EP0000910A1 - Process for the preparation of low molecular polyhydroxy compounds - Google Patents

Abstract

Process for the preparation of low molecular weight polyhydroxyl compounds by self-condensation of formaldehyde hydrate in the presence of soluble or insoluble compounds of metals of the second to fourth main group or the second to eighth subgroup of the periodic system of the elements as a catalyst and optionally in the presence of compounds capable of endiol formation as a cocatalyst and / or of low molecular weight and / or higher molecular weight polyhydroxyl compounds, characterized in that the pH during the condensation reaction is controlled by the addition of 5 to 200 milliequivalents of a tertiary amine, based on 1 mol of formaldehyde.

Description

The present invention relates to an improved process for the production of formose by condensation of aqueous formaldehyde. The improvement consists in that, according to the invention, tertiary amines are used to control the pH instead of the previously used inorganic bases.

According to the invention, “formose” is understood to mean the mixtures of low molecular weight polyhydroxyl compounds (polyhydric alcohols, hydroxyaldehydes and hydroxyketones) which are known per se and which arise during the condensation of formaldehyde hydrate.

The preparation of mixtures of polyhydric alcohols, hydroxyaldehydes and hydroxyketones by self-condensation of the formaldehyde hydrate is described in numerous references. For example, Butlerow and Loew, Annalen 120, 295 (1861) and J.pr.Chem. 33.321 (1886), Pfeil, chemical reports 84, 229 (1951), Pfeil and Schroth, chemical reports 85, 303 (1952), RD _P artridge and AH Weias, Carbohydrate Research 24, 29-44 (1972), the formoses of glyceraldehyde or dioxyacetone according to Emil Fischer, the German patents 822 385, 830 951 and 884 794, the US patents 2 224 910, 2 269 935 and 2 272 378 and the English patent 513 Called 708. However, these known processes of the prior art have certain disadvantages (toxicologically unsafe catalysts, poor space-time yields, colored by-products); Recently, however, the applicant has developed new processes according to which practically colorless and free from disruptive by-products can be produced in high yield with common catalysts.

• Verbindungen mit 3 C-Atomen/Verbindungen mit 4 C-Atomen: O,5 bis 2,0
• Verbindungen mit 4 C-Atomen/Verbindungen mit 5 C-Atomen: 0,2 bis 2,0
• Verbindungen mit 5 C-Atomen/Verbindungen mit 6 C-Atomen: 0,5 bis 5,0
• wobei der Anteil der Komponenten mit 3 bis 6 C-Atomen mindestens 75 Gew.-%, vorzugsweise mehr als 85 Gew.-%, bezogen auf gesamten Co-Katalysator, beträgt.

One of these new processes consists in the condensation of the formaldehyde hydrate in the presence of soluble or insoluble lead (II) salts or lead (II) ions bound to high molecular weight carriers as a catalyst and a mixture of hydroxyaldehydes and hydroxyketones as co- Catalyst can run off, as it occurs in the condensation of formaldehyde hydrate and which is characterized by the following molar ratios:

• Compounds with 3 carbon atoms / compounds with 4 carbon atoms: 0.5 to 2.0
• Compounds with 4 carbon atoms / compounds with 5 carbon atoms: 0.2 to 2.0
• Compounds with 5 carbon atoms / compounds with 6 carbon atoms: 0.5 to 5.0
• wherein the proportion of components with 3 to 6 carbon atoms is at least 75% by weight, preferably more than 85% by weight, based on the total cocatalyst.

The reaction temperature is generally between 70 and 110 ° C, preferably between 80 and 100 ° C, and the pH of the reaction solution is brought to a value of 6.0-8.0, preferably 6.5-7.0, by controlled addition of a base up to a conversion of 10-60%, preferably 30-50%, and then set to a value of 4.0-6.0, preferably 5.0-6.0.

Surprisingly, the product distribution of the corresponding polyol, hydroxyaldehyde and hydroxyketone mixtures can be reproduced in a reproducible manner by this special pH control and by subsequent cooling at different levels of residual formaldehyde (0 to 10% by weight, preferably 0.5 to 6% by weight) Ways vary.

After the self-condensation of the formaldehyde hydrate has been interrupted by cooling and / or by deactivation of the lead-containing catalyst by means of acids, the catalyst is optionally removed in a manner known per se and the water contained in the products is evaporated. For more details, reference is made to the German patent application P 2 639 084.1.

A further possibility of producing highly concentrated colorless formoses in a high space-time yield consists in aqueous formalin solutions and / or paraformaldehyde dispersions in the presence of a soluble or insoluble metal catalyst and one by partial oxidation of a di- or polyvalent, having at least two adjacent hydroxyl groups To condense alcohol with a molecular weight between 62 and 242 or a mixture of such alcohols co-catalyst, the pH of the reaction solution being controlled by controlled addition of a base up to a conversion of 5 to 40% between 6.0 and 9, 0 holds and then until the condensation stops reaction to 4.5 to 8.0, so that it is now 1.0 to 2.0 units lower than in the first reaction phase, then the reaction with a residual content of 0-10 wt .-% formaldehyde by deactivating the Catalyst interrupts and the catalyst is removed. This procedure is described in detail in German patent application P 2 714 084.7.

High-quality formoses can also be produced by condensation of formaldehyde in the presence of a metal catalyst and more than 10% by weight, based on formaldehyde, of one or more dihydric or polyhydric low molecular weight alcohols and / or high molecular weight polyhydroxyl compounds. Such formose-polyol mixtures are the subject of German patent application P 2 714 104.4.

It is particularly economical to produce formose directly, ie without the detour via aqueous formalin solutions or paraformaldehyde, from synthesis gases containing formaldehyde. For this purpose, the synthesis gases, as are obtained in the industrial production of formaldehyde, are passed continuously or discontinuously at temperatures between 10 and 150 ° C. into an absorption liquid which consists of water, mono- or polyvalent low-molecular alcohols and / or higher-molecular polyhydroxyl compounds and / or compounds capable of endiol formation as cocatalyst and / or soluble or insoluble metal compounds, which may be bound to high molecular weight supports, exist as a catalyst and have a pH of 3 to 10, the formaldehyde condenses directly in situ in the absorption liquid (if appropriate also in one downstream reaction tube or a downstream stirred tank cascade), the self-condensation of the formaldehyde at a residual formaldehyde content in the reaction mixture of 0 to 10% by weight stops by cooling and / or by deactivating the catalyst by means of acids and finally removes the catalyst. With regard to further details of this method, reference is made to the German patent application P 2 721 093.1.

The formoses prepared in this way can subsequently be converted into their hemiacetals by excess formaldehyde or can be α-methylolated by reaction with formaldehyde in the presence of bases.

Depending on how the formaldehyde condensation is carried out, the properties of the formose can be varied within wide limits. In general, the average molecular weight and thus the hydroxyl functionality of the formoses is higher the further the condensation reaction is carried out, i.e. the less residual formaldehyde is led to a residual formaldehyde content of 0 to 1.5% by weight when the condensation reaction is terminated, a formose is obtained which contains about 25% by weight of 5-carbon atoms and 45% by weight Contains compounds with 6 carbon atoms and about 20 wt .-% of compounds with 7 and more carbon atoms. In contrast, only about 10% of polyols, hydroxyketones and hydroxyaldehydes with 2.3 and 4 carbon atoms are obtained. This corresponds to an average hydroxyl functionality of approx. 5.

As explained above, other component distributions of the starter mixtures are obtained by stopping the formaldehyde self-condensation at somewhat higher residual formaldehyde. If the condensation reaction is terminated at a formaldehyde content of 2 to 2.5%, a mixture of polyhydric alcohols, hydroxyaldehydes and hydroxyketones with an average hydroxyl functionality of approx. 4 is obtained cancels that are even higher than 2.5.

In all of these processes, in addition to the self-condensation of the formaldehyde hydrate, crossed Cannizzaro reactions between formaldehyde and the carbonyl groups of the formaldehyde condensation products also occur to a relatively high degree, which means that the formoses thus obtained contain a significant amount of polyhydric alcohols in addition to hydroxyaldehydes and hydroxyketones . This can be advantageous for many purposes, especially when the intention is anyway to hydrogenate the formose to mixtures of polyhydric alcohols. For other applications (e.g. the production of special flame-retardant polyurethane foams or the use of formose as a substrate in the nutrient media of microorganisms), it would be advantageous if the formose had as high a proportion of reducing sugars as possible (i.e. as little as possible of the polyvalent forms created by a crossed Cannizzaro reaction) Alcohols) contains. In addition, the organic acids (essentially ants) that arise during the crossed Cannizzaro reaction are disruptive in many applications acid, also traces of acetic acid, lactic acid, glycolic acid and sugar acids), which can only be removed from the reaction mixture in a technically relatively complex process step using anion exchangers.

Surprisingly, it has now been found that the crossed Cannizzaro reaction during the formation of formose is largely suppressed if tertiary amines are used instead of the inorganic bases (generally alkali metal or alkaline earth metal hydroxides) used to set the desired pH. In contrast to the inorganic bases, such tertiary amines can, if desired, be easily removed from the reaction mixture by distillation; if appropriate, they can also remain in the formose and then act, for example, when the formose is used further as a starting component for the production of polyurethane plastics as catalysts for the polyisocyanate-polyaddition reaction. As was further found, surprisingly, the pH control during formaldehyde condensation when using tertiary amines as the base is largely uncritical: the pH during formation of the formose can fluctuate within relatively wide limits; it is generally between 4.5 and 9, preferably between 5 and 7.

The present invention thus relates to a process for the preparation of low molecular weight polyhydroxyl compounds by self-condensation of formaldehyde hydrate in the presence of soluble or insoluble compounds of metals of the second to fourth main group or the second to eighth subgroup of the periodic system the elements as a catalyst and, if appropriate, in the presence of compounds capable of forming endiols as cocatalyst and / or of low molecular weight and / or higher molecular weight polyhydroxyl compounds, which is characterized in that the pH during the condensation reaction by the addition of 5 to 200 milliequivalents, preferably 10 to 70 milliequivalents of a tertiary amine, based on 1 mol of formaldehyde, is controlled.

Surprisingly, the effect of the invention of largely suppressing the crossed Cannizzaro reaction only occurs when using teritarian amines, while primary or secondary amines behave similarly to inorganic bases, i.e. give rise to a noticeable crossed Cannizzaro reaction (see the comparative experiments in the example section ).

According to the invention, preference is given to those tertiary amines which contain an electron-attracting heteroatom in the β position to the tertiary nitrogen atom, for example a further tertiary nitrogen atom, a thioether group or particularly preferably an ether group. Examples of tertiary amines to be used according to the invention are trialkylamines such as triethylamine, tri-n-propylamine, tri-n-butylamine, N, N-dialkylbenzylamines with 1 to 5, preferably 1 or 2, carbon atoms in the alkyl groups, N-alkylpiperidines, N, N'-dialkylpiperazines and N-alkylmorpholines each having 1 to 5, preferably 1 or 2, carbon atoms in the alkyl groups, N-phenylmorpholine, N-benzylmorpholine, 1,2-bis-morpholylethane and addition products of ethylene oxide and / or propylene oxide on morpholine or piperazine with a molecular weight of up to about 2000, preferably up to about

1000. These last-mentioned compounds — like other basic polyethers known per se for polyurethane production (alkoxylation products of ammonia, primary and secondary mono- or polyamines) are of particular interest according to the invention because they can remain in the formose and later in use formose which can be incorporated as a starting component for the production of polyurethane plastics are catalysts for the polyisocyanate polyaddition reaction.

The self-condensation of the formaldehyde hydrate with the formation of hydroxyaldehydes and hydroxyketones is catalyzed according to the invention by insoluble, but preferably water-soluble compounds (in particular salts) of metals of the second to fourth main group or the second to eighth subgroup of the periodic system of the elements. Of particular technical interest as catalysts are also ion exchangers loaded with ions of these metals. In general, according to the invention, about 0.01 to 10% by weight, preferably 0.05 to 5% by weight, particularly preferably 0.1 to 1% by weight, based on the formaldehyde used, of the catalyst is also used. The use of strongly basic oxides or hydroxides of these metals (in particular of alkaline earth metal hydroxides) is less preferred according to the invention, since it favors the crossed Cannizzaro reaction again. If metal hydroxides are to be used as the catalyst, it is therefore advisable to use the smallest possible amounts of the catalyst, ie to work at the lower limit of the above range. Formates, acetates, phenolates, thiophenolates, salicylates, carbonates and nitrates are preferred according to the invention the metals or the ion exchangers already loaded with metal ions are used as catalysts. According to the invention particularly preferred catalysts are compounds of divalent _Ble i _s, in particular lead acetate.

According to the invention, the self-condensation of the formaldehyde hydrate is preferably allowed to proceed in the presence of compounds capable of forming endiols as cocatalysts. In general, 0.1 to 50, preferably 1 to 20, particularly preferably 5 to 15,% by weight, based on formaldehyde, of compounds capable of forming endiol are used. In principle, any compounds which contain a hydroxyl group to a carbonyl group are suitable for this purpose; However, co-catalysts preferred according to the invention are formose itself and oxidation products of polyhydric alcohols (in this connection see the literature cited at the beginning).

Instead of or in addition to these compounds capable of forming endiol, polyhydroxyl compounds can also be used in an amount of up to 200% by weight, preferably 10 to 100% by weight, based on the formaldehyde used. In this context, the polyhydroxyl compounds described in German patent application P 2 714 104.4 or the polyols mentioned below as starting components in the production of polyurethane plastics come into consideration.

As already mentioned, the procedure for the condensation of formaldehyde hydrate according to the invention in the presence of tertiary amines is largely uncritical. in the In general, temperatures from 10 to 150 ° C., preferably 70 to 110 ° C., particularly preferably 80 to 100 ° C., and in a pH range of preferably 4.5 to 9, particularly preferably 5 to 7, are used. In general, 10 to 70% by weight, preferably 20 to 65% by weight, particularly preferably 30 to 50% by weight, of formaldehyde-containing aqueous and / or alcoholic formalin solutions and / or paraformaldehyde dispersions are used according to the invention. The amount of the tertiary amine to be added according to the invention depends on the acid content of these starting components. However, it is generally between 5 and 200, preferably between 10 and 70, milliequivalents of tertiary nitrogen atoms per mole of formaldehyde. According to the invention, the total amount of the organic base can be added right at the start of the condensation reaction, since very little acid is formed as a result of the extensive suppression of crossed Cannizzaro reactions during the formation of formose, so that the pH decreases only very slowly during the condensation reaction. In the case of longer reaction times (if as complete a conversion of the formaldehyde as possible is desired), crossed Cannizzaro reactions occur to a small extent, so that it is then expedient to add the organic base in portions or continuously. The manner in which the tertiary amine is added also makes it possible to influence the reaction rate in the desired manner.

Of course, the method according to the invention can also be carried out continuously, for example in a stirred tank cascade. By varying the residence time and the pH value in the individual stirred tanks, in this process variant, set the residual formaldehyde content exactly. The product distribution in the formose obtained in this way can easily be varied and reproduced within wide limits. In a similarly favorable manner, the production of formose by the process according to the invention can also be carried out in a continuously operated reaction tube, in which the organic base can be added continuously in one or more places in the tube in order to maintain the desired pH in the entire reaction volume . In this case too, it is possible to vary the product distribution of the formose within wide limits by varying the flow times and the pH control.

The formoses obtained according to the invention are valuable starting materials for a large number of products which are of interest in terms of application technology; in particular, they are suitable as a polyol component in the production of polyurethane plastics.

• A) Polyisocyanaten mit
• B) niedermolekularen Polyhydroxylverbindungen sowie gegebenenfalls
• C) höhermolekularen Polyhydroxylverbindungen, weiteren Kettenverlängerungsmitteln, Treibmitteln, Katalysatoren und weiteren an sich bekannten Zusatzstoffen, welches dadurch gekennzeichnet ist, daß als Komponente B die erfindungsgemäß erhaltenen Formosen eingesetzt werden.

The invention thus also relates to a process for the production of optionally cellular polyurethane plastics by reacting

• A) with polyisocyanates
• B) low molecular weight polyhydroxyl compounds and optionally
• C) higher molecular weight polyhydroxyl compounds, further chain extenders, blowing agents, catalysts and other additives known per se, which is characterized in that the formoses obtained according to the invention are used as component B.

Suitable polyisocyanates in this context are, for example, the aliphatic, cycloaliphatic, araliphatic, aromatic and heterocyclic polyisocyanates, as described, for example, by W. Siefken in Justus Liebigs Annalen der Chemie, 562, pages 75 to 136, for example ethylene diisocyanate , 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,12-dodecane diisocyanate, cyclobutane-1,3-diisocyanate, cyclohexane-1,3- and -1,4-diisocyanate and any mixtures of these isomers, 1-isocyanate nato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (DAS 1 202 785, American patent specification 3 401 190), 2,4- and 2,6-hexahydrotoluenediisocyanate and any mixtures of these isomers, hexahydro-1,3- and / or -1,4-phenylene diisocyanate, perhydro-2,4'- and / or -4,4'-diphenylmethane diisocyanate, 1,3- and 1,4-phenylene diisocyanate, 2,4- and 2, 6-tolylene diisocyanate and any mixtures of these isomers, diphenylmethane-2,4'- and / or -4,4'-diisocyanate, naphthylene-1,5-diiso cyanate, triphenylmethane-4,4'-4 "- triisocyanate, polyphenyl-polymethylene-polyisocyanates as obtained by aniline-formaldehyde condensation and subsequent phosgenation and described, for example, in British Patents 874,430 and 848,671, m- and p Isocyanatophenylsulfonyl isocyanates according to the American patent specification 3 454 606, perchlorinated aryl polyisocyanates, as are described, for example, in German patent specification 1 157 601 (American patent specification 3 277 138), polyisocyanates containing carbodiimide groups, as described in German Patent 1,092,007 (American Patent 3,152,162), diisocyanates as described in American Patent 3,492,330, polyisocyanates containing allophanate groups, as described, for example, in British Patent 994,890, the Belgian patent 761 626 and the published Dutch patent application 7 102 524, polyisocyanates containing isocyanurate groups, as described, for example, in US Pat. No. 3,001,973, in German Patents 1,022,789, 1,222,067 and 1,027,394 and in German Offenlegungsschriften 1,929 034 and 2 004 048, polyisocyanates containing urethane groups, as described, for example, in Belgian patent specification 752 261 or in American patent specification 3 394 164, polyisocyanates containing acylated urea groups according to German patent specification 1 230 778, polyisocyanates containing biuret groups, such as these eg in d he German patent specification 1 101 394 (American patent specifications 3 124 605 and 3 201 372) and in British patent specification 889 050 are described, polyisocyanates prepared by telomerization reactions, as are described, for example, in American patent specification 3 654 106, polyisocyanates containing ester groups, such as they are mentioned, for example, in the British patents 965 474 and 1 072 956, in the American patent specification 3 567 763 and in the German patent specification 1 231 688, reaction products of the above-mentioned isocyanates with acetals according to the German patent specification 1 072 385 and polyisocyanates containing polymeric fatty acid residues U.S. Patent 3,455,883.

It is also possible to use the distillation residues obtained in the industrial production of isocyanate and containing isocyanate groups, optionally dissolved in one or more of the aforementioned polyisocyanates. It is also possible to use any mixtures of the aforementioned polyisocyanates.

The technically easily accessible polyisocyanates, e.g. 2,4- and 2,6-tolylene diisocyanate as well as any mixtures of these isomers ("TDI"), polyphenyl-polymethylene polyisocyanates, such as those produced by aniline-formaldehyde condensation and subsequent phosgenation ("crude MDI") and carbodiimide groups, Polyisocyanates containing urethane groups, allophanate groups, isocyanurate groups, urea groups or biuret groups ("modified polyisocyanates").

Suitable higher molecular weight polyhydroxyl compounds, especially those with a molecular weight of 800 to 10,000, preferably 1000 to 6000, are e.g. at least two, usually 2 to 8, but preferably 2 to 4, hydroxyl-containing polyesters, polyethers, polythioethers, polyacetals, polycarbonates and polyesteramides, as are known per se for the production of homogeneous and cellular polyurethanes.

The hydroxyl group-containing polyesters are e.g. Reaction products of polyhydric, preferably dihydric and optionally additionally trihydric alcohols with polyhydric, preferably dihydric, carboxylic acids. Instead of the free polycarboxylic acids, the corresponding polycarboxylic anhydrides or corresponding polycarboxylic esters of lower alcohols or mixtures thereof can also be used to produce the polyesters. The polycarboxylic acids can be aliphatic, cycloaliphatic, aromatic and / or heterocyclic in nature and optionally, e.g. by halogen atoms, substituted and / or unsaturated.

Examples of these include: succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, trimellitic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrachlorophthalic acid, fumaric acid, malefic acid, malefic acid, malefic acid, malefic acid, trimethylsulfonic acid, malefic acid, fatty acid, maleic acid, malefic acid, malefic acid, malefic acid, fumaric acid, anhydrous acid, malefic acid, fatty acid, maleic anhydride, maleic anhydride, maleic anhydride, maleic acid, fatty acid, maleic anhydride, maleic anhydride, maleic acid, fatty acid, maleic anhydride, malefic acid, fatty acid, maleic anhydride, maleic acid, fatty acid, maleic anhydride, maleic anhydride, maleic acid, fatty acid, maleic anhydride, maleic acid, fatty acid, maleic anhydride, maleic acid, fatty acid, maleic anhydride, maleic acid, fatty acid, such as, with monomeric fatty acids, dimethyl terephthalate and bis-glycol terephthalate. As polyhydric alcohols are e.g. 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-hydroxymethylcyclohexane), 2-methyl-1,3-propanediol, glycerin, trimethylolpropane, hexanetriol- (1,2,6), butanetriol- (1,2,4), trimethylolethane, pentaerythritol , Quinite, mannitol and sorbitol, methylglycoside, also diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycols, dipropylene glycol, polypropylene glycols, dibutylene glycol and polybutylene glycol in question. The polyesters can have a proportion of terminal carboxyl groups. Lactone polyester, e.g. ε-caprolactone or hydroxycarboxylic acids, e.g. ω-hydroxycaproic acid can be used.

The polyethers which come into question according to the invention, at least two, in the Rsgsl six to eight, preferably two to three, hydroxyl groups are those of the type known per se and are, for example, by poly merization of epoxides such as xylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide or epichlorohydrin with themselves, for example in the presence of BF ₃ , or by addition of these epoxides, optionally in a mixture or in succession, to starting components with reactive hydrogen atoms such as water, alcohols, ammonia or Amines, for example ethylene glycol, propylene glycol (1,3) odes - (1,2), trimethylolpropane, 4,4'-dihydroxy-diphenylpropane, aniline, ethanolamine or ethylenediamine. Sucrose polyethers, such as are described, for example, in German publications 1 176 358 and 1 064 938, are also suitable according to the invention. In many cases, such polyethers are preferred which predominantly (up to 90% by weight, based on all OH groups present in the polyether) have primary OH groups. Polyethers modified by vinyl polymers, such as those formed, for example, by polymerizing styrene and acrylonitrile in the presence of polyethers (American patents 3,383,351, 3,304,273, 3,523,093, 3,110,695, German patent 1,152,536), are also suitable Polybutadienes containing O _H groups.

Among the polythioethers, the condensation products of thiodiglycol with itself and / or with other glycols, dicarboxylic acids, formaldehyde, aminocarboxylic acids or amino alcohols should be mentioned in particular. _Depending on the co-components, the products are polythio ether, polythio ether ester or polythio ether ester amide.

