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Method for producing alpha-hydroxycarboxylic acid esters

A technology of hydroxycarboxylate and hydroxycarboxamide, applied in the field of preparation of α-hydroxycarboxylate, can solve the problems of no conversion, uninteresting procedures, etc., achieve high conversion rate, low tendency to form by-products, The effect of long service life

Inactive Publication Date: 2014-03-26
EVONIK ROEHM GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0013] It is almost always necessary to remove ammonia using an inert gas and the additional treatment of another stream associated with this (stripping gas / ammonia separation) makes the proposed procedure less economically interesting, making the method hitherto not industrially transformed

Method used

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Examples

Experimental program
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Effect test

Embodiment 1

[0080] In a continuously operated laboratory consisting of a reactant metering system, a trickle bed reactor designed as a random packing tower (ID100mm, L1000mm, Interpack10mm random packing) with liquid circulation and vapor phase discharge, and a product condensation system In the test plant, vaporous methanol and α-hydroxyisobutyramide fed in as a melt were converted within 48 h by means of a catalyst soluble in the liquid phase. The catalyst used was La(NO 3 )x6H 2 O. The temperature of the liquid circuit is 180° C.; the pressure in the reactor is adjusted to 800 mbar. The vapor phase was condensed completely and continuously and the composition was determined by gas chromatography and titration. The selectivity to methyl α-hydroxyisobutyrate, based on methanol, was 99.8%; the ammonia concentration in the condensate was 4.8% by weight. The average methanol conversion over the time of the experiment was 12%.

Embodiment 2

[0084] Improve the trickle bed reactor used in embodiment 1, make use based on ZrO 2 (3 mm pellets) in heterogeneous contacts as catalysts instead of random packings. During a period of 48 h, vaporous methanol and α-hydroxyisobutyramide supplied as a melt were reacted. The temperature of the liquid circuit is 170° C.; the pressure in the reactor is adjusted to 800 mbar. The vapor phase was condensed completely and continuously, and the composition was determined by gas chromatography and titration. The selectivity to methyl α-hydroxyisobutyrate, based on methanol, was 99.85%; the ammonia concentration in the condensate was 4.83% by weight. The average conversion of methanol was 13%.

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Abstract

The invention relates to a continuous method for producing alpha-hydroxycarboxylic acid esters, at least one alpha-hydroxycarboxylic acid amide, which is present in the liquid phase, being reacted with an alcohol in the presence of a catalyst. The method is characterized in that the obtained alpha-hydroxycarboxylic acid esters are at least partially removed from the reaction mixture by means of the gas phase.

Description

technical field [0001] The present invention relates to the preparation method of α-hydroxy carboxylate. Background technique [0002] α-Hydroxycarboxylates are valuable intermediates in the industrial-scale synthesis of acrylates and methacrylates (hereinafter referred to as alkyl (meth)acrylates). Alkyl (meth)acrylates are used in large quantities in the preparation of polymers, such as polymethylmethacrylate. [0003] An overview of common methods for preparing (meth)acrylates can be found in the literature, for example Weissermel, Arpe, "Industrielle organische Chemie" [Organic Chemistry Industry], VCH, Weinheim 1994, 4th edition, p. 305 et seq., or Kirk Othmer , "Encyclopedia of Chemical Technology", 3rd Edition, Vol. 15, p. 357. [0004] If the aim is the synthesis of methacrylates, such as methyl methacrylate, as an α-hydroxycarboxylate, methyl 2-hydroxyisobutyrate (=MHIB) is an important intermediate for their preparation. [0005] The preparation of [alpha]-hydro...

Claims

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Application Information

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IPC IPC(8): C07C67/20C07C67/54C07C69/675
CPCC07C51/06C07C67/20C07C69/675
Inventor M·克斯特纳W·普洛赛A·梅
Owner EVONIK ROEHM GMBH
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