JPS61145137A - Production of polyglycerol - Google Patents

Abstract

PURPOSE:To produce a polyglycerol having light color in an easily purifiable state, by adding glycidol of a molar number corresponding to the polymerization degree of the objective compound to a carboxylic acid such as formic acid, acetic acid, etc., and hydrolyuzing and decarboxylating the addition product. CONSTITUTION:Glycidol of a molar number corresponding to the polymerization degree of the polyglycerol to be produced is added to a carboxylic acid of formula RCOOH (R is H or 1-5C alkyl) (e.g. formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, etc.), and the obtained polyglycerol carboxylate is hydrolyzed with water and then decarboxylated to obtain a polyglycerol. The product can be purified easily by neutralizing the residual carboxylic acid completely with an alkali, dehydrating and precipitating the product, adsorbing the precipitate to diatomaceous earth, etc., and filtering the adsorbed product. USE:Emulsifier for food, humectant for cosmetic, and raw material of plasticizer, surfactant, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyglycerin with little coloring.

Polyglycerin is used as a raw material for food emulsifiers, cosmetic moisturizers, plasticizers, surfactants, etc.

Conventionally, polyglycerin has been produced by recovering glycerin from distillation residue, dehydration condensation of glycerin, or direct synthesis from epichlorohydrin, but polyglycerin produced by these methods is difficult to purify. Further, there were drawbacks such as severe coloring and a wide range of polymerization degree distribution.

In addition, in the addition polymerization of glycidol to glycerin, alkali hydroxide, amine, etc., which are ring-opening catalysts for epoxy groups, are generally used, but polyglycerin produced by this method is also difficult to purify and tends to be colored. It had the disadvantage of being harsh.

Therefore, the inventors of the present invention conducted extensive research to establish a method for producing polyglycerin that is less colored and easier to purify.
The present invention has now been completed.

The present invention is as follows. That is, l) Addition reaction of glycidol in the number of moles corresponding to the degree of polymerization of the target product to the carboxylic acid in the general formula below to synthesize polyglycerol carboxylate, followed by hydrolysis, followed by decarboxylation. A method for producing polyglycerin, characterized in that:

RCOOH (A) Here, R represents hydrogen or an alkyl group having 1 to 5 carbon atoms.

2) The carboxylic acid of the general formula is one or more acids selected from formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, and caproic acid. Method ①, Addition Reaction Step (Esterification) The amount of carboxylic acid used is determined by the ratio to glycidol depending on the degree of polymerization of the polyglycerin to be obtained. That is, in order to obtain polyglycerin in the monomeric form, 1 mol of glycidol is required for 1 mol of carbonate.

The addition reaction usually involves placing the carb/acid in a reactor;
This is done by adding glycidol little by little while stirring.

The reaction temperature is 8% until the amount of glycidol added is a specified amount.
0 to IIQ"C, and then at 110 to 230"C, preferably 120 to 140"C.

If the reaction temperature is 110'C or higher in the first stage, the product polyglycerin will be severely colored, and if it is 80C or lower, the reaction rate will be slow. If the reaction temperature in the latter stage is less than 110°C, diglycerin etc. will increase, the degree of polymerization will range over a wide range, and the temperature will exceed 230"C.
If it exceeds this amount, side reactions occur due to decomposition of glycidol, which is not preferable.

The completion of the reaction is judged when the conversion rate of glycidol is 99% or more. Furthermore, the reaction rate can be further increased by adding an acid catalyst such as phosphoric acid as a catalyst.

(2) Hydrolysis step (decarboxylation) Hydrolysis is usually carried out by adding water to the polyglycerol carboxylate, hydrolyzing it, and then distilling water and carboxylic acid off under reduced pressure.

The amount of water added is 0.5 to 2.0 parts by weight based on the intermediate,
Further, the reaction temperature is 100 to 120°C, and the appropriate time for 1 hour is 3 to 5 hours.

