CS273760B1 - Method of metacrylic acid's monoester and ethylene glycol or diethylene glycol continuous refining - Google Patents

Abstract

A method of continuous refining of monoester of methacrylic acid and ethylene glycol or diethylene glycol, where the raw monoester is brought into intensive counterflowing contact with an organic solvent of alkane type by means of vibratory movement and then a solvent of ether type or higher ketones, also by means of vibratory movement, based on the fact that the liquid phase from re-esterification is brought into intensive counterflowing contact with a solvent of alkane type containing at least 30 % by weight monoester, to which is added 50 to 150 ppm inhibitor of phenol type, best p-methoxy phenol, further, that the organic phase, of alkane type, after contact with the liquid phase from esterification, is brought into intensive counterflowing contact by means of vibratory movement with water containing 50 to 150 ppm inhibitor in a mass ratio of water flow to organic phase of 1 : 0.5 to 1 : 4, preferably 1 : 2.5, whereupon the occurring aqueous solution is joined with the liquid phase from esterification, further, that the aqueous phase, after counterflowing contact with the solvent of alkane type, is mixed again with the inhibitor of phenol type into a solution containing 50 to 150 ppm, preferably 100 ppm inhibitor, whereupon this aqueous phase is bought into the same counterflowing contact by means of vibration with the oxygenous solvent of ether type or higher ketone.

Description

The invention relates to the continuous refining of monoesters of mstacrylic acid with ethylene glycol (substance I) or β diethylanglycol (substance II).

GS 273760 Bl

CH 2 -C 1 ch ₃ COOCHg - CH ₂ - OH (AND) CH - C - C00CH ₂ - CH _2-0 - (CH _{2) 2} - OH (II) CH ₃

which result from the re-esterification of the N-methyl ether of methacrylic acid with ethylene glycol or dletylene glycol from the catalytic action of alkali metal alcoholates or quaternary ammonium bases. and the undesirable reaction by-products, methanol and the diester of the corresponding glycol with methacrylic acid.

According to the existing methods (see MS, author's certificate no. 253 633, no. 252 800, no.

269 926.1 δ »265 977) and the reaction product is first diluted with water in a weight ratio of 2 parts of product ι 1 part of water and the resulting aqueous solution is first brought into continuous countercurrent contact by vibration with alkanes or mixtures thereof, thereby removing the reaction product most unreacted motylastar of methacrylic acid and diester of methacrylic acid 9 by the appropriate glycolam. Further, the aqueous solution of the product is brought into intense countercurrent contact by vibration and an oxygen-containing organic, smear / like diethyl ether or higher cosolvent, such as motyl isobutyl ketone, thereby extracting most of the product and retaining the appropriate glycol in the aqueous solution. bringing the solution of the organic phase containing the product with a small amount of water into a continuous countercurrent contact by vibration and combining the recovered aqueous solution with the spraying of the aqueous phase until extraction with an oxygen-containing organic solvent. The drawbacks of the process are, on the one hand, that during the extraction of the reaction mixture with alkenes, the product is partially extracted and its losses are lost and the diester is incomplete. On the one hand, during the entire refining process, a certain quantity of product polymers is formed which can only be completely removed from the product β which, besides the losses, cause a deterioration of the product quality and fouling of the equipment.

Surprisingly, these deficiencies have been remedied by the method of the invention. It consists in that ,: introduced first undiluted reaction product crude monoastsr ^1, comprising at least 30%. ' monoesters, in intense countercurrent contact for vibration and alkanes or cycloalkanes ee of 6 to 10 carbon atoms by vibration, wherein the ee aqueous phase disperses into drops.

To the crude monoesters ae will add 50 to 150 ppm of a phenol type inhibitor, β preferably p-methoxyphenol. The ratio of the mass flow rates of the crude monoesters to the alkanes or cycloalkanes is 1 to 4 to 1 to 3 / preferably 1 to 0 to 75 to 1 sec. in addition to the undesirable by-products of a small number of monoesters, said in intensive countercurrent contact after vibration with water containing 100 ppm inhibitor at a ratio of water flow rates to organic phase of 1 s 0/5 to 1 and 4, β preferably 1 t 1/5 to 1 2.5, The obtained aqueous extract is combined with the crude monooster. The recovered aqueous raffinate after contacting the crude monoesters with alkanes or cycloalkanes is re-emission with the inhibitor to a solution containing 50 to 150 ppa inhibitor and brought into intense countercurrent contact from vibration with an oxygenated organic solvent. miscible with lead, preferably sterile or methyl isobutyl ketone / in the ratio of water to organic phase mass flow rates of 1 j 0/5 to 1 j 4 / preferably 1 t 0/5 to 1 j 1.5, obtained a solution of refined monoesters in organic solvent is brought into countercurrent contact by vibration and water in a manner known per se.

