Preparation of N-acylamino carboxylic acids and N-acylamino sulf

Details Preparation of N-acylamino carboxylic acids and N-acylamino sulf Preparation of N-acylamino carboxylic acids and N-acylamino sulf

1997-03-24

1999-01-05

Geist, Gary

Organic compounds -- part of the class 532-570 series

Organic compounds

Fatty compounds having an acid moiety which contains the...

554 49, 562553, 562574, 562575, 562105, C07C23100, C07C20500, C07C22900

Patent

active

058565388

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to an improved process for preparing N-acylamino carboxylic acids and N-acylamino sulfonic acids and their alkali metal salts from the technical alkali metal salts of amino carboxylic acids and amino sulfonic acids, respectively, and from alkyl carboxylates.
2. Discussion of the Background
DE-A 20 04 099 discloses that salts of N-acylamino carboxylic acids can be prepared by acylation of the corresponding amino carboxylic acids or their salts with a carboxylic acid, a carboxylic ester or a carboxamide in the presence of an equivalent amount of a basic compound which forms salts with carboxylic acids, such as an alkali metal or alkaline earth metal hydroxide, at from 100.degree. to 250.degree. C., preferably from 160.degree. to 200.degree. C. In this case the basic compound merely serves to neutralize the amino carboxylic acids or carboxylic acids used. The reaction is carried out in the melt of amino carboxylic acid and acylating agent or in a suspension of the amino carboxylic acid in a solution of an acylating agent and of a basic organic nitrogen compound, eg. an amine, in a high-boiling organic solvent.
However, the disadvantages of the described reaction procedure are the long reaction times and the low yields, which are attributable essentially to the partial decomposition of the starting compounds and of the products because of the high reaction temperatures. This is because the reaction mixture becomes slightly dark in color during this and a slight evolution of carbon dioxide which is almost always observed can likewise be explained only by decomposition reactions.
German Patent Application P 44 08 957.0 describes a process for preparing N-acylamino carboxylic and sulfonic acids from the alkali metal salts of the underlying amino carboxylic and sulfonic acids, respectively, and alkyl carboxylates, in which 0.5 to 30 mol % of strong bases are added as catalyst to a suspension of the amino carboxylic and sulfonic acid salts, respectively, in the carboxylates. However, this process gives satisfactory results only on use of pure alkali metal amino carboxylates or sulfonates with an active content of more than 95% by weight, based on the solids content of the alkali metal salts. Use of corresponding salts of technical quality results in drastic losses of selectivity of up to 15%.


SUMMARY OF THE INVENTION

It is an object of the present invention to provide an efficient and economic preparation process which starts from technical alkali metal amino carboxylates or sulfonates and which gives good space-time yields of N-acylamino carboxylic acids and N-acylamino sulfonic acids or their alkali metal salts in high purities and selectivities.
We have found that this object is achieved by a process for preparing N-acylamino carboxylic acids and N-acylamino sulfonic acids and their alkali metal salts from the technical alkali metal salts of amino carboxylic acids and amino sulfonic acids, respectively, with an active content of 50-95% by weight, preferably 70-94% by weight, in particular 80-93% by weight, based on the solids content of the technical alkali metal salts, and from alkyl carboxylates, which comprises salts of the amino carboxylic acids or amino sulfonic acids in the alkyl carboxylates, the amount required for neutralization to give the alkali metal salts of the N-acylamino carboxylic acids or N-acylamino sulfonic acids, and or N-acylamino sulfonic acids in a conventional way by adding acids.


DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The procedure in step (a) is, for example, for the alkyl carboxylates and the solid anhydrous technical alkali metal salts of the amino carboxylic acids or amino sulfonic acids to be introduced into a suitable vessel of glass or another material and processed with a conventional suspending agitator to give a fine-particle suspension.
However, the suspension can also be prepared in step (a) by mixing together the alkyl carboxylates and an aqueous solution of the technical a

REFERENCES:
patent: 1932180 (1933-10-01), Guenther et al.
patent: 3836551 (1974-09-01), Schroeder et al.
patent: 4233229 (1980-11-01), Chakrabarti

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