As polyacetals e.g. the compounds which can be prepared from glycols, such as diethylene glycol, triethylene glycol, 4,4'-dioxethoxydiphenyldimethylmethane, hexanediol and formaldehyde, are suitable. Polyacetals suitable according to the invention can also be prepared by polymerizing cyclic acetals.

Suitable polycarbonates containing hydroxyl groups are those of the type known per se, which e.g. by reacting diols such as propanediol (1,3), butanediol (1,4) and / or hexanediol (1,6), diethylene glycol, triethylene glycol or tetraethylene glycol with diaryl carbonates, e.g. Diphenyl carbonate, or phosgene can be produced.

The polyester amides and polyamides include e.g. the predominantly linear condensates obtained from polyvalent saturated and unsaturated carboxylic acids or their anhydrides and polyvalent saturated and unsaturated amino alcohols, diamines, polyamines and their mixtures.

Polyhydroxyl compounds already containing urethane or urea groups and optionally modified natural polyols such as castor oil, carbohydrates or starch can also be used. Addition products of alkylene oxides on phenol-pormaldehyde resins or also on urea-formaldehyde resins can also be used according to the invention.

Representatives of these compounds that may be used according to the invention are e.g. in High Polymers, Vol. XVI, "Polyurethanes, Chemistry and Technology", written 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, as well as in the plastics manual, volume VII, Vieweg-Höchtlen, Carl-Hanser-Verlag, Munich, 1966, e.g. on pages 45-71.

Of course, mixtures of the above-mentioned compounds with at least two isocyanate-reactive hydrogen atoms with a molecular weight of 800-10,000, e.g. Mixtures of polyethers and polyesters can be used.

Compounds with at least two isocyanate-reactive hydrogen atoms with a molecular weight of 32-400 can also be used as starting components which may be used according to the invention. In this case too, this means hydroxyl groups and / or amino groups and / or thiol groups and / or carboxyl groups, preferably compounds having hydroxyl groups and / or amino groups, which serve as chain extenders or crosslinking agents. These compounds generally have 2 to 8 isocyanate-reactive hydrogen atoms, preferably 2 or 3 reactive hydrogen atoms.

Examples of such compounds are: ethylene glycol, (1,2) and - (1,3) propylene glycol, (1,4) and - (2,3) butylene glycol, (1,5) pentanediol, hexanediol (1,6), octanediol- (1,8), neopentyl glycol, 1,4-bishydroxymethyl-cyclohexane, 2-methyl-1,3-propanediol, glycerin, trimethylol propane, hexanetriol- (1,2,6), trimethylolethane, Pentaerythritol, quinite, mannitol and sorbitol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycols with a molecular weight of up to 400, dipropylene glycol, polypropylene glycols with a molecular weight of up to 400, dibutylene glycol, polybutylene glycols with a molecular weight of up to 400, 4,4'-propyl-dihydroxy, hydroquinone, ethanolamine, diethanolamine, triethanolamine, 3-aminopropanol, ethylenediamine, 1,3-diaminopropane, 1-mercapto-3-amino-propane, 4-hydroxy- or amino-phthalic acid, succinic acid, adipic acid, hydrazine, N, N ' -Dimethylhydrazine, 4,4'-diaminodiphenylmethane, toluenediamine, methylene-bis-chloroaniline, methylene-bis-anthrani oleic acid ester diaminobenzoic acid ester and the isomeric chlorophenylene diamines.

In this case too, mixtures of different compounds with at least two isocyanate-reactive hydrogen atoms with a molecular weight of 32-400 can be used.

According to the invention, however, polyhydroxyl compounds can also be used in which high molecular weight polyadducts or polycondensates are contained in finely dispersed or dissolved form. Such modified polyhydroxyl compounds are obtained if 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 directly in situ in the above-mentioned compounds containing hydroxyl groups. Such methods are described, for example, in German Auslegeschrift 1 168 075 and 1 260 142, and 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. However, it is also possible to mix a finished aqueous polymer dispersion with a polyhydroxyl compound in accordance with US Pat. No. 3,869,413 or German Offenlegungsschrift 2,550,860 and then remove the water from the mixture.

When using modified polyhydroxyl compounds of the type mentioned above as the starting component in the polyisocyanate polyaddition process, polyurethane plastics with significantly improved mechanical properties are produced in many cases.

The exclusive implementation of the polyhydroxyl compounds accessible according to the invention (without the use of other components which are reactive toward isocyanates) with strongly elasticizing polyisocyanates, such as e.g. Polyisocyanates with a biuret structure (DAS 1 543 178) result in hard, lightfast, scratch and solvent resistant coatings and varnishes.

By propoxylation and / or oxyethylation of the formose it is also possible to obtain high functionality polyether alcohols which are used in high OH number ranges for the production of hard or semi-hard cellular polyurethane plastics and at low OH numbers as starting materials for highly elastic polyurethane foams.

By reacting the formose produced according to the invention with polyvalent carboxylic acids of the above-mentioned type, e.g. Phthalic acid, isophthalic acid, terephthalic acid, tetra- and hexahydrophthalic acid, adipic acid or maleic acid by the usual methods of polyester condensation, as described for example in Houben-Weyl, Methods of Organic Chemistry, Vol. XIV 12, p. 40, can be branched polyesters synthesize that improve their hardness as additives to alkyd resins. The hydroxyl group-containing polyesters which are synthesized from the hydroxyl compounds prepared according to the invention can of course also be used as a starting component for the production of polyurethane plastics.

The phonoses produced according to the invention can also be very easily mixed with long-chain, aliphatic monocarboxylic acids, such as caprylic, capric, lauric, myristic, palmitic, stearic, oleic, linoleic, arachidonic or behenic acid, and their derivatives, such as convert the methyl or ethyl esters or the anhydrides or mixed anhydrides to hydroxyl-containing esters. Just like oxyethylation products of the polyols or reaction products of the polyhydroxyl compounds accessible according to the invention with long-chain monoisocyanates, such as n-octyl, n-decyl, n-dodecyl, myristyl, cetyl or stearyl isocyanate, these give carbamic acid esters (see, for example, K. Lindner, III, Wissenschaftliche Verlagsgesellschaft Stuttgart, 1964, p. 2336) are non-ionic, surface-active compounds which can be used as valuable emulsifiers, wetting agents or plasticizers. The formoses according to the invention can also be used as moisturizers in cosmetics and plastics. However, you can e.g. also serve as antifreeze.

They can also be used as a carbohydrate-containing substrate in microorganisms. Process products which consist mainly of hydroxyaldehydes and hydroxyketones containing 5 and 6 carbon atoms have proven particularly useful.

The following examples illustrate the process according to the invention. Unless otherwise noted, numerical values are to be understood as parts by weight or percentages by weight.

example 1

1000 g (12.3 mol of formaldehyde) of a 37% aqueous formalin solution are heated to reflux temperature together with 10 g (0.27 mol) of lead (II) acetate and 50 g of the formose described below as cocatalyst. The heating bath is then removed and dimethylbenzylamine is slowly metered in, so that the mixture continues to boil on its own. After 55 minutes, the residual formaldehyde content fell to 0.3%. The reaction is stopped by cooling.

Consumption of dimethylbenzylamine: 20 g.

After concentrating in a water jet vacuum, 425 g of a 2.4% water-containing mixture of polyhydric alcohols, hydroxy aldehydes and hydroxy ketones with a content of reducing portions, calculated as glucose, of 71.2%, a viscosity at 50 ⁰ C of 1810 mPa.s and an OH number of 760. This mixture can be hydrogenated according to known procedures with Raney nickel as a catalyst. A mixture of polyhydric alcohols with a water content of 3.8% and a viscosity at 50 ° C of 616 mPa.s.

• 3000 Teile einer 37 %igen wäßrigen Formaldehydlösung (37 Mole Formaldehyd) werden auf 70 -90°C erhitzt. Bei dieser Temperatur werden 30 Teile (0,08 Mol) Blei(II)-acetat zugegeben. Die Mischung wird dann weiter auf 100°C erhitzt und bei dieser Temperatur durch Zutropfen einer 15 %igen Ca(OH)₂-Suspension auf einen pH-Wert von 6,7 eingestellt.

Production of the co-catalyst:

• 3000 parts of a 37% aqueous formaldehyde solution (37 moles of formaldehyde) are heated to 70-90 ° C. At this temperature, 30 parts (0.08 mol) of lead (II) acetate are added. The mixture is then further heated to 100 ° C. and adjusted to a pH of 6.7 at this temperature by dropwise addition of a 15% strength Ca (OH) ₂ suspension.

After 6 hours the formaldehyde content has dropped to a value of 20% and the Ca (OH) ₂ supply is stopped. The pH of the reaction mixture now slowly drops. After a pH of 5.7 has been reached, the mixture is kept at this value by adding further Ca (OH) ₂ suspension. After a further 7.5 hours, a residual formaldehyde content of 0.5% is reached and the reaction mixture is cooled. An approximately 37% solution of a cocatalyst mixture consisting of hydroxyaldehydes and hydroxyketones is obtained, in which the molar ratio of the compounds with 3 C atoms and the compounds with 4 C atoms = 0.75, the molar ratio of the compounds with 4 carbon atoms and the compounds with 5 carbon atoms is 0.23 and the molar ratio of the compounds with 5 carbon atoms and the compounds with 6 carbon atoms is 0.67.

Example 2

1000 g (12.3 mole of formaldehyde) of a 37% aqueous solution of _F orma- linlösung be acetate together with 10 g (0.27 mol) of lead (II) and 50 g of the co-catalyst from Example 1 was heated to reflux. Then the heating bath is removed and methylpiperidine is slowly added so that the mixture continues to boil on its own. After 50 minutes, the residual formaldehyde content has dropped to 1.5. The reaction is stopped by cooling.

