DE1057083B - Process for the preparation of 2,2-dimethylpropanediol-1,3 - Google Patents

Description

GERMAN

PATENT OFFICE

INTERNAT KL. C 07 C

I'il ^€

EXPLAINING EDITORIAL 1057 083

B 45176 IVb / 12 ο

JULY 2, 1957

REGISTRATION DAY:

NOTICE
THE REGISTRATION
AND ISSUE OF THE
EDITORIAL: 1 4th MAY 1 9 5 9

The formation of 2,2-dimethylpropanediol-1,3, the so-called neopentyl glycol, from isobutyraldehyde and formaldehyde via the intermediate stage of formisobutyraldol has been in the literature for a long time known. This synthesis has only recently become technically interesting after isobutyraldehyde was made accessible by oxy- gen of propylene.

The conversion of the formisobutyraldol to neopentyl glycol can take place in various ways, z. B. by pressure hydrogenation according to US Pat. No. 2,400,724, with. the implementation encounters certain difficulties in practice. Another possibility of neopentyl glycol formation is given by the Cannizzaro reaction between the formisobutyraldol and formaldehyde, the is triggered by molar amounts of basic substances.

The second route can also be used in one production stage from isobutyraldehyde to crude Neopentyl glycol. The greatest difficulties with this procedure are the many possible ones Side reactions that occur both in the first step of the aldol ation and in the second, the Cannizzaro reaction occur and which are well known from the specialist literature. These many possible Side reactions that appear to a greater or lesser extent depending on the process conditions occur, reduce the yield considerably.

Z. B. a temperature increase above 60 ° C, which is slightly due to the strongly exothermic Reaction can occur. If overheating is avoided by appropriately dosed inflow of the Caustic solution leads to unacceptably long reaction times. On the other hand, if you try additional To avoid external overheating, there will still be local overheating of the Base addition point, reducing quality and exploitation works. Taking these relationships into account, the technical implementation so far only varying yields of neopentyl glycol of 75 to 83% of theory achieved will.

It has now been found that the secondary and secondary reactions can be suppressed and good yields of 2,2-DimethylpropandioI-l, 3 is obtained when the reaction is carried out by adding a phase-forming The substance in the inhomogeneous system.

The process is carried out at room temperature or at moderately elevated temperatures, e.g. B. up to 65 ° C. In this mode of operation, the phase ¹ -forming substance absorbs the isobutyrakiehyd and some of the formaldehyde. The first step of the reaction, the aldol reaction triggered by the catalytic elongation of bases, takes place in the organic layer with constant addition of the process for the production of 2,2-dimethylpropanediol-1,3

Applicant:

Aniline & Soda Factory in Baden

Corporation,

Ludwigshafen / Rhine

Dr. Erich Haarer and Dr. Karl Ruh],

Ludwigshafen / Rhein, have been named as inventors

Formaldehyde from the aqueous layer, and the Formisobutvraldol formed, ve rbleibt completely in the oil layer. The second step of the reaction that

Cannizzaro reaction, which occurs with continuous or batchwise addition of molar amounts of Lye takes place, now runs off in a mild form at the phase boundary layer, since the lye comes from the water layer only at the phase interface with the shape

isobutyraldol and the formaldehyde reacts.

In the previously known processes in which the

Quantity ratio between water and organic

Substances in the reaction mixture is comparable, finds

the reaction takes place practically in a homogeneous system,

because the inhomogeneous Mixture of water and the organic reaction components already after adding 7% of the total alkali required for the implementation Mch homogenized.

Phase formers in the context of the invention are organic Solvents in which formaldehyde, isobutyraldehyde and formisobutyraldol are readily soluble, while their dissolving power to water is low. It is advantageous to use z. B. Alcohols

the carbon number 5 to 7. In the case of the lower alcohols, the water solubility is too great; higher Alcohols, on the other hand, have too little power to dissolve the reaction mixture. One can but also ether, e.g. B lower ethers or chlorine

hydrocarbons, such as B. methylene chloride. Use.

