Preparation of N-acylaminocarboxylic acids and N-acylaminosulfon

Details Preparation of N-acylaminocarboxylic acids and N-acylaminosulfon Preparation of N-acylaminocarboxylic acids and N-acylaminosulfon

1998-01-13

1999-04-27

Richter, Johann

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

Organic compounds

Sulfonic acids or salts thereof

562524, 562525, C07C 5116, