SU583740A3 - Method of preparing dipropyleneglycoldi-benzoate - Google Patents

Description

one

The invention relates to an improved process for the preparation of dipropylene glycol dibenzoate, which can be used as a plasticizer, for example, for vinyl acetate compositions.

A known method of producing dipropylene glycol dibenzoate by reacting benzoic acid with dipropylene glycol at 255 ° C in an inert atmosphere.

The yield of the target product is 90-91% in terms of dipropylene glycol. Chromaticity poyodnoy scale 58.

However, the low purity of the target product does not allow it to be used as a plasticizer for color compositions.

The purpose of the invention is to increase the frequency and yield of the target product, achieved by the fact that dipropylene glycol is treated with methyl benzoate in the presence of a catalyst of the general formula (RO) X, where is alkyl; X is aluminum or a SiOAECOR group in which 1 has the above value at 150-2 ° C in an inert atmosphere with

the subsequent selection of the target product.

The yield of the target product is 98%, chromaticity on the iodine cupboard 1.

The original methyl benzoate is a by-product of dimethyl terephthalate production.

Methyl benzoate containing impurities is used in at least 2 mol (based on the content of methyl benzoate) per 1 mol of dipropylene glycol.

A slight excess (up to 25 mol.%) Of methyl benzoate contributes to a more rapid reaction.

In the industrial production of rimethyl terephthalate, methyl benzoate containing less than 80 wt.% Of the basic substance is obtained. By simple distillation, it is enriched to at least 80% by weight.

The concentration of the catalyst should not exceed 0.8 weight. %, usually it is O, 02-O, 5, preferably O, O50, 2; weight. % relative to the total amount of methyl benzoate and dipropylene glycol

KOLYA. When the initial mixture of cni -.- iafia is heated, small amounts of jjei4cuj: eTy of their compounds and aodes are distilled off. When tteercn cleavage of methanol. During the transesterification of the reaction, the reaction is continuously increased. It is advisable to carry out the transesterification in an inert atmosphere, for example, under the aetome ™. If the initial methyl benzoate contains insignificant amounts of free acids, then the final product with the corresponding HM acid number is treated with BOY alkaline solutions. And & Achita. The l.-part of highly volatile substances can be removed when the air is blown for steam. EXAMPLE IA In a 10 liter flask, ciia6, a female mecapcount of a recipe, a COLUMN filled with a pair of PY shiga rings, and a nitrogen inlet pipe, heat 2144 weight, h (16 mol) dcpropylene, and 5227 weight.h technical meggnieiaoat (frequency 93.6 wt.%. 36 mol of basic substances) D in the presence of 7.4 wt.h. (OD wt.% In terms of the reference quantity of the initial components) the city of | - bu-tilata aluminum. With a flask temperature of up to 1 € - 0 ° C, it is easy to use volatile compounds and water. Pro 160 ° C starts a methane release.

Catalyst

Title

Etilate alumshsh

Also

1-2

O.t)

Oh, about

Single In the course of 5 hours TGMimnaTvna in a flask, the PSH value is up to 24 ° C. During this time, the SNCN: 11 is removed from methanol. The purity of the plant is 95% (according to r-epilm gas; chromatography). Balance;:; ; yy impurities; located in the original. /; and; em: -: l benzoate. Low-boiling substances and excess, the methylbepzozoate is discharged in vacuum (20 mmHg stl at 200 ° C. Dipropylene glycol dibenzoate (98% yield in terms of dilropylene glycol) has an acid number of 1.6, igglenium number of 326 (5 (according to the theory 328 ) to color (by iodine scale) 3.0. After ochazhdedey up to 150 ° C ozopirovat for 30 minutes (apparatus type 2; firm PreiiTOKcf Hamburg, Germany, productivity Ij5 g ozone / hour at 12 kV and 80 W) After ozonization into the atmosphere is equal to 3., and after treatment with an aqueous alkaline solution - 2. Acid number of the final product Os3; Omyleni 329.5, Example 2, Under the conditions of example 1, using 5818 parts by weight (40 mol JKCToro of the compound) methylbenzoate of the same purity after 4 hours with a yield of .98j5% (calculated as d d gropropiclicle) i- - ° C 1) a gallium product whose qualities are identical to the qualities of the substance synthesized by 0 example J., Example 3. As in example 1, the target product is obtained in the absence of various catalysts with yield 97 of 5-98.5% (s recalculated dipropylene glycol). The results are shown in the table.

n-Pr01shlat aluminum

Aluminum isopropyl

(CjNgOjSiOAEiOC H)

1-2

4.5

4.0 5.0

Claims (1)

2 558 Similar results are obtained when using other alkoxides of aluminosilicon as a catalyst. PRI me R 4. Conducted, the experience is analogous to example 1, but in the presence of 7.2 weight.h. methylate aluminum as a catalyst. After 4.5 hours of reaction, the yield is 97% (in terms of dipropylene glycol). After ozonation and treatment with an aqueous alkaline solution, the acid number of the product is below 1, color 1-2 (i.e., the product is completely colorless). Invention A method for producing dipropylene glycol dibepzoate using diipropylene glycol when heated in an inert atmosphere with Bbj separation of the target product, characterized in that, in order to increase the purity, and the yield of the target product, dipropylene glycol is reacted with a methyl benzoate in the presence of a catalyst of general formula () X, where T -C -dalkyl; X is aluminum or Si group ODE COR), in which R has the above value.