximately 0.01 tô 10% by weight, preferably 0.1 to 5~ by weight, based on the quantity of formaldehyde put into the process.

If, as is paxticularly preferred according to the invention, lead(II) salts are used as cataly~t, the Pb~II) ion~
are gsnerally removed by precipitation with carbonate ion~
before the reaction products are processed or hydrogenated.

j:.
. ~

~ LeA 17,796 -13-10~8S;~3 It is particularly advantageous, and very desirable for environmental reasons, that these precipitated lead salts can be used again as catalyst, either as such or by conversion to the acetate. The ecologically potentially harmful waste products resulting from the processes known in the art are thus avoided in the process according to the invention. The proce~s is, therefore, superior to the known processes both on ecologi-cal and on economic grounds in view of the recycling of the lead catalyst.

The lead(II) ions used as catalyst can also be removed as elementary lead by electrolytic cathodic deposition. In that case, again, the lead can be returned to the production proceQs as catalyst, for example by ~onversion into the acetate or by anodic oxidation accompanied by qolution.

The lead(II~ ions can also be removed from the reac-tion solution quite simply by pumping the solution over cation active ion exchangers. Analysis by atomic absorption shows that no lead can be detected in reaction solutions which have been treated in this way.

2~ Ion exchangers which have become partly or completely charged with lead in the process of removal of lead from the reaction solution and ion exchangers which have been deliberately charged with lead ions by application of lead salt solution can also be used as catalysts for the conden8ation of formalde-hyde under the conditions of the process according to the ~ invention. It has been found that the8e le8d-charged ion -~ exchanger resins (e.g., the known sulphonated polystyrene -~ ~ resins cro~s-linked with divinyl benzene or cro8s-linked acrylic acid resins or modified formaldehyde urea derivatives) .
LeA 17,796 -14-lOW5~

are equally successful in catalyzing formaldehyde conden~ation as the soluble lead salts themselves. It is particularly advantageous that the quantities of lead used in these ion exchangers can be much smaller than the quantities required in the known processes. It is also advantageous that these lead charged ion exchangers can be obtained directly by the removal of salt from the reaction solution and used again for the removal of salt after they have been used as catalysts.

According to a particularly advantageous embodiment of the process according to the invention, the following pro-cedure is adopted: A certain quantity of lead charged ion exchanger resin, depending on the ~uantity of reaction mixture - used, is added as solid catalyst to the reaction solution.
Lead ions are given off to the reaction solution during the reaction, so that the solid catalyst is gradually depleted of lead ions. After termination of the reaction, the ion exchanger is removed by suction filtration and the reaction solution i5 ~ freed from lead by passage over an ion exchanger which i8 not : charged or only partly charged with lead. After repeated use, that part of the ion exchanger resin which was used as solid ~; catalyst is so severely depleted of lead ions that its catalytic activity is slightly reduced.

The other part of the ion exchanger resin, which was used for removing the lead from the solution, is now heavily charged with lead ions. When both parts of the exchanger resin have been rinsed with water, that part which was used for removal of the lead from the reaction solution is used as catalyst and the other part, which is now no longer charged completely with l¢ad, is used for removing the lead ions from the reaction mixture.

LeA 17,796 -15-10~85Z;~

In this way, the lead required for catalysis can be completely utilized without repeated use of fresh lead sa:.ts or formation of harmful waste products. This variation of the process is, therefore, particularly important for both economic and ecological reasons.

What has been said about lead compounds i8, of course, applicable in a similar manner to compounds of other metals used as catalyst.

According to another particularly si~ple method, the catalyst metal, in particular lead, can be used repeatedly for the condensation process. The metal ions are deposited electrolytically on a metal cathode after formaldehyde condensa-tion has been stopped by the addition of acid. The reaction chamber is then emptied, fresh formalin solution is introduced, and the polarity of the current is reversed so that the electrode previously functioning as cathode becomes the anode. Electroly-sis is started again so that the lead deposited as metal on the electrode which is now the anode is reconverted into lead ions by anodic oxidation and goes into solution. This process can be repeated indefinitely since no lead is lost.

One particular feature of the process according to the invention is the use of a special cocatalyst.

It is kno~n from the literature that compounds which contain enediol groups or compounds which are capable of enediol formation in accordance with the following equation:

, ~:~

LeA 17,796 -16-lO~B523 2 ~ Rl-C = C-R2 ~ OH OH

in which Rl and R2 which may be the same or different represent hydrogen, alkyl, hydroxyalkyl or aryl groups, can be used as cocatalysts for formaldehyde condensation.
According to U. S. Patent 2,224,910, the compounds used for this purpose are mainly glucose, ascorbic acid, fructose, benzoin, glycol aldehyde, erythrose, reductose and invert sugar. The cocatalysts are intended to eliminate the induction period at the beginning of formaldehyde condensation, but most of these cocatalysts only develop their catalytic activity at pH values ~ 7. At this pH range, the disproportionation of formaldehyde leading to unwanted by-products and reduction in yield is intensi-fied. Other cocatalysts can only be prepared by complicated lS methods of synthesis and are, therefore, expensive.

The most suitable cocatalysts, glycol aldehyde and glyceraldehyde, are very difficult to obtain and unstable in storage ( formation of dark colored decomposition products) ~ and, therefore, expensive and unsuitable on economic grounds.
,~
~:
`~ 20 It has now surprisingly been found that the con-densation of formaldehyde hydrate without inhibition at the beginning o~ the reaction will proceed at pH values below 7 as well as above 7 substantially without a Cannizzaro reaction if, ~-.`r~
~` according to the invention, mixtures of products which have 25 been prepared by partial oxidation of dihydric or higher hydric alcohols or alcohol mixtures having at least two hydroxyl groups on adjacent carbon atoms and which contain, inter alia, hydroxy-`~ aldehydes, hydroxyketones and hydroxy acids in addition to ;,:
:, LeA 17,796 -17-10~S;~3 unoxidized (catalytically inactive) polyhydric alcohols are used as cocatalysts.

It is immaterial whether oxidation of the polyhydric alcohols takes place in a completely separate reaction step or immedia~ely before the condensation reaction according to the invention or even later, in the reaction mixture itself.
However, for practical reasons it is preferred to carry out this oxidation reaction during the passage of the reactants to the reaction vessel for formaldehyde condensation. Most preferably, it is carried out in situ in the aqueous formalde-hyde solution. It is extremely surprising to find that sufficient quantities of cocatalysts are formed in this last mentioned variation of the process. Owing to the readiness with which formaldehyde oxidizes (it may be remembered here that formalde-hyde is commonly determined by its reaction with E~2O2:
2HCHO + H202 + 2 NaOH = H2 + 2HCOONa + 2H20) it was to be assumed that the oxidizing agent would only react to a very minor extent, if at all, with the polyhydric alcohol to form hydroxyaldehydes, ketones, carboxylic acids, etc. and would attack mainly the concentrated formaldehyde.

The reaction mechanism of the process according to the invention and the mode of action of the cocatalyst are still to a large extent unknown. This applies particularly to the initial phase of the condensation reaction, in which the accelerating action of the catalyst/cocatalyst system according to the invention is particularly important. However, it may be assumed, without this assumption in any way restr~cting the scope of protection of the present invention, that the hydroxy-aldehyde ~or hydroxyketone) formed in a first stage of the process from a polyhydric alcohol i8 not solely re~ponsible LeA 17,796 -18-10~85~

for the catalytic effect. This follows partly from the fact that aldehyde functional groups are much ~or~ readily oxidized ~han hydroxyl groups. Thus, in the case of partial oxidation of poly-hydric alcohols, only very small quantities of hydroxyaldehydes are ever formed in addition to the main product, which consists of hydroxycarboxylic acids.M~re ~ rom t~e observation that when a hydroxyaldehyde (e.g. glycol aldehyde or glyceraldehyde), alone or as mixture with a corresponding polyalcohol, i~ used as cocatalyst for the condensation of formaldehyde, it only give~
rise to the formation of quite unsatisfactory, brownish products.
It is more likely, although surprising, that the hydroxy carboxylic acids act as cocatalyQts, either alone or as syner-gistic combinations with the traces of hydroxyaldehydes and/or ketones present or possibly also with the unoxidized polyols present.

The quantity of polyhydric alcohol or alcohol mixture to be used according to the invention may vary within wide limits. In many cases, for example, 1% by weight of alcohol, based on the quantity of formaldehyde put into the process, is capable of producing entirely sufficient quantities of cocatalyst.
:.
~- However, it is advantageous to use larger quantities, approxi-mate~y ~ ~to 10% by weight, based on the formaldehyde, of poly-hydric alcohol or alcohol mixture. This iæ particularly true `~ if oxidation i9 carried out in situ, so that right from the beginning of formaldehyde condensation sufficient oxidation products of these alcohols will be formed and will be available .~
as cocatalyst.

The quantity of polyhydric alcohol or alcohol mixture ~ used should generally not fall below the lower limit of 0.001 OH

.,~ ,, ~ LeA 17,796 -19-equivalents, based on l mol of formaldehyde put into the process, because the cocatalytic activity is then too weak. In theory, no upper limit need be set although for practical reasons it is preferable not to use more than 500 OH equivalents.
It is preferred that an amount of the polyols which corres- re ponds to 0.001 to 0.1 OH equivalents (based on 1 mol of formaldehyde)is present in the reaction mixture in partly oxydised,i.e. co-catalytically active form.
The upper limit on the quantity of oxidizing agent to be used is set by the quantity of polyhydric alcohol or alcohol mixture present since only the partially oxidized ~to hydroxy-aldehydes, ketones and carboxylic acids) alcohols act as cocatalyst (see above). By "partially oxidized" is meant, in the context of this invention, that not more than 85%, pre- -ferably less than 70% and most preferably less than 50% of all the hydroxyl groups in the polyhydric alcohol are oxidized.
According to the invention, one may, of course, use slightly more than the maximum quantity of oxidizing agent theoretically calculated from these figures since part of the oxidizing agent is lost by its reaction with formaldehyde, particularly in the preferred variation of the process, in which the cocatalyst is formed in situ. However, there should not be used more oxidiz-ing agent than the quantity theoretically calculated for the oxidation of all the hydroxyl groups of the polyhydric alcohol to keto or carboxyl groups. Otherwise too many side reactions take place, and the total yield of formaldehyde condensation ; products is reduced.

~ ., As in the case of the alcohol, the quantity of oxidiz-ing agent should not fall below the lower limit of O.OOl equiva-lents of oxidizing agent per mol of formaldehyde becau~e other-wise the proportion of oxidation products which are active as LeA 17,796 -20-lO~S23 cocatalysts becomes too low. It i8 particulsarly pre~erred to use the oxylS;ising agents in an amount of from 0.002 to 0,02 equivalents, based on 1 ~ol of formaldehyde. ThiQ
gives rise to the above mentioned prferred amount of partially oxydised polyols being present in the reaction mixture.
The following are example~ of alcohols which are suitable for preparation of the cocatalyst by partial oxidation, preferably along the mixing path: Propylene glycol-(1,2), butylene glycol-~0(2,3), hexanediol-(2,3) and -(3,4), 2-methyl-1,2-propanediol, butanetriol-(1,2,4), hexanetriol-(1,2,6), erythritol, quinitol, mannitol, sorbitol and methyl glycoside. It is preferred to u~e polyhydroxyl alcohols having at least one primary hydroxyl group but ethylene glycol, glycerol and the reduced sugar alcohol mixtures obtained by crossed Cannizzaro reactions in formalde-hyde condensations are particularly preferred.

~;~ Any known oxidizing agents for alcohols may be used for the partial oxidation of the above-mentioned dihydric or higher hydric alcohols, or mixtures thereof, which have at ~ 20 least two adjacent hydroxyl groups. The following are example_ of suitable oxidizing agents: Compounds of divalent copper, e.g.
copper(II) nitrate; compounds of trivalent iron, e.g. iron(III) chloride and potassium hexacyanoferrate(III); compounds of mono-valent silver, e.g. silver(I) oxide: compounds of tetravalent or heptavalent manganese, e.g. manganese dioxide or potassium permanganate; compoundQ of pentavalent vanadium, e.g. divanadium pentoxide; compounds of hexavalent chromium, e.g. chromium tri-. ~ -~ .~
.

`~ Le A 17 796 - 21 -, . , , 10~8523 oxide, chromic acid and sodium or potassium dichromate; seleniu~
dioxide, osmium tetroxide, hydroqen peroxide oxygen compounds of nitrogen, e.g. alkali metal hyponitrite, n~trous acid or its salts and nitric acid or its ~alt~; haloyens and thoir heptava-lent oxygen compounds, e.g. sod~um perlodate or potas~ium perchlorate; inorganic or organic peracids or thoir J~lts, e.g.
sodium pyrosulphate, ammonium peroxy disulphate, peracetic ~cid and perbenzoic acid also oxygen or air. Readily available ,,~ -`'"i' ' ~

,~, Le A 17 796 -21 a -:"~
::~
'':

1088~3 oxygen containing compounds such ag nitric acid, hydrogen peroxide or chromic acid are preferably used.

Potassium permanganate and lead(IV) oxide (which acts both as oxidizing agent and as catalyst) are particularly pre-ferred. Anodic oxidation is also possible.

As already mentioned above, it is theoretically possible to prepare the cocatalyst separately by partial oxida-tion of the polyhydroxyl compound and then to add it to the reaction mixture in the desired quantity. In many cases, however, the partially oxidized polyhydric alcohols are not stable in storage and tend to undergo reactions which cause brown dis-coloration. For this reason, and for reasons of simplicity, it is preferable to combine the polyhydric alcohol and oxidizing agent along the mixing path, i.e. immediately before the addition to the aqueous formaldehyde solution or to add the oxidizin~
agent to the previously prepared reaction mixture of formalde-~- hyde solution, polyhydroxyl compound having at least two adjacent hydroxyl groups, and catalyst. Even when oxidation i9 carried ; out in a separate step or along the mixing path, the polyhydric alcohol is preferably oxidized in the presence of the metal catalyst. Presumably, when this method is employed the enediol compounds formed as intermediate products are absorbed by the metal ion by a proce~s of complex formation and thus converted into a catalytically particularly active form.

Tbe condensation reaction proceeds so rapidly in the presence of the cocatalyst according to the invention that improved volume/time yields are obtained, with the attendant advantages already mentioned above. Since the condensation of formaldehyde to hydroxyaldehydes and hydroxyketones proceeds 80 .., `,:
, . .

~ - LeA 17,796 -22-~, .

101~8S;~3 rapidly at temperatures above 95C under the conditions aceording to the invention that the reaction mixture is heated by the heat of reaction liberated, the reaction solution need only be heated externally to temperatures from 90 to 100C, and the external source of heat may then be removed. The quantities of heat liberated by the exothermic reaction are -~o great that the reaction solution is easily kept at boiling point during the whole reaction time. At the same time, the reaction velocity is still sufficiently low within the given pH range to allow the reaction to be stopped at any time by external cooling or by the addition of acids if this is desirable for obtaining a particular residual formaldehyde content or distribution of products. The pH control as carried out according to the invention also com-pletely supresse~ the formation of strongly colored decomposi-tion products.

Inorganic bases suitable for the process according to ~; the invention include, for example, NaOH, KOH, CaO, Ca(OH)2, -~ MgO and Mg(O~)2. Urotropine, pyridine, secondary and tertiaryamines and so-called "crown ether complexes" of alkali metals are examples of suitable organic bases.

Higher molecular weight polyols, hydroxyaldehydes and hydroxyketones (particularly with 5 and with 6 carbon atoms) are obtained without undesirable colored by-products by the process according to the invention, if the reaction is continued to a residual formaldehyde content of from 0 to 1.5~ by weight and then stopped by cooling and~or by inactivation of the ~` ~ catalyst. The product mixtures obtained in this way are sub-stantially free from formaldehyde.
'~:

:`

~ LeA 17,796 -23-case It is surprisingly found that alao in this/
by controlling the reaction conditions in accordance with the invention and using the cocatalysts defined above the unwanted Cannizzaro reaction of formaldehyde (disproportionation into methanol and formic acid), which reduces the formation of hydroxyaldehydes and ketones,may be minimized and no reaction~ which cau8e brown di~coloratlon t~ke p~a~e According to gas chromatographic analysis of the hydrogenated and silylated reaction products, in the above-mentioned preferred variation of the proce3s according to the invention, in which the reaction i8 continued to a residual formaldehyde content of from 0 to 1 5~ by weight, approximately 45% by weight of hexavalent alcohols, 2S% by weight of penta- -~lS valent alcohol~ and approximately 20% by weight of heptavalent and higher valent alcohols are formed The total amount of .. ,. ~ . , ~
divalent, trivalent and tetravalent alcohols formed amounts to only about 10%

The prQcess according to the invention i~ not 20~ re~tricted to the preparation of mixtures of hydroxyaldehydes and~hydroxyketones and polyhydric alcoholQ with a predominant proportion of hiqher functional compounds As alreàdy m ntioned above, the distribution of products can be varied according to `the~in~ention by` continuin~ tha condèn~ation reaction~to a certaln residual formaldehyde content and then stopping ~t, far~ex~mple, by cooling If, for example, the condensation r~act~ion is only continued to the stage where the ~olutlon ~tiil ains 8% by we~qht of free formaldehy~e and t~e~reaction mlxture is then cooled, practically no compounds ha~ing 8iX or ~.

~ ~ LeA 1?,796 -24-.~ .
,~.

10~8523 more carbon atoms are found in the product mixture obtained but the proportion of compounds which contain two hydroxyl groups after reduction is increased to 16% by weight, the proportion of compounds having three hydroxyl groups in the reduced form is increased to 20% and the proportion of compounds having four hydroxyl groups in the reduced form is increased to 30S.

Various distributions of products can thus be obtained according to the invention by continuing the condensation of formaldehyde to residual formaldehyde contents varying from 8%
to 1.5%. Any desired distribution of products necessary for a given field of application can thus be obtained.
As already mentioned above / it is also possible to use relatively large quantities of monohydric or polyhydric low molecu~r w~i~ht alcoh~ls and/or in the proce8s accordi~g ~o the invention higher molecular weight polyhydroxyl compounds~. This procedure ;15 affords important advantages. Firstly, it considerably facilitates the complete removal of water from the product mixture by evaporation under vacuum. Furthermore, reaction temperatures above 100C may be employed, so that the volume/
~ime yield is improved.

The viscosity of the product is also surpriæingly found to be considerably lower than that of formaldehyde con-densation products produced without the addition of the above-menPtio~e~/comYounds according to the invention. The processing ~ characteristics of the products are thereby substantially 25~ improved. The products obtained according to the invention are ~ compatible with many other start~ng components used for the .~ ~
production of polyurethane resins, particularly foam resins, e.g. polyethers, polyesters and blowing agents. Thi~ is par-ticularly surprising in view of the fact that, when previously ~eA 17,796 -25-10~
known polyols prepared by formaldehyde conden~ation reactions are mixed with blowing agents, flocculation and cloudiness are observed. The miscibility of the individual components can be even further improved in the process according to the invention by adding known emulsifiers, anticoagulants and stabilizers for emulsions, dispersions and suspensions.

Of course, it is also possible according to the inventlon to use ether monohydric and/or polyhydric low molecular weight alcohols and/or high molecular weight polyols in addition to the polyols containing two adjacent OH-groups.
However, as explained above, the total amount of all the hydroxyl compounds should not exceed 500 hydroxyl equivalents, based on 1 mol of formaldehyde.

Examples o~ such low molecular weight alcohols which may optionally be used include alcohols having a molecular weight of between 62 and 400 and having from 1 to 8, preferably 2 to 6, hydroxyl groups which are not ad-jacent to one another. The alcohols are preferably ` liquid at room temerature either on their own or when mixed with formalin solution.

.'b "
'., ' :
i ``'' ~ ~i :
'O'.' ~ ::

e A ~l7 796 - 26 -':

The following are examples of ~ molecular weight alcohols in which condensation of formaldehyde can readily be carried out: 2-Ethoxyethanol; 2-propoxyethanol; 2-isopropoxy-ethanol; 2-butoxyethanol; 2-(2-methoxyethoxy)-ethanol;
2-(2-ethoxyethoxy)-ethanol; 1,2-bis-(2-hydroxyethoxy)-ethane;
, diethylene glycol; triethylene glycol;
tetraethyleneglycol; .; dipropylene glycol;
tripropylene glycol; 1,3-propanediol; ; 1,3-butanediol; 2-methoxy-1-butanol; ; 1,5-pentane-diol; 2,2-dimethyl-1,3-propanediol; 1,6-hexanediol; 2,5-hexanediol; 2-methyl-2,4-pentanediol; 3-methyl-1,5-pentanediol;
3-methyl-2,4-pentanediol; ; 2-methyl-2-propyl-1,3-propanediol; 2,2-diethyl-1,3-propanediol; 2-ethyl-1,3-hexanediol; 2,5-dimethyl-2,5-hexanediol; 2,2,4-trimethyl-1,3-pentanediol; 1,3-diethoxy-2-propanol; 2-hydroxymethyl-~ 2-methyl-1,3-propanediol; . ; 2-ethyl-2-hydroxy-:~ methyl - 1,3-propanediol; 2,2-bis-hydroxymethyl-1,3-propanediol;
, ~- and ethoxylation and propoxylation products of these alcohols with molecular weights of up to 400 and, of course, also ;~ mixtures of these alcohols.
'' ' , ~
. Higher molecular weight polyhydroxyl compo~nds ~hich may be used in addition to polyols containing two ad~acent OH-groups j ,~
~ include those with molecular weights from 400 to 1-0000, pre-~ 25 ferably 500 to 60oo. mese .. ~ ~ .
, ~

,, :
LeA 17,796 -27-10~8523 polyhydroxyl compounds are also preferably liquid at room temperature or soluble in the aqueous formaldehyde ~olution.
They include, for example, polyesters, polyether~, polythioethers, polyacetals, polycarbonates and polye~ter amides having at lea~t 2, generally 2 to 8, preferably 2 to 4 hydroxyl groups, such as the hydroxyl compounds known ~ e for the production of both homogeneous and cellular polyurethanes.

Suitable polyesters with hydroxyl groups include, for example, reaction products of polyvalent, preferably divalent alcohols, to which trivalent alcohols may be added, and polyvalent, preferably divalent carboxylic acids. Instead of free poly-carboxylic acids, the corresponding polycarboxylic acid anhy-drides or corresponding polycarboxylic acid esters of lower alcohols or mixtures thereof may, of course, be used for pre-paring the polyesters. The polycarboxylic acids may be ali-phatic, cycloaliphatic, aromatic and/or heterocyclic and they may be substituted, e.g. by halogen atoms, and/or unsaturated.

The following are mentioned as examples: Succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, .
phthalic acid, isophthalic acid, trimellitic acid, phtalic acid anhydride, tetrahydrophthalic acid anhydride, hexahydrophthalic , ~, acid anhydride, tetrachlorophthalic acid anhydride, endo-methylene tetrahydrophthalic acid anhydride, glutaric acid 1 ~ anhydride, maleic acid, maleic acid anhydride, fumaric acid, .,, ~
~` ~25 dimeric and trimeric fatty acids ~uch a~ oleic acid which may be mixed with monomeric fatty acids, dimethyl terephthalate and terephthalic acid-bi~-glycol esters. The following are example~
of suitable polyvalent alcohols: Ethylene glycol, propylene glycol-(1,2) and -tl,3), butylene glycol-(l,~) and -t2,3), hexane-diol-(1,6), octanediol-(1,8), neopentylglycol, cyclohexane-~, :

~ LeA 17,796 -28-~O~

dimethanol ~1,4-bis-hydroxymethylcyclohexane), 2-methyl-1,3-propanediol, glycerol, trimethylolpropane, hexanetriol-(1,2,6), butanetriol-(1,2,4), trimethylolethane, pentaerythritol, quinitol, mannitol and sorbitol, methylglycoside, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycols, dipropylene glycol, polypropylene glycols, dibutylene glycol and polybutylene glycols. The polyesters may also contain a proportion of carboxyl end groups. Polyesters of lactones such as ~-caprolactone or hydroxycarboxylic acids such as ~-hydroxycaproic acid may also be used.

The polyethers used according to the invention which have at least 2, ~enerally 2 to 8 and preferably 2 to 3 hydroxyl groups are also known E~ se. They are prepared, for example, by polymerization of epoxides such as ethylene oxide, propylene oxide, butylene oxide, tetrahydrouran, styrene oxide or epichlorohydrin, either each on its own, e.g. in the presence of boron trifluoride, or by addition of these epoxides, either as mixtures or successively, to starting components having reactive hydrogen atoms. These starting components include water, alcohols, Emmonia or amines, e.g. ethylene glycol, pro-pylene glycol-(1,3) or -(1,2), trimethylolpropane, 4,4'-dihydroxydiphenylpropane, aniline, ammonia, ethanolamine or ~ ethylene diamine. Sucrose polyethers may also be used according -~ to the invention, e.g. those described in German Auslegeschriften 1,176,358 and 1,064,938. It is in many cases preferred to use polyethers which contain predominantly primary hydroxyl groups;
up to 90% by weight, based on all the hydroxyl groups present in the polyether. Polyethers modified with vinyl polymers, e.g.
the compounds obtained by polymerization of styrene or acryloni-trile in the presence of polyethers ~U. S. Patents 3,383,351;

LeA 17,796 -29-10~85;~3 3,304,273: 3,523,093 and 3,~10,695 and German Patent 1,152,536) are al~o suitable, as well as polybutadienes which have hydroxyl groups.

Particularly suitable among the polythioethers are the condensation products obtained by reacting thiodiglycol on its own and/or with other glycols, dicarboxylic acids, formalde-hyde, aminocarboxylic acidQ or amino alcohols. The product~
obtained are polythio mixed ethers, polythio ether ester~ or polythio ether ester amides, depending on the co-components.

Suitable polyacetals include, for example, the com-pounds which can be prepared from glycols such as diethylene glycol, triethylene glycol, 4,4'-dioxethoxy-diphenyl dimethylmethane, hexanediol and formaldehyde. Suitable poly-acetals for the purpose of the invention may also be prepared by the polymerization of cyclic acetals.

-~ The polycarbonates with hydroxyl groups used may be of the kind known ~ se, for example, those whlch can be prepared by the reaction of diols such as propanediol-(1,3), butanediol-(1,4) and/or hexanediol-~1,6), diethylene glycol, triethylene glycol or tetraethylene glycol with diarylcarbonates, e.g. with diphenylcarbonate or phosgene.

Suitable polyester amides and polyamid~es include, for example, the predominantly linear condensates prepared from pol~yvalent saturated and unsatuxated carboxylic acid~ or their 25~ anhydrides and polyvalent saturated and unsaturated amino a1cohols, diamines, polyamines and mixtures thereof.

Polyhydroxyl compounds already containing urethane or urea ~roups and modified or unmodified natural polyol~ ~uch ~":
- ~ ~
~ ~LeA 17,796 _30_ 10~5;~3 as castor oil, carbohydrates or starch may also be used.
Addition products of alkylene oxides and phenol formaldehyde resins or of alkylene oxides and urea formaldehyde resins are also suitable for the purpose of the invention.

Representatives of these compounds which may be used according to the invention have been de~cribed, for example, in Hiqh Polymers, Vol. XVI, "Polyurethanes, Chemistry and Technology~
by Saunders-Frisch, Interscience Publi~hers, New York, ~ondon, Volume I, 1962, pages 32 - 42 and pages 44 - 54 and Volume II, 1964, pages 5 - 6 and 198 - 199 and in Kunststoff-Handbuch, Volume VII, Vieweq-Hochtlen, Carl-Hanser-Verlag, Munich, 1966, e.g. on pages 45 to 71.

Mixtures of the above-mentioned compounds which contain at least two hydrogen atoms capable of reacting with isocyanates and have a molecular weight of from 400 to 10,000 may, of course, also be used, for example mixtures of polyethers and polyesters.

Polyhydroxyl compounds which contain high molecular weight polyadducts or polycondensates in a finely dispersed or dissolved form may also be used according to the invention. Such ~-; 20 modified polyhydroxyl compounds are obtained when polyaddition ` reactions (e.g. reactions between polyisocyanates and amino-functional compounds) or polycondensation reactions (e.g. between formaldehyde and phenols and/or amines) are carried out in ~itu ~; in the above-mentioned hydroxyl compounds. Processes of this ~ind have been described, for example, in German Auslege~chriften ` 1,168,075 and 1, 260,142, and German Offenlegun~sschriften ` ~ 2,3~4,134: 2,423,984; 2~5l2~385s 2,513,815; 2,550,796; 2,550,797J
2,550,833 and 2,550,862. According to U. S. Patent 3,869,413 or German Offenlegungsschrift 2,550,860, modified polyhydroxyl LeA 17,796 -31-10~8523 compounds of this kind can also ~e obtained by mixing a previously prepared aqueous polymer dispersion with a poly-hydroxyl compound and then removing the water from the mixture.

When such modified polyhydroxyl compounds are used as starting components for the polyisocyanate polyaddition process, polyurethane resins with substantially improved mechanical properties are in many cases obtained.

The condensation reaction according to the invention is most advantageously carried out in a continuous cascade of stirrer vessels. In this variation of the process, the residual formaldehyde content can be accurately adjusted by varying the residence time in the individual vessels. The distribution of products in the reaction mixture and the average hydroxyl functionality of the mixture of polyhydric alcohols obtained from it by reduction can thus easily be varied within wide limits and with reproducible results.

The preparation according to the invention of a mixture of compounds containing hydroxyl groups can be carried out equally advantageously in a continuously operating reaction tube.
2Q To obtain the whole reaction volume at a desired pH, inorganic , or organic base is continuously added in the necessary quanti-ties at se~eral points along the tube. In this case, the distri-bution of products and hydroxyl functionality of the resulting polyhydric alcohols can be varied within wide limits by varying the rate of flow through the tube. With this variation of the ,...
process, it is, of course, also pos~ible to obtain mixture~
which contain predominantly higher molecular weight compounds and are free from colored by-products.

LeA 17,796 -32-1(1~8523 Mixtures containing predominant proportions of higher molecular weight products are also obtained when hydroxyaldehyde and hydroxyketone mixtures which contain predominantly low molecular weight components are subsequently after-treated with excess formaldehyde and in the presence of an inorganic or organic base at a pH of from 9 to 13, pre-ferably 10 to 11, for approximately 10 minutes to 12 hours at 10 to 100C, preferably 30 to 60C. By this method, not only are the low molecular weight compounds converted into higher molecular weight compounds by an alkaline catalyzed aldol reaction but in addition, a higher proportion of branched hydroxyaldehydes and hydroxyketones are obtained by additional methylolation on the carbon atom adjacent to the carbonyl group.
These branched hydroxyketones and hydroxyaldehydes have a considerably larger number of primary hydroxyl groups than the corresponding straight chained compounds. The reactivity of these mixtures with compounds which react with hydroxyl groups is thereby considerably increased. This is advantageous for some purposes; for example, when compounds prepared according to the invention are reacted with organic isocyanates, the presence of primary hydroxyl groups causes a much more rapid formation of urethanes than can be obtained with normàl, straight chain polyhydric alcohols containing secondary hydroxyl groups.

If desired, the hydroxyaldehydes and ~ydroxyketones ~ obtained by the process according to the invention can easily -~ be converted into polyhydric alcohol~ by reduction in known `~ manner: For example, the agueous solution obtained may be directly reduced with sodium borohydride at room temperature, LeA 17,796 -33-or it may be reduced electrolytically. Catalytic hydrogenation with hydrogen is another possible method. This may be carried out by any known methods for the reduction of sugars to sugar alcohols. Hydrogenation with Raney nickel in quantities of 5 to 20~ by weight, based on the ~uantity of hydroxyaldehyde and hydroxyketone mixture to be reduced, at hydrogen pres~ures of 50 to 200 kg/cm2 and temperatures of 20 to 200C i8 particularly suitable. Catalysts containing nickel, cobalt, copper, platinu~, rhodium or palladium on inert carriers may equally well be used.

As already described above, the process according to the invention can be controlled by suitable adjustment of the pH so that a high proportion of the hydroxyaldehydes and hydroxyketones formed are reduced in situ to polyhydric alcohols by the formaldehyde present in the reaction mixture. Alterna-1~ tively, the hydroxyaldehydes and ketones, which are formed in higher proportions by a slight deviation from the preferred pH
control, may subsequently be reduced with formaldehyde. In that case, excess formaldehyde and an inorganic base are added to the reaction solution and the solution is stirred at 10 to 100C, preferably at 30 to 60C, ~or a period of from 30 minutes to 12 hours while the pH is maintained at 9 to 13, preferably 10 to 11. In this way, it is possible not only to reduce the carbonyl function but at the same time, as already explained above, to synthesize higher molecular weight and branched chain products.
;~ 25 Sodium hydroxide, potassium hydroxide, calcium and barium hydroxide and so-called crown ether complexes of alkali metal atoms are preferred inorganic bases for accelerating the cros~ed Cannizzaro reaction.
:
The reduction reaction may be further accelerated by cocatalysts. The compounds used for this purpose are LeA 17,796 _34_ io~ss;~3 preferably oxalates of transition metals, in particular nickel, cobalt, iron, cadmium, zinc, chromium and manganese oxalate, and transition metals in the elementary form, e.g. nickel, cobalt, iron, copper, cadmium, zinc, chromium and manganese.
S It is particularly preferred to use activated nickel in the form of so-called Raney nickel and elementary zinc in the form of zinc powder.

Other suitable cocatalysts for the reduction with formaldehyde include amides of organic acids such as formamide, dimethylformamide and acetamide, and tetraalkyl ammonium salts, particularly tetramethylammonium chloride and tetraethylammonium chloride.

Summarizing, it is found that the process according to the invention affords the following important advantages over processes known in the art:

,,~

.

Le A 17 796 -35-10885~3 1. ~he process according to the invention gives ri~e to mix-tures of hydroxyaldehydes, hydroxyketones and polyhydric alcohols in which the proportion of polyhydric alcohols obtained by crossed Cannizzaro reaction, is from 30 to 75% by weight, a~ no unwanted decomposition product~ are formed. Hydrogenation or reduction of these mixture~ i~
particularly economical and simple since only relatively small quantities of carbonyl groups need to be converted into hydroxyl functions.

2. The process according to the invention give~ rise to mixtures of polyols, hydroxyaldehydes and hydroxyketones with differing hydroxyl functionalities, the proportions of which within the mixture can be varied as desired according to the intended use of the product. In par-;~ 15 ticular, the process may be used for preparing mixtures which contain over 80% by weight of compound-~ having more than four carbon atoms. The high reproducibility ~ of the distribution of products is an important advantage - over processes known in the art.

3. The process according to the invention gives rise to colorless products which can be hydrogenated without ~-~ further purification or used for the other purpoYesdescribed below. Purification of the product mixtuxe~
by distillation is not necessary.
4. The process according to the invention is particularly economical compared with processes known in the art.
The u~e of highly concentrated formaldehyde Qolutions represents an additional saving in energy cost which LeA 17,796 -36-1~85Z~

would otherwise be required for evaporation of the ~olvent.
Since virtually no unwanted side reactions occur in the process according to the invention, the products are obtained in yields of 95 to 98~, based on the quantity of formaldehyde put into the process.

Compared with the processes already known in the art, the process according to the invention proceed~ at a very high velocity and, therefore, makes it possible for extremely high volume/time yields to be obtained.
5. The lead catalysts preferably used in the process according to the invention can be used again, either immediately or after a simple treatment procesq, so that there is no ecologically harmful accumulation of lead waste.
6. The process according to the invention is distinguished by a particularly simple method of procedure, since the cocatalyst required need not be prepared pure in a separate step but can be produced in the mixing path or in situ, preferably already in the presence of the ~. _ catalyst.

The mixtures of hydroxyaldehydes and hydroxyketones obtainable according to the invention and the polyhydric alcohols produced from them by crossed Cannizzaro reac-tions or hydrogenation are valuable starting materials for numerous productæ which have interesting technical application~.

For example, the polyhydroxyl compounds obtained according to the invention are very suitable for use as chain lengthening agents or cro~q-linking agent~ for ''~
`~:
~ LeA 17,796 -37-1088~3 the production of polyurethane resin~ from polyisocyanates, low molecular weight polyhydroxyl compound~ and optionally higher molecular weight polyhydroxyl compounds, other chain lengthening agents, blowing agents, cataly~ts and other s known additives.

The polyi~ocyanates which may be used for this purpose include, for example, the aliphatic, cycloaliphatic, araliphatic, aromatic and heterocyclic polyisocyanates described by W. Siefken in Ju~tus Liebigs Annalen der Chemie, 562, pages 75 to 136.
These include: ethylene diisocyanate, tetramethylene-1,4-diisocyanate, hexamethylene-1,6-diisocyanate, dodecane-1,12-diisocyanate, cyclobutane-1,3-diisocyanate, cyclohexane-1,3- and 1,4-diisocyanate and any mixtures of these isomers, l-isocyanato-- 3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane as described in German Auslegeschrift 1,202,785 and U. S. Patent 3,401,190, hexahydrotolylene-2,4-diisocyana~e and -2,6-diisocyanate and ~;~ any mixture of these isomers, hexahydrophenylene-1,3-diisocyanate and/or 1,4-diisocyanate, perhydrodiphenylmethane-2,4'-diisocyanate `~ and/or 4,4'-diisocyanate, phenylene-1,3-diisocyanate and 1,4-: 20 diisocyanate, tolylene-2,4 - diisocyanate and tolylene-2,6-diisocyanate and any mixtures of these isomers, diphenylmethane-~- 2,4'-diisocyanate and/or 4,4'-diisocyanate, naphthylene-1,5-diisocyanate, triphenylmethane-4,4',4n-triisocyanate, polyphenyl-polymethylene polyisocyanates which can be obtained by aniline formaldehyde condensation followed by phosgenation and which : have been described, for example, in British Patents 874,430 and a48,671, m- and p-isocyanatophenyl-~ulphonyl lsocyanate~
; according to U. S. Patent 3,454,606, aryl polyi ocyanate~ such as those described, for example, in German Auslegeschrift LeA 17,796 -38-10~85;~3 1,157,601 and U. S. Patent 3,277,138, polyi~ocyanates having carbodiimide groups as described in German Patent 1,092,007 and U. S. Patent 3,152,162, diisocyanates of the kind described in U. S. Patent 3,492,330, polyisocyanates with allophanate groups as described, e.g. in British Patent 994,890, Belgian Patent 761,626 and published Dutch Patent Application 7,102,524, polyisocyanates with isocyanurate groupQ, e.g~ as described in U. S. Patent 3,001,973, in German Patents 1,002,789; 1,222,067 and 1,027,394 and in German Offenlegungsschriften 1,929,034 and 2,004,048, polyisocyanates with urethane groups as described, e.g. in Belgian Patent 752,261 or in U. S. Patent 3,394,164, polyisocyanates with acylated urea groups according to German Patent 1,230,778, polyisocyanates with biuret groups as described, e.g. in German Patent 1,101,394 (U. S. Patents 3,124,605 and 3,201,372) and in British Patent 889,050, poly-isocyanates prepared by telomerization reactions as described, for example, in U. S. Patent 3,6~4,106, polyi~ocyanates having ester groups such as those mentioned, for example, in Briti-Qh Patents 965,474 and 1,072,956, in U. S. Patent 3,567,763 and in German Patent 1,231,688, reaction products o~ the above-mentioned isocyanates with acetals according to German Patent 1,072,385 and polyisocyanates containing polymeric fatty acid groups according to U. S. Patent 3,455,883.

The distillation re~idues obtained from the commercial production of isocyanates and still containing isocyanate group~
-; may also be used, optionally as solutions in one or more of the ;~ above-mentioned polyisocyanates. Any mixture~ of the above-mentioned polyisocyanates may al~o be used.
. ,~
-~ In general, it is particularly preferred to use commercially readily available polyisocyanate~ such as tolylene-LeA 17,796 -39_ 10~85~3 2,4-diisocyanate and -2,6-diisocyanate and any mixtures of the~e isomers ("TDIn), polyphenyl-polymethylene polyi~ocyanates of the kind which can be prepared by aniline formaldehyde condensa-tion followed by phosgenation ("crude MDI n ) and polyisocyanate~
containing carbodiimide groups, urethane groups, allophanate groups,isocyanurate groups, urea groups or biuret group~
("modified polyisocyanates").

Suitable higher molecular weight polyhydroxyl com-pounds, especially those with a molecular weight from 800 to 10,000, preferably 1,000 to 6,000. These include, for example, polyesters, polyethers, polythioethers, polyacetals, poly-carbonates and polyester amides having at least 2, generally 2 to 8, preferably 2 to 4 hydroxyl groups, of the kind known ~ se for the production of both homogeneous and cellular polyurethanes.

Suitable polyesters with hydroxyl groups include, e.g.
reaction products of polyvalent, preferably divalent alcohols, to which trivalent alcohols may be added, and polyvalent, preferably divalent carboxylic acids. Instead of free poly-carboxylic acids, the corresponding polycarboxylic acid anhy-drides or corresponding polycarboxylic acid esters of lower alcohols or mixtu~es thereof may, of course, be used for pre-paring the polyesters. The polycarboxylic acids may be alipha-tic, cycloaliphatic, aromatic and/or heterocyclic and they may be substituted, e.g. by halogen atoms, and/or unQaturated.

The following are mentioned as examples: succinic , `~ ~ acid, adipic acid, ~uberic acid, azelaic acid, ~ebacic acid, ~LeA 17,796 -40-lO~S~3 phthalic acid, isophthalic acid, trimellitic acid, phthal~c acid anhydride, tetrahydrophthalic acid anhydride, hexahy-drophthalic acid anhydride, tetrachlorophthalic acid anhydride, endomethylene tetrahydrophthalic acid anhydride, glutaric acid anhydride, fumaric acid, dimeric and trimeric fatty acids ~uch as oleic acid, which may be mixed with monomeric fatty acids, dimethyl terephthalate and terephthalic acid-bis-glycol ester~.

The following are example~ of ~uitable polyvalent alcohols: Ethylene glycol, propylene glycol-(1,2) and -(1,3), butylene glycol-~1,4) and -(2,3), hexanediol-(1,6), octanediol-(1,8), neopentylglycol, cyclohexanedimethanol ~1,4-bis-hydroxy-methylcyclohexane), 2-methyl-1,3-propanediol, glycerol, trimethylolpropane, hexanetriol-(1,2,6), butanetriol-(1,2,4), trimethylolethane, pentaerythritol, quinitol, mannitol and sorbitol, methylglycoside, diethylene glycol, triethylene glycol, tetraethylene glycol, higher polyethylene glycols, dipropylene glycol, higher polypropylene glycols, dibutylene glycol and higher poly~utylene glycols. The polyesters may also contain a proportion of carboxyl end groups. Polyesters of lactones ~uch as ~-caprolactone or hydroxycarboxylic acids such as ~-hydroxy-caproic acid may also be used.

The polyethers which may be uRed according to the inven-tion which have at least 2, generally 2 to 8 and preferably 2 to ~, -~ 3 hydroxyl groups are also known per se. They are prepared for sA~ 25 example, by the polymerization of epoxides such as ethylene oxide, ~ propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide or ,~,, epichlorohydrin, either on its own, e.g. in the presence of boron trifluoride or by the addition of these epoxides, either as ~;~ mixtures or successively, to ~tarting components having reactive LeA 17,796 -41-10~

hydrogen atoms. Such starting compounds include alcohols or amines, e.g. water, ethylene glycol, propylene glycol-(1,3) or -(1,2), trimethylolpropane, 4,4'-dihydroxydiphenylpropane, aniline, ammonia, ethanolamine, or ethylene diamine. Sucrose polyethers may also be used according to the invention, e.g.
those described in German Auslegeschriften 1,176,3S8 and 1,064,938.
It is in many cases preferred to use polyethers which contain predominantly primary hydroxyl groups in particular up to 90%
by weight, based on all the hydroxyl groups present in tbe polyether. Polyethers modified with vinyl polymers, e.g. the compounds obtained by polymerization of styrene or acryloni-trile in the presence of polyethers (U. S. Patents 3,383,351;
3,304,273; 3,523,093 and 3,110,695 and German Patent 1,152,536) are also suitable, as well as polybutadienes which have hydroxyl groups.

Particularly to be mentioned among the polythioethers are the condensation products obtained by reacting thio-diglycol on its own and/or with other glycols, dicarboxylic acids, formaldehyde, aminocarboxylic acids or amino alcohol~.
The products obtained are polythio mixed etherQ, polythio ether esters or polythio ether ester amides, depending on ;~ the co-components.

~-~ Suitable polyacetals include, for example, the com-pounds which can be prepared from glycols such as diethylene glycol, triethylene glycol, 4,4'-dioxethoxy-diphenyl dimethylmethane, hexanediol and formaldehyde. Suitable . ,~
,;
, ~

LeA 17,796 -42-10~8S23 polyacetals for the purpose of the invention may also be prepared by the polymerization of cyclic acetals.

The polycarbonates with hydroxyl groups used may be of the kind known per se, for example those which can be prepared by the reaction of diols such as propanediol-(1,3), butanediol-(1,4) and/or hexanediol-~1,6), diethylene glycol, triethylene qlycol or tetraethylene glycol with diarylcarbonates, e.q. with diphenylcarbonate or phosgene.

~,~
~ ' ~

, ~:

} ~

~`~

LeA 17,796 -43-10~85Z3 Suitable polyester amides and polyamides include, for example, the predominantly linear condensates prepared from polyvalent saturated and unsaturated carboxylic acids or their anhydrides and polyvalent ~aturated and unsaturated s amino alcohols, diamines, polyamines and mixtures thereof.

Polyhydroxyl compounds already containing urethane or urea groups and modified or unmodified natural polyols such as castor oil or carbohydrates or starch may also be used. Addition products of alkylene oxides and phenol for-maldehyde resins or of alkylene oxides and urea formaldehyderesins are also suitable for the purpose of the invention.

Representatives of these compounds which may be used according to the invention have been described, for example, in High Polymers, Vol. XVI, "Polyurethanes, Chemistry and Technology" by Saunders-Frisch, Interscience Publishers, New York, London, Volume I, 1962, pages 32 - 42 and pages 44 - 54 and Volume II, 1964, pages 5 - 6 and 198 - 199 and in Xunststoff-Handbuch, Volume VII, Vieweg-Hochtlen, Carl-Hanser-Verlag, Munich, 1966, e.g. on pages 45 to 71.

Mixtures of the above mentioned compounds which contain at least two hydrogen atoms capable of reacting with isocyanates and have a molecular weight of from 800 to 10,000 may, of course, also be used, for example mixtures of polyethers and pQlyesters.
~ -::
~ ~25 The starting components which may be used according ~ 3` ~
to the invention may also include compounds with a molecular weight of from 32 to 400 which have at least two hydrogen atoms capable of reacting with isocyanates. These compounds LeA 17,796 -44-10~85;~3 are also understood to be compounds containing hydroxyl group~
and/or amino groups and/or thiol groups and/or carboxyl groups, preferably hydroxyl groups and/or amino groups. They serve as chain lengthening agents or cross-linking agents. ~hey generally have from 2 to 8 hydrogen atoms capable of reacting with isocyanates, preferably 2 or 3 such hydrogen atoms. ~he following are examples of such compounds:
Ethylene glycol, propylene glycol-(1,2) and -(1,3), butylene glycol-(1,4) and -(2,3), pentanediol-(1,5), hexanediol-(1,6), octanediol-(1,8), neopentyl glycol, 1,4-bis-hydroxymethyl-cyclohexane, 2-methyl-1,3-propanediol, glycerol, trimethylol propane, hexanetriol-(1,2,6), trimethylolethane, penta-erythritol, quinitol, mannitol and sorbitol, diethylene gly-col, tetraethylene glycol, higher polyethylene glycols with a molecular weight of up to 400, dipropylene glycol, higher polypropylene glycols with a molecular weight of up to 400, dibutylene glycol, higher polybutylene glycols with a molecu-lar weight of up to 400, 4,4'-dihydroxy-diphenyl propane, ~ dihydroxymethyl-hydroquinone, ethanolamine, diethanolamine, ~ 20 triethanolamine, 3-aminopropanol, ethylene diamine, 1,3-diaminopropane, l-mercapto-3-aminopropane, 4-hydroxyphthalic acid, 4-aminophthalic acid, succinic acid, adipic acid, hydrazine, N,N-dimethylhydrazine, 4,4'-diamino-diphenylmethane, tolylenediamine, methylene-bis-chloroaniline, methylene-b1s-ZS anthranilic acid ester, diaminobenzoic acid esters and theisomeric chlorophenylene diamines.
. ~
,. ~i ~ .
In this case again, there may be used mixtures of various compounds having a molecular weight of from 32 to 400 and containing at least two hydrogen atom~ capable of reacting with isocyanates.
LeA 17,796 _45_ ~OWS;~3 Polyhydroxyl compounds containing high molecular weight polyadducts or polycondensates in a finely dispersed or dissolved form may also be used according to the inven-tion. Such modified polyhydroxyl compounds are obtained S when polyaddition reactions (e.g. reactions between poly-isocyanates and aminofunctional compounds) or polycondensa-tion reactions (e.g. between formaldehyde and phenols and~or amines) are carried out ln situ in the above mentioned hydroxyl compounds. Processes of this kind have been described, for example, in German Auslegeschriften 1,168,075 and 1,260,142 and in German Offenlegungsschriften 2,324,134;
2,423,984; 2,512,385; 2,513,815: 2,550,796; 2,550,797;
2,550,833 and 2,550,862. These modified polyhydroxyl com-pounds may also be obtained according to U.S. Patent 3,869,413 or German Offenlegungsschrift 2,550,860 by mixing a previously prepared aqueous polymer dispersion with a polyhydroxyl compound and then removing the water from the mixture.

When modified polyhydroxyl compounds of the kind mentioned above are used as starting components for the polyisocyanate polyaddition process, polyurethane resins with substantially improved mechanical properties are in many cases obtained.

When the polyhydroxyl compounds obtained according . :- ~: 25 to the invention are reacted on their own (without the addition of other isocyanate reactive components) with strongly elasticizing polyisocyanates such as polyisocya-~: nates with a biuret structure (German Auslegeschrift 1,543,178), hard, lightfast, scratch resistance and solvent . LeA 17,796 -46-~0~85Z3 resistance coatings and lacquers are obtained.

Polyurethane foams prepared with the aid of the polyol mixtures obtainable according to the invention are distinguished by their exceptionally high fl~me re~istance.

Polyether alcohols having a high functionality can be obtained by propoxylation and/or ethoxylat~on of the polyols. At high hydroxyl numbers, these polyether alcQhols are suitable for the production of rigid or semirigid cellu-lar polyurethane resins and at low hydroxyl numbers they are suitable for use as starting materials for highly ela~tic polyurethane foams.

Highly cross-linked polyesters which can be added to alkyd resins to improve their hardness can be obtained ~; by reacting the mixtures prepared àccording to the inven-tion of polyhydric alcQhols with polybasic carbcxylic acids of the kind mentioned above, e.g. phthalic acid, i80phthalic acid, terephthalic acid,tetra-and hexahyarophthalic acid, adipic acid or maleic acid. The reactions inc~lude the usual processes of polycondensation, for example, as de-cribed in Houben-Weyl, Methoden der organischen Chemiè, Vol. XIV
12, page 40. The hydroxyl polyesters synthesized from the hydroxyl comFounds prepared according to the inventlon ar-, of course, also suitable for u~e as starting component~
for the production of polyurethane resin~.