Further, these reactions are preferably carried out under an inert gas such as nitrogen gas, and may be pressurized if necessary.

The product thus obtained can be easily purified by completely neutralizing the residual carboxylic acid with an alkali, dehydrating and precipitating the product, adsorbing the precipitate onto diatoms, etc., and distributing it from house to house. The target polyglycerin has very little coloration (and has a higher degree of polymerization than is suitable for the purpose. However, depending on the purpose, there is no need to purify it if there is no problem with the mixture of polyglycerin carboxylic acid esters in the product polyglycerin. .

According to the present invention, it is possible to determine the concentration of the target polyglycerin by adding only glycidol on the basis of carb/acid, and further to eliminate harmful substances by passing through the intermediate polyglycerin carboxylate. can.

Next, the present invention will be explained by giving examples, but the present invention is not limited to these.

Example 1 42g of acetic acid (0,
7 mol) was replaced with nitrogen gas, heated to 90'C for 3 hours with stirring, and then gradually heated to 13
All of 311 gr of glycidol (4.2 mol) was added dropwise at 0°C for 2.5 hours, for a total of 5.5 hours. The temperature was maintained for an additional 2 hours.

Then cooled to io o °C to 170 gr + 7)
After adding water and stirring for 3.5 hours to cause hydrolysis, water and acetic acid were removed under reduced pressure to obtain 339g of crude polyglycerin, which was mostly colorless and transparent, Gardner 1 It was below.

Next, take 200g of the above crude polyglycerin and
% hydroxide) Add 35g of IJum aqueous solution and heat at 90°C.
After stirring for 1 hour at 20-5 Torr100-11
Dehydrated at 0°C. Cool to 90°C and remove as adsorbent.
．． After adding 16 g of diatomaceous earth and stirring for 1 hour, it was filtered to obtain 190 g of purified polyglycerin. The hue was almost colorless and transparent, Gardner was less than 1, the hydroxyl value was 966, and the average degree of polymerization was 6.

Comparative example 50071! / In a flask with a stirrer, 9.2 g r
(1,0 mol) of glycerin and 2.4 gr of 50
Take a % sodium hydroxide aqueous solution and replace it with nitrogen gas.
Dehydration was performed under reduced pressure while heating and stirring at 0°C.

Subsequently, the temperature was maintained at 115°C to 125°C and 370gr (5,
0 mol) of glycidol was used in 3 hours. After keeping the above temperature for another 2 hours, unreacted glycidol was removed under reduced pressure, resulting in 456g of crude polyglycerin.
I got it. Its hue was light brown and Gardner 8.

Next, add 25% of a 10% acetic acid aqueous solution to the above crude polyglycerin.
gr, heated to 80°C to 90°C and stirred for 1 hour, then heated at 10 to 5 Torr and 110°C to 120°C for 1 hour.
Dehydrated for hours. Cool to 90°C and use as an adsorbent for 0.2
Add gr of diatomaceous earth, stir for 1 hour, and filter.
4 gr of purified polyglycerin was obtained. Its hue was light brown, Gardner was 7, hydroxyl value was 965, and average degree of polymerization was 6.

Example 2: Except for using 61.6 gr of butyric acid (0.7 mol),
It was reacted and purified in the same manner as in Example 1.

The hue of the obtained purified polyglycerin 190g is almost colorless and transparent, Gardner is less than 1, and the human xyl value is 96.
4, average degree of polymerization was 6.

Claims (1)

[Claims] 1) Polyglycerin carboxylate was synthesized by adding glycidol in a molar number corresponding to the degree of polymerization of the target product to a carboxylic acid represented by the following general formula (A), and then hydrolyzed. A method for producing polyglycerin, which is then subjected to decarboxylation. RCOOH...(A) Here, R represents hydrogen or an alkyl group having 1 to 5 carbon atoms. 2) Claim 1, wherein the carboxylic acid of general formula (A) is one or more acids selected from formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, and caproic acid. The method described in section.