RU2453530C2 - Method of producing esters - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing esters of (C₁₅-C₂₂) fatty acids and (C₁-C₅) aliphatic alcohols, used as viscosity regulators for polyvinyl chloride compositions and industrial rubber articles. The method is characterised by that said compounds are obtained through re-esterification of a mixture of glycerine esters of C₁₅-C₂₂ fatty acids contained in renewable plant material with C₁-C₅ alcohols in molar ratio of oil to alcohol equal to 1:5, on alkaline catalysts, at temperature limited by the boiling point of alcohol, separating glycerine and then vacuum distillation, with output 95-98% of theoretical output with 95% oil conversion in 3 hours.

EFFECT: improved method.

1 cl, 2 tbl

Description

The invention relates to a method for producing fatty acid esters (C ₁₅ -C ₂₂ ) by transesterification of glycerol esters with C ₁ -C ₅ alcohols on alkaline catalysts. As the source of raw materials used renewable vegetable raw materials - vegetable oil.

These esters are used as viscosity regulators in polymer compositions, plasticizing additives.

For the modern polymer industry, modification of the physicochemical properties of polymers and products based on them is of great importance. Polymers themselves often do not possess the physicochemical properties necessary for molding products. To give the necessary operational properties, a large number of additives are introduced into their composition: stabilizers, plasticizers, lubricants and strength modifiers, flame retardants, antioxidants, light and heat stabilizers, and others. A very significant effect on the quality of polymers is exerted by viscosity regulators and plasticizing additives. Polymeric materials obtained with their use have high physical and mechanical characteristics.

Currently, not many substances are known that are used as viscosity regulators [1-5], for example, polyvinyl chloride plastisols [1], glycidyl ethers of poly (oxyalkylene) glycols [2]. Methods for producing monoalkyl ethers of mono- and diethylene glycols (ethyl, butyl cellosolves and carbitols), as well as propylene glycol monomethyl ether [3] are proposed. The viscosity regulator of polyvinyl chloride plastisol pastes obtained by compounding saturated acyclic hydrocarbons with alkyl phenols [4].

Common disadvantages of the known solutions are the shortage of raw materials and product instability; the difficulty of obtaining; non-environmental production; low flash points (<150 ° C); limited compatibility with polymers.

A known method of producing esters of dicarboxylic acids C ₂ -C ₆ and alcohols C ₅ -C ₆ based on waste products of caprolactam production [5]. The resulting mixture of esters has high plasticizing properties, flash point> 185 ° C, can be used as a plasticizer and diluent for PVC compositions, rubber products. However, due to the fact that the starting material is caprolactam production waste, the resulting product has a dark color and limited use in color and smell; cannot be used in the manufacture of building materials, such as linoleum.

The problem to which the invention is directed is the creation of a method for producing a mixture of esters used as a wide-profile viscosity regulator that meets environmental and technical requirements from renewable plant materials.

The technical result is the development of a method for producing esters of alcohols C ₁ -C ₅ and fatty acids C ₁₅ -C ₂₂ based on renewable plant materials. The problem is solved by transesterification of glycerol esters of fatty acids contained in vegetable oil, aliphatic alcohols C ₁ -C ₅ on alkaline catalysts.

where R ₁ = C ₁₅ -C ₂₂ ,

R ₂ = C ₁ -C ₅ .

The process was carried out in excess of alcohol with a molar ratio of oil: alcohol = 1: 5. The catalyst (KOH or NaOH) was taken at the rate of 1% by weight of the oil. The reaction was carried out in a flask with a stirrer at temperatures close to room temperature (20-30 ° C). Potassium hydroxide was dissolved in alcohol, and then oil was added. Stirring was carried out for about 3 hours. After a short sedimentation, the reaction mass was divided into two layers: glycerol (lower) and ether (upper). After separation from glycerol, the ether layer was washed with water acidified with phosphoric acid until a pH of about 7 was obtained. Further, from the organic mass by vacuum distillation the product — fatty acid esters — was distilled off.

The temperature does not significantly affect the process and is limited by the boiling point of alcohol. In the case of methanol and ethanol, the reaction can be carried out at room temperature. When choosing the optimal process conditions, the ratios of the reactants and the amount of catalyst are important. There were 12 syntheses with methanol at 30 ° C with different ratios of reagents and different amounts of catalyst (table 1). As a result, the conversion of ≈95% oily was achieved at different time intervals from 2.5 to 7.5 hours.

Table 1 The reaction time in hours to achieve a conversion of ≈95% oily The molar ratio of oil: alcohol The amount of catalyst by weight of oil 0.5% one% 1.5% 2% 1: 3 7.5 6 6 7 1: 5 6 3 3 four 1:10 4,5 2.5 2.5 3

As can be seen from table 1, with an increase in the amount of catalyst from 0.5 to 1% by weight of the oil, the speed significantly increases, and the reaction time decreases. With a further increase in the concentration of the catalyst, speed changes do not occur.

The increase in excess alcohol in relation to the oil from three times to ten times reduces the reaction time by more than 2 times (at a catalyst concentration of 1-1.5%). However, a large excess of alcohol is undesirable, because it needs regeneration after the reaction and recycling. Moreover, when changing the ratio of oil: alcohol from 1: 5 to 1:10, there is no more than a half-hour reduction in reaction time.

Thus, the optimal process conditions are the ratio of oil: alcohol = 1: 5 (molar) and the concentration of the catalyst is 1% by weight of the oil. Under these conditions, in 3 hours, the yield of esters is 95-98% of theory at 95% conversion of the starting oil.

The waste is the glycerol-methanol fraction. After distillation, methanol is returned to the process, and glycerol after purification can be used as a product for technical purposes.

The resulting viscosity regulator has a transparent color, odorless, hazard class 4. Indicators:

molecular mass ~ 300 g / mol flash point in open crucible not lower 172 ° C density at 20 ° C 0.88 g / cm ³ saponification number 185 mg KOH / g

According to the main indicators, it corresponds to domestic and foreign samples of viscosity regulators used in the production of linoleum (table 2).

table 2 Comparative characteristics of viscosity regulators Indicators BYK-LP R21151, Germany Vegalon RV-M, Russia The inventive viscosity regulator Density at 20 ° C, g / cm ³ 0.87 0.75-0.85 0.8-0.9 Flash point in open crucible, ° C 140 155 172 Viscosity mm ² / s n / a 115 10-20 2-5 Acid number, mg KOH / g There is no data 10 5

Since the result obtained in comparison with the described results is not known, the proposed solution meets the criterion of "inventive step".

Information sources

1. RF patent No. 2017756, publ. 03/26/1992

2. RF patent No. 2084454, publ. 06/22/1995 g.

3. RF patent No. 2111988, publ. 02/07/1994

4. RF patent №2149865, publ. January 12, 1999

5. RF patent No. 2373188, publ. December 4, 2007

Claims (1)

A method of producing esters of fatty acids (C ₁₅ -C ₂₂ ) and aliphatic alcohols (C ₁ -C ₅ ) used as viscosity regulators of polyvinyl chloride compositions and rubber products, characterized in that they are obtained by transesterification of a mixture of glycerol esters of fatty acids C ₁₅ - C ₂₂ contained in vegetable renewable raw materials, alcohols C ₁ -C ₅ at a molar ratio of the alcohol-oil ratio of 1 ÷ 5, in an alkaline catalyst at a temperature that is restricted to the boiling temperature of alcohol, separation of glycerin and subsequent vacuum by distillation, with a yield of 95-98% of theory with a conversion of 95% oil, for 3 hours.