The formaldehyde is expediently in the form of his; aqueous solutions, e.g. B. a 30% solution applied.

-. 909 510 / 4-58

Claims (1)

After the reaction has ended, most of the neopentyl glycol formed is in the upper oily layer, whereby the further processing and separation of the waterless salts, mainly formats. is facilitated. The work-up of the reaction product on neopentyl glycol can, for example, take place by phase separation. The phase-forming ones added before implementation Fabric can be made from the separated 01 layer distill off and then the remaining crude neopentyl glycol by distillation Purify under reduced pressure, let this distillation Expediently, at least - o much water or steam is added. than to \ ermeidum the crystallization in the cooler of the apparatus is required will. From the distilled X * eopent \ lg'h kol water (icmisch the water can be removed by heating in a vacuum. To a further Purification, the evaporation residue can optionally be recrystallized. The yield of formed Xeopentvlgh kol is increased by carrying out the reaction in the inhomogeneous S \ star 10 to 12 ⁰ At the inventive shaped nacli method can be reached values of 93-05% of theory i. The minimal discoloration of the fud product observed so far is avoided. Example In a stirred kettle with a capacity of 800 liters. which is flushed with nitrogen before start-up, 61.2kg isobutyraldehyde (.850AJoI) 170kg 30% formaklelud "(1700 mol), 208 kg isoamyl alcohol (a mixture of 2-methylbutanol-1 and 3-a! eth_ \ lbutanol 1 with a boiling range of 128 to 132 ^C C) and 4528 g of 25 ^N sodium hydroxide solution are added with vigorous stirring within \ '-> hour. The aldolization raises the temperature from an initial value of 10 to 40 "C. Half a One hour after the addition of the sodium hydroxide solution is complete, a further 65,736 kg of 50% sodium hydroxide solution are added in portions over the course of 4 hours. Care must be taken that the temperature in the mixture does not rise above 65 ° C. The mixture is then stirred for 3 hours and cooled and neutralized with dilute sulfuric acid. The separation of the two phases gives 300.8 kg of UN layer and 218.4 kg of water layer. The two layers are worked up separately. a) Oil layer. Under reduced pressure (380 mm Hg), the Ülpbase contains 202.14 kg of water Isoamyl alcohol and 15.46 kg of water (as an underlayer) distilled off The residue from this distillation is overdistilled at 380 mm Hg to remove salt residues with the continuous addition of \ V; i ^ ht. wherein the Xeopent} lglycol together with passes over the water. AN residue remain 4.2 kg of salts. The water-containing XeopetiU lglycol is then under reduced pressure at 380mm Hg dehydrated by slow heating to 130 "C and drained the melt. In this way, a total of 77.0 kg of pure xeopeiitylglycol is obtained Oil layer, if the tensioiismaßig through W'a ^ er and Tsoarm lal'kohol recovered amounts carried over by redistillation. I)) Y water layer. The water layer is extracted in a Fxtraktioiisapparat with diethyl ether, the Ether is distilled off and the residue is obtained by adding water distilled to separate off the salts under reduced pressure. The distillate, which is made from pure xeopentyl glycol and water exists, becomes in the \ akuum drains. 6.4 kg of pure xeopeiityl glycol are obtained. The < iesame thaw prey on Xeopenn lglycol is therefore 83.4 kg. (1 h 04.3 "/ 0 der Theoiie ' If the same experiment is not carried out the same Amount of starting materials, however, without the addition of Isoamyl alcohol. · Η one gets 307.5 kg one homogeneous aqueous solution. By hxtrakt'on with l) iath \ lather and distillation one receives 73.8 kg xeopeut) lglycol. giving a yield of 83.48% of the Theor'e corresponds. P \ 1 l. \ I W-ii \; 1 (il Process for the preparation of 2,2-dimethylpropanediol-1.3 by converting aqueous Formaldeln dlosuiigen with isobutyraldehyde in Presence of molar amounts of basic substances, thereby characterized in that the reaction is carried out by adding a substance which forms pliases in the inhomogeneous S \ star performs. O 909 510/458 5. 59