Consumption of methylpiperidine: 20 g.

After concentration in a water jet vacuum, 321 g of a mixture of polyhydric alcohols containing 3.3% water are obtained,

Hydroxyaldehydes and hydroxyketones with a content of reducing components, calculated as glucose, of 70.2%, a viscosity at 50 ^* C of 24 244 mPa.s and an OH number of 846.

Example 3

1000 g (12.3 mol of formaldehyde) of a 37% aqueous formalin solution are heated together with 10 g (0.27 mol) of lead (II) acetate and 50 g of the co-catalyst from Example 1 to the reflux temperature. Then the heating bath is removed and methylmorpholine is slowly added, so that the mixture continues to boil on its own. Formaldehyde is no longer detectable after 20 minutes. You cool down.

Consumption of methylmorpholine: 26 g.

After concentration in a water jet vacuum, 373 g of a 1.8% water-containing mixture of polyhydric alcohols, hydroxyaldehydes and hydroxyketones with a content of reducing components, calculated as glucose, of 80.4% and a viscosity at 50 ° C. of 58 190 mPa. s and an OH number of 898.

Example 4 (comparison)

1000 g (12.3 mol of formaldehyde) of a 37% aqueous formalin solution are heated together with 10 g (0.27 mol) of lead (II) acetate and 50 g of the co-catalyst from Example 1 to the reflux temperature. Then the heating bath is removed and piperidine is slowly added so that the mixture continues to boil on its own. After 85 minutes, the residual formaldehyde content dropped to 1.8%. The reaction is stopped by cooling.

Consumption of piperidine: 58 g.

After concentration in a water jet vacuum, 401 g of a 1.7% water-containing mixture of polyhydric alcohols, hydroxyaldehydes and hydroxyketones with a content of reducing components, calculated as glucose, of 47.7% and a viscosity at 50 ° C. of 21565 mPa.s and an OH number of 668.

The example shows that when a secondary amine is used, longer reaction times are required for the formaldehyde condensation, and that the base consumption is higher and the yield of reducing sugars is poor, both of which demonstrate that Cannizzaro reactions have occurred to a considerable extent.

Example 5 (comparison)

1000 g (12.3 mol of formaldehyde) of a 37% aqueous formalin solution are heated to reflux temperature together with 10 g (0.27 mol) of lead (II) acetate and 50 g of the co-catalyst from Example 1. Then the heating bath is removed and morpholine is slowly added so that the mixture continues to boil on its own. After 45 minutes, the residual formaldehyde content dropped to 2.7%. The reaction is stopped by cooling. Morpholine consumption: 60 g.

After concentration in a water jet vacuum, ₃₈₂ g of a 3.7% water-containing mixture of polyhydric alcohols, hydroxyaldehydes and hydroxyketones with a content of reducing components, calculated as glucose, of 48.8% and a viscosity at 50 ° C. of 1379 mpa.s and an OH number of 611.

Example 6 (comparison)

1000 g (12.3 mol formaldehyde) of a 37% aqueous formalin solution are heated to reflux temperature together with 10 g (0.27 mol) lead (II) acetate and 50 parts of the cocatalyst from Example 1. Then the heating bath is removed and 2- (2-aminoethylamino) ethaol-1 is metered in slowly, so that the mixture continues to boil on its own. After 55 minutes at a _pH value from 5.7 to 6.2, the formaldehyde residual content has fallen to 3.3%. The reaction is stopped by cooling. Amine consumption: 68 g.

After concentration in a water jet vacuum, 358 g of a 2.9% water-containing mixture of polyhydric alcohols, hydroxyaldehydes and hydroxyketones with a content of reducing components, calculated as glucose, of 46.4% and a viscosity at 50 ° C. of 3069 mPa.s and an OH number of 70.3.

Claims (4)

1. Process for the preparation of low molecular weight polyhydroxyl compounds by self-condensation of formaldehyde hydrate in the presence of soluble or insoluble compounds of metals of the second to fourth main group or the second to eighth subgroup of the periodic system of the elements as a catalyst and, if appropriate, in the presence of compounds capable of endiol formation as a cocatalyst and / or of low molecular weight and / or higher molecular weight polyhydroxyl compounds, characterized in that the pH is controlled during the condensation reaction by the addition of 5 to 200 milliequivalents of a tertiary amine, based on 1 mol of formaldehyde. 2. The method according to claim 1, characterized in that amines are used which contain an electron-attracting heteroatom in the β-position to the tertiary nitrogen atom. 3. The method according to claim 1, characterized in that amines are used which contain an ether group and / or a further tertiary nitrogen atom in the 8-position to the tertiary nitrogen atom. 4. The method according to claim 1, characterized in that the tertiary amine N-methylmorpholine, N, N'-dimethylpiperazine or addition products with a molecular weight of up to 1000 of ethylene oxide and / or propylene oxide are used on morpholine or piperazine.