25 ~ ~ ~h- polyhydr~c alcohol~ and hydroxy~ld~byde~ ~nd hydroxyketones pre~parèd according to the invention can al~o ~ol'b,: ' ~ , be readily reacted with long chain, aliphatic monocarboxyliG
acid~ such a~ caprylic, capric, lauric, myri-tic, palmitic, st-aric, ol-ia, linoleic, arachidonic or beh-nic acid and LeA i7,796 _~7_ 10t~85~3 derivatives thereof, e.g. their methyl or ethyl esters or their anhydrides or mixed anhydrides to produce hydroxyl-containing esters. These esters, like the ethoxylation products of the polyols or the carbamic acid esters obtained S as reaction products of the polyhydroxyl compounds according to the invention with long chain monoisocyanates such as n-octyl, n-decyl, n-dodecyl, myristyl, cetyl or stearyl isocyanates (see, for example, K. Lindner, Tenside Vol.
III, Wissenschaftliche Verlagsgesellschaft Stuttgart, 1964, page 2336) are non-ionogenic surface active compounds which may serve as valuable emulsifiers, wetting agents and plasticizers. The compounds according to the invention may also be used as moisturizers in cosmetics and plastics but they may also be used as other products, e.g. as anti-freezes.

They may also serve as carbohydrate-containing sub-strates in nutrien~ soils for microorganisms. Those products consisting mainly of hydroxyaldehydes and hydroxyketones containing five and six carbon atoms have been found to be particularly suitable for this purpose.

The following Examples serve to illustrate the process according to the invention. The figures given are -~ parts by weight or percentages by weight unless otherwise indicated.

.
:

LeA 17,796 -48-10885Z~
EXAMPLES

Example 1 500 parts of a 37% aqueous formalin solution ~6.7 mol of formaldehyde) and 5 part~ (0.013 mol) of lead acetate are heated together under reflux. In another vQ~sel~
5 parts (0.08 mol) of ethylene glycol are mixed with 8 part~
(0.08 mol) of 35% hydrogen peroxide and immediately there-after introduced into the boiling formalin solution which is thereby adjusted to pH 2.4. The heating bath is removed and a mixture of equal parts of potassium hydroxide and ~; water are added dropwise until the mixture starts to boil ~ again spontaneously at a pH of 8.5. The consumption of ,.- potassium hydroxide solution, calculated as Qolid pota~sium ~'' hydroxide, is 12.3 parts up to this stage~;fo,rmaldehyde conver~ion = 21.4%). Potassium hydroxide solution con-~; tinues to be added dropwise to maintain the exothermic reaction. The rate of addition is adjusted 80 tha~t the"pH
of the reaction mixture falls to 7~0. The r--idual formal-dehyde content of the solution has dropped to 0.3~ after 2~D~ 25 minutes;. ~Th-~t~otal Gonsum ~ ion of potassium hydroxido -~ - is 21.3 parts. 1.5 parts of sulphuric acid in 10 parts of water a~re~added to inactlvate the catalyst. Thi8 c~u~e~
precipitation of lead sulphate, and the pH drop- to 4 . 8.
,The~reaction mixture i left to cool, the precipitat~ i8 filtered~off~ànd ~,e ~olution l~ concentràted by oV pora-~` ~ tion in a~wa~ ~et Yacu~ 21a part:~ of a mix'c ~ of polyhydr~c alcohol-,~ hydroxyaldehydes and hydroxykotone9 containinq 10~ o~wator and having a vi8cosity iat 50C
of 1.16a Pa.s ~13.832 Pa.s ~t 25C) and conta~ning-53.6~
of reduced components (aalculated a9 glucoso) are obtalned .; ~ :
LeA 17,796 -49-10~85~3 Example 2 500 parts of a 37% aqueous formalin solution (6.17 mol of formaldehyde) and 5 parts (0.013 mol) of lead (II)-acetate are together heated to reflux. A mixture of 7.4 parts (0.08 mol) of glycerol and 8 parts (0.08 mol) of 35%
hydrogen peroxide is then added to thiQ solution. From that point, the method is identical to that of Example 1.

After a reaction time of 27 minutes, during which the pH is maintained at 6.7-7.3 (after a starting phase at pH 8.3), the reaction is stopped when the residual formalde-hyde content is 0.1~.

Consumption of potassium hydroxide: 20.7 par~ts.
220 parts of a mixture of polyhydric alcohols, hydroxy-aldehydes and hydroxyketones containing 10% of water and having a viscosity at 50C of 3.581 Pa.s and containing 58.8% of reduced components, calculated as glucose, are obtained.

~he following two Examples show that it is par-ticularly advantageous to carry out the oxidation of the polyhydric alcohol in the presence of a metal salt which is suitable for use as catalyst for the main reaction (in these Examples, lead(II)acetate), since the ene-diol com-pounds formed on oxidation appeax to be bound by complex formation so that further oxidation to dicarboxylic or polycarboxylic acid~ prevented.

Example 3 500 parts of a 37% aqueous formalin solution (6.17 mol of formaldehyde) are heated to reflux. In another vessel, LeA 17,796 _50_ 10~

5 parts ~0.013 mol) of lead(II)-acetate are mixed with S part~
(0.08 mol) of ethylene glycol and 8 part~ (0.08 mol) of 35%
hydrogen peroxide. This mixture i~ introduced into the boiling formalin solution. From that point, the procedure is the same as that of Example 1.

After a reaction time of 20 minutes, during which the pH i9 maintained at 6.8-7.3 after a starting phase at pH 8.4, the reaction is stopped when the re~idual formalde-hyde content is 0.3%. Consumption of potas~ium hydroxide:
15.2 parts.

212 parts of a mixture of polyhydric alcohols, hydroxyaldehydes and hydroxyketones containing 10% of water and having a visco~ity at 50C of 1.828 Pa.s and containing 51.6% of reducing constituents, calculated as gluco~e, are obtained.
:;
Example 4 SO~ parts of a 37% aqueous formalin solution (6.17 mol) are heated to reflux. A mixture of 5 parts (0.013 mol) of lead(II)-acetate, 7.4 parts (0.08 mol) of glycerol and 8 parts (0.08 mol) of 37% hydrogen peroxide is added as in Example 3. From that point, the procedure i9 the same ; as that of Example 1. After a reaction time of 2S minutes, during whioh the pH i~ maintained at 6.9-7.2 (after a tarting phase at pH 7.5), the reaction 19 stopped when the 2$ residual formaldehyde content i~ 1.2%. Con~ùmption o$
, ~ ~
potassium hydroxide: 14.6 parts.

; 210 parts of a mixture of polyhydric alcohol8, hydroxyaldehyde and hydroxyketone~ containing 10% of ~ater LeA 17,796 -51-~,' 10~

and having a viscosity at 50C of 1.47~ Pa.~ and containing 56.9% of reducing constituents, calculated as glucose, are obtained.

The following Examples show that a tetravalent lead compound such as lead tetraacetate or lead dioxide may al~o be used as oxidizing agent to oxidize the polyhydric alcohol. A lead(II) compound is thereby obtained, which together with the previously formed enediol compound, forms the reguired catalyst/co-catalyst system.

Example 5 500 parts of a 37S aqueous formalin solution (6.17 mol of formaldehyde) are heated to reflux. In another vessel, 8.9 parts (0.02 mol) of lead tetraacetate are mixed with 5 parts (0.08 mol) of ethylene glycol. The mixture obtained ~- 15 is added to the boiling formalin solution. The proceaure is otherwi~e the same as that of Example 1.

`~ After a reaction time of 22 minutes, during which , ~
the pH is maintained at 6.9 - 7.4 after a starting phase at ~ pH 8.5, the reaction is stopped at a residual formaldehyde -~ 20 content of 0.6%. Consumption of potassium hydroxide is 23.8 parts.

- 213 parts of a mixture of polyhydric alCohols, ~;~; hydroxy alde~ydes and hydroxy ketones contalning 10~ of ~- water and having a viscosity at 50C of 1.647 Pa.s and containing 54.2% of reduc~ng constituents, calculatea as glucose, are obtained.
LeA 17,796 -52-~08B5~

Example 6 500 parts of a 37~ aqueous formalin solution (6.17 mol of formaldehyde) are heated to reflux. In a second ves-sel, 10 parts (0.16 mol) of ethylene glycol are mixed with 5 parts (0.016 mol) of lead dioxide. The mixture obtained is added to the boiling formalin solution. The procedure is otherwise the same as that of Example 1.

After a reaction time of 28 minutes, during which the pH is maintained at 6.6 - 7.2, the reaction is stopped at a residual formaldehyde content of 0.1~. Consumption of potassium hydroxide is 21.4 parts.