In this way, the extraction of alkanes or cycloalkanes is first achieved by removing from the crude monoesters the liophilic impurities, in particular the diester of the motacrylic acid diester, and

4 '

EN 273 760 Bl unreacted methyl methacrylate and ¹ EO small množotvi monoester passed into the organic phase by washing regenerate the extract with water, 'and then removed from the e monoeater in Water Strong soluble impurities rozpouátádlem oxygen extraction thereof. The last residual impurities are removed by washing the extract with water. In all stages of the process described, an inhibitor is added in aqueous solutions of the monoester, which tends to be limited to organic solvents to a limited extent. The refined monoeater is freed from the solvent by vacuum distillation, during which the polymerization is inhibited by the inhibition of the transition to the organic phase during extraction.

Example 1 liters of reaction amester after re-esterification containing 42% by weight of the formula I, i

6.8 wt. % diester, 12.2 wt. % methyl methacrylate / 7.7 wt. hexane and 31.3 wt.% ethylene glycol were subjected to countercurrent extraction with hexane (the raffinate being undiluted with an aqueous solution obtained by washing the hexone extract from the extraction). The volume ratio of water to organic (hexane) extract was 0/6 and the volume ratio of the injected liquid phase from re-esterification to organic (hexane) solvent was also 0/6. The liquid aqueous phase was subjected to extraction of methyl isobutylcotone with simultaneous washing of the water with water. The dried organic extract was concentrated on a vacuum film evaporator. The resulting product 2-hydroxyethyl ether of methacrylic acid of formula 1 contained 0/18 wt. diester, 0/21 wt. ethylene glycol. All four extraction steps were performed on a countercurrent extraction column and vibrating trays.

Example 2

3/8 liters of the reaction butter after re-esterification having a composition of 49 wt. % of formula IX, 9/2 wt. diester / 8/6 wt. % methyl methacrylate, 8/3 wt. % hexane and 24.9 wt. The diethylene glycol was subjected to countercurrent extraction as described in Example 1. The ground hexane was milled with n-hexane / hexane: cyclohexane in both 1 and 10 and 2 ratios. The resulting methacrylic acid 2-hydroxyethoxyethyl ester of formula II contained 0/21 wt. diester and 0.128 wt.%, diethylene glycol. All four extraction steps were again performed on a countercurrent extraction column and vibrating trays.

The method of the invention (in contrast to the prior art methods) substantially reduces the formation of di- and oligomers as it significantly reduces the proportion of water in the aqueous phases referred to for the countercurrent contact with the β alkane and and oxygenated organic solvent. inhibitor. The introduction of a countercurrent contact of the alkane extract with water without significant product losses and allows a perfect separation of the product from the die / methanol and methacrylic acid matyl ether. The total water consumption and the energy required for its evaporation are substantially reduced by the method according to the invention. Finally, by reducing the water content of the aqueous phase brought into countercurrent contact with an ethereal or higher ketone-type oxygen solvent, a sharper separation of glycol and other impurities from the product can be achieved with minimal losses.

Claims (1)

OBJECT OF THE INVENTION Process for the continuous refining of a methacrylic acid monoester and ethylene glycol or diethylene glycol (in which a crude product from reesterification / crude monoeeter) is introduced into an intense countercurrent ethylene vibration using an alkane or cyclo-solvent 4 CS 273760 B1 of alkanes and then the monoeater extracts from the aqueous phase by vigorous countercurrent contact with vibration and an acidic organic solvent sparingly soluble in water / wherein the olefin-type solvent comprises hydrocarbons having 6 to 10 carbons β oxygen characterized in that 50 to 150 ppm of a phenol-type inhibitor, preferably p-methoxyphenol, are added to the crude monooster containing at least 30% by weight of the mono-motor, and (a) slurry, ¹ cycloalkane, or mixtures thereof. after intensive countercurrent contact with the crude monoeeterene, Yet it is in intensive countercurrent contact with water containing! 50 to 150 ppm of inhibitor in the ratio of water to organic phase flow rates of 1 to 4 to 1 to 4 / preferably 1 to 1.0 to 1 to 2.0, and then combining this aqueous phase with a crude monoester / aqueous the phase after contacting the crude monoester with an alkene or cycloalkane type solvent is re-enriched with an inhibitor to a concentration of 60 to ISO ppm / whereafter and introduces the known countercurrent contact with an ether or ketone type solvent.