RU2149865C1 - Method of synthesis of alkylene glycol monoalkyl esters - Google Patents

Abstract

FIELD: organic chemistry, chemical technology. SUBSTANCE: invention relates to method of synthesis of monoalkyl esters of mono- and diethylene glycols (ethyl-, butyl-cellosolves and carbitols) and propylene glycol monomethyl ester that are used in production of solvents, plasticizers, components for low-freezing, deicers, hydraulic and hydraulic break liquids and for production of materials used in industry of plastics, pesticides, lacquers and dyes. Method of synthesis of alkylene glycol monoalkyl esters is carried out by interaction of ethylene and propylene oxides with alcohols at increased temperature and pressure and involves the use of organic compounds of metals of fifth and/or sixth group of periodic system of elements as catalyst, preferably organic compounds of vanadium, molybdenum and tungsten and more precisely: alkyl esters of corresponding to inorganic acids. Method provides high selectivity of process at decreased alcohol excess (by 4-8-fold) with respect to alkylene oxide, producing concentrated solutions of the end compounds (above 20 wt.-%). EFFECT: improved method of synthesis, decreased energy consumption. 1 cl, 2 tbl, 11 ex

Description

 The invention relates to a method for producing monoalkyl esters of mono- and dialkylene glycols, in particular to a method for producing methyl, ethyl, butyl cellosolves and carbitols, as well as monoalkyl ethers of propylene glycol.

 Monoalkyl ethers of alkylene glycols are used in the manufacture of solvents, plasticizers, components for low-freezing, anti-icing, hydraulic and hydraulic brake fluids, as well as for the production of materials used in the industry of plastics, pesticides, varnishes and paints.

 A known method of producing monoethyl ether of ethylene glycol (ethyl cellosolve) and monoethyl ether of diethylene glycol (ethyl carbitol) by the interaction of ethanol and ethylene oxide at elevated temperature and pressure in the presence of a catalyst - sodium hydroxide (Dyment O.I. et al. Glycols and other derivatives of ethylene and propylene oxides. - M .: Chemistry, 1976; Malinovsky M.S. Oxides of olefins and their derivatives .-- M .: Goskhimizdat, 1961).

 The disadvantage of this method is the low selectivity of the formation of the target products. At a molar ratio of oxide: alcohol = 1: 5, the selectivity for the formation of ethyl cellosolve does not exceed 51.3 mol%, ethyl carbitol - 13.9 mol%.

The closest analogue of this method is a method for producing monoalkyl ethers of alkylene glycols by reacting ethanol and ethylene oxide and propylene glycol monomethyl ether at elevated temperature and pressure in the presence of a metal-containing catalyst — a molybdenum-containing bottoms residue after distillation of the products of epoxidation of C ₃ -C ₅ olefins with organic hydroperoxide or water the remainder (Patent of Russia N 1203846, priority 28.10.81).

 The disadvantage of this method is that high selectivity (for ethyl cellosolve 63.7-83.4 mol%, ethyl carbitol 3.24-16.6 mol%, propylene glycol monomethyl ether 95.1 mol%) is achieved by carrying out the process at a large 8-10-fold molar excess of alcohol relative to the oxide. This leads to the preparation of dilute solutions of the target products (less than 20% wt.) And, in turn, requires increased energy consumption for their allocation.

 The proposed method allows to achieve high selectivity by using a smaller excess of alcohol (4-8-fold) in relation to alkylene oxide, to obtain concentrated solutions of the target products (more than 20% wt.) And, as a result, reduce energy consumption at the separation stage.

 This result is achieved by the interaction of ethylene oxide and propylene with alcohols at elevated temperatures and pressures and the use of fifth and / or sixth group metals of the Periodic Table of Elements as catalysts for organic compounds. Preferably, organic compounds of vanadium, molybdenum and tungsten are used as organic compounds of metals of the fifth and / or sixth group of the Periodic system of elements. Preferably, alkyl esters of the corresponding inorganic acids are used as organic compounds of vanadium, molybdenum and / or tungsten.