219 parts of a mixture of polyhydric alcohol~, hydroxy alcohol~ and hydroxyketone~ containing 10% of water and having a vi~cosity at 50C of 793 mPa.-s~and containing 51.2% of reducing constituents/ calculated as glucose, are obtained. ~ ~-Example 7 A mixture of 20 parts of a polypropylene oxide having a hydroxyl number of ~50 started on ethylene diamine, 13 parts of a polypropylene oxide started on sugar/propylene glycol and having an average functionality of 3 and a hydroxy~1 number of 550, 4.8 partJ of the polyol mixture prepared accordlng to ; 25 ~xample 1, 3 parts of ~-¢aprolactam, 0.6 parts of a commercial polyether siloxane foam ~tabilizex (stabilizer OS 710 of aAYER AGI, LeA 17,796 -53-: , lOWS~

18 parts of trichlorofluoromethane and0.5 parts of dimethyl cyclohexylamine is mixed with 80 parts of a crude diphenyl methane diisocyanate (isocyanate content 31%) for 5 seconds with vigorous stirring S and then poured into a mold. The foam solidifies after 2 minutes and is hardened right through after a further 10 minutes. A highly flame-resistant foam having a gross density of 33.4 g/~ is obtained.

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Claims (10)

The embodiments of the invention in which an exclusive pro-perty or privilege is claimed are defined as follows:
1. A process for the preparation of mixtures of low molecular weight polyhydric alcohols and hydroxyaldehydes and-hydroxyketones by the condensation of formaldehyde by itself in the presence of from 0.01-10% by weight, based on the quantity of formaldehyde, of metal compounds as catalyst and from 0.1-10% by weight, based on the formaldehyde, of co-catalysts based on compounds which are capable of enediol formation, the improvement which comprises condensing aqueous formalin solutions and/or paraformaldehyde dispersions con-taining from 20-65% by weight of formaldehyde at a reaction temperature of from 70-120°C in the presence of (I) a soluble or insoluble compound of a metal of the 2nd -4th main or 1st to 8th sub-group of the Periodic System of Elements, optionally bound to a high molecular weight carrier, and (II) a co-catalyst prepared by partial oxidation of a divalent or higher valent alcohol containing at least 2 adjacent hydroxyl groups and having a molecular weight of between 62 and 242 or of a mixture of such alcohols, the pH of the reaction solution being maintained at between 6.0 and 9.0 by controlled addition of an inorganic and/or organic base up to a conversion rate of from 5 to 40% and thereafter at between 4.5 and 8.0 until termination of the condensation reaction to that during this second phase the pH is lower by 1.0 - 2.0 units than in the first phase of the reaction; and then stopping the reaction by inactiva-tion of the catalyst in known manner when the residual formaldehyde content is 0 - 10% by weight; removing catalyst;
and, optionally reducing the aldehyde and keto groups present in the reaction product to hydroxyl groups.
2. The process of Claim 1, wherein the catalysts used are ion-exchangers charged with metal ions.
3. The process of Claim 1, wherein the partial oxidation is conducted using an aqueous solution of an oxidizing agent from the group consisting of hydrogen peroxide, nitric acid, sodium hypochlorite, ammonium peroxy-disulfate, salts of heptavalent manganese or lead(IV) salts.
4. The process of Claim 1, wherein the divalent or higher valent alcohols having at least two hydroxyl groups adjacent to each other or mixtures of such alcohols are used in quantities of from 0.001 OH equivalents to 0.1 OH equivalents, based on 1 mol of formaldehyde, to prepare the co-catalyst.
5. The process of Claim 1, wherein the partial oxidation is conducted using an oxidizing agent in a quantity of at least 0.001 equivalents per mol of formaldehyde and not more than a quantity equivalent to the quantity of alcohol used in the process.
6. The process of Claim 1, wherein a lead(IV) compound is used both as the catalyst and as an oxidizing agent for the partial oxidation.
7. The process of Claim 1, wherein the hydroxy-aldehydes and hydroxyketones contained in the reaction products are subsequently reduced with formaldehyde by a crossed Cannizzaro reaction at a pH range of 9 - 13.
8. The process of Claim 1, wherein formaldehyde condensation is carried out continuously in a cascade of stirrer vessels.
9. The process of Claim 1, wherein the condensation of formaldehyde is carried out continuously in a reaction tube.
10. A process for the preparation of polyurethane resins comprising reacting a) polyisocyanates with b) low molecular weight polyhydric alcohols and hydroxyaldehydes and hydroxyketones produced by the condensation of formaldehyde by itself in the presence of from 0.01-10% by weight, based on the quantity of form-aldehyde, of metal compounds as catalyst and from 0.1-10% by weight, based on the formaldehyde, of co-catalysts based on compounds which are capable of enediol formation, the com-ponent b) being produced by condensing aqueous formalin solutions and/or paraformaldehyde dispersions containing from 20-65% by weight of formaldehyde at a reaction temperature of from 70-120°C in the presence of (I) a soluble or insoluble compound of a metal of the 2nd - 4th main or 1st to 8th sub-group of the Periodic System of Elements, optionally bound to a high molecular weight carrier, and (II) a co-catalyst prepared by partial oxidation of a divalent or higher valent alcohol containing at least 2 adjacent hydroxyl groups and having a molecular weight of between 62 and 242 or of a mixture of such alcohols, the pH of the reaction solution being maintained at between 6.0 and 9.0 by controlled addition of an inorganic and/or organic base up to a conversion rate of from 5 - 40% and thereafter at between 4.5 and 8.0 until termination of the condensation reaction so that during this second phase the pH is lower by 1.0 - 2.0 units than in the first phase of the reaction; and then stopping the reaction by inactivation of the catalyst in known manner when the residual formaldehyde content is 0-10% by weight; removing catalyst; and, optionally reducing the aldehyde and keto groups present in the reaction product to hydroxyl groups;
c) higher molecular weight polyhydroxyl compounds and/or other chain lengthening agents, optionally in the presence of d) blowing agents, catalysts and other known additives.
CA285,691A 1977-03-30 1977-08-29 Process for the preparation of low molecular weight polyhydroxyl compounds Expired CA1088523A (en)

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DE19772714084 DE2714084A1 (en) 1977-03-30 1977-03-30 Poly:ol, hydroxy-aldehyde and hydroxy-ketone cpds. prodn. - by catalytic condensation of formaldehyde in neutral to alkaline then more acid medium
DEP2714084.7 1977-03-30

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US4288566A (en) * 1979-02-22 1981-09-08 Bayer Aktiengesellschaft Process for the production of highly elastic foams containing urethane groups from polyethers, modified polyisocyanates and cross-linking agents
US4358619A (en) 1978-02-25 1982-11-09 Bayer Aktiengesellschaft Process for the production of low molecular weight polyhydroxyl compounds
US4654377A (en) * 1977-12-16 1987-03-31 Bayer Aktiengesellschaft Process for the preparation of low molecular weight polyhydroxyl compounds
US5162384A (en) * 1991-09-13 1992-11-10 Minnesota Mining And Manufacturing Company Making foamed plastic containing perfluorinated heterocyclic blowing agent
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US5897727A (en) * 1996-09-20 1999-04-27 Minnesota Mining And Manufacturing Company Method for assembling layers with a transfer process using a crosslinkable adhesive layer
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US4654377A (en) * 1977-12-16 1987-03-31 Bayer Aktiengesellschaft Process for the preparation of low molecular weight polyhydroxyl compounds
US4358619A (en) 1978-02-25 1982-11-09 Bayer Aktiengesellschaft Process for the production of low molecular weight polyhydroxyl compounds
US4288566A (en) * 1979-02-22 1981-09-08 Bayer Aktiengesellschaft Process for the production of highly elastic foams containing urethane groups from polyethers, modified polyisocyanates and cross-linking agents
US5162384A (en) * 1991-09-13 1992-11-10 Minnesota Mining And Manufacturing Company Making foamed plastic containing perfluorinated heterocyclic blowing agent
US5539008A (en) * 1993-12-29 1996-07-23 Minnesota Mining And Manufacturing Company Foamable composition containing unsaturated perfluorochemical blowing agent
US5631306A (en) * 1993-12-29 1997-05-20 Minnesota Mining And Manufacturing Company Foamable composition containing unsaturated perfluorochemical blowing agent
US7763578B2 (en) 2004-11-08 2010-07-27 3M Innovative Properties Company Preparation of polymeric foams using hydrofluoroether nucleating agents
WO2012158280A1 (en) 2011-05-19 2012-11-22 3M Innovative Properties Company Polymeric foams including fluorinated oxiranes, methods of preparation, and use of same
US9957428B2 (en) 2013-12-20 2018-05-01 3M Innovative Properties Company Fluorinated olefins as working fluids and methods of using same
US10280351B2 (en) 2013-12-20 2019-05-07 3M Innovative Properties Company Fluorinated olefins as working fluids and methods of using same
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