 The following examples illustrate the method.

Example 1
In a 200 ml metal ampoule equipped with a jacket for heating with a coolant, a valve for loading reagents and unloading reaction products, 92 g (2 mol) of ethanol, 22 g (0.5 mol) of ethylene oxide and 0.1 g of catalyst are sequentially loaded bis (ethanediol-1,2) molybdate. The molar ratio of oxide: alcohol = 1: 4. The molybdenum content in the initial reaction mixture is - 0.005% wt.

The ampoule is placed on a laboratory rocking chair and connected to a thermostat with a temperature of 120 ^o C, create a pressure of 20 MPa. After 2 hours, the oxide conversion is 100%.

The total concentration of the target products (cellosolve and carbitol) in the reaction products (C _cp ) was 36.7% wt. The selectivity of the formation of ethyl cellosolve (per converted oxide) Ф ₁ is 77.0 mol%, ethyl carbitol Ф ₂ - 21.4 mol%, other glycols (ethylene glycol, diethylene glycol, triethylene glycol monoethyl ether) Ф ₃ - 1.6%.

Examples 2-5
The process is carried out analogously to example 1 with other molar ratios of oxide: alcohol, with different contents of molybdenum in the initial reaction mixture, as well as under different conditions of the process of hydroxyethylation. The process conditions and the results are shown in table 1. Table 1 also shows the results of testing the catalysts in the synthesis of ethylene glycol monobutyl ether (butyl cellosolve) and diethylene glycol monobutyl ether (butyl carbitol) - examples 4-5.

Examples 6-10
The process is carried out analogously to example 1 when using other catalysts, a temperature of 110 ^o C, a pressure of 20 MPa, the metal content in the initial reaction mixture of 0.01% wt. and a molar ratio of ethanol: ethylene oxide = 6: 1. The process is carried out until the oxide is completely converted within 2-3 hours. The process conditions and results are shown in table 2.

Example 11
The process is carried out according to the procedure described in example 1. 96 g (3 mol) of methanol, 29 g (0.5 mol) of propylene oxide are sequentially loaded into a metal ampoule and 0.15 g of bis (propanediol-1,2) as a catalyst molybdate. The molar ratio of oxide: alcohol = 1: 6. The molybdenum content in the initial reaction mixture is - 0.007% wt.

The ampoule is placed on a laboratory rocking chair and connected to a thermostat with a temperature of 95 ^o C, create a pressure of 15 MPa. After 1 hour, the oxide conversion is 100%.

The concentration of the target product (propylene glycol monomethyl ether) in the reaction products was 35.8% wt. The selectivity of the formation of the target product (per converted oxide) Ф ₁ is 96.9 mol%, dipropylene glycol monomethyl ether Ф ₂ - 3.2 mol%. Other glycols (propylene glycol, dipropylene glycol, tripripylene glycol monoethyl ether) were found in trace amounts. Propylene glycol monomethyl ether consists of 64.5% of a compound with a secondary OH group.

 Thus, the proposed method while maintaining high selectivity allows to increase the concentration of target products in the reaction mass from 20% wt. up to 21-36.7% wt. and, as a result, reduce energy costs at the stage of allocation.

Claims (3)

 1. The method of producing monoalkyl ethers of alkylene glycols by the interaction of alkylene oxides with alcohols in the presence of metal-containing catalysts at elevated temperature and pressure, characterized in that the process is carried out in the presence of organic compounds of metals of the fifth and / or sixth group of the Periodic system of elements.  2. The method according to claim 1, characterized in that the organic compounds of metals of the fifth and / or sixth group of the Periodic system of elements use organic compounds of vanadium, molybdenum and tungsten.  3. The method according to claim 2, characterized in that the organic compounds of vanadium, molybdenum and / or tungsten use alkyl esters of the corresponding inorganic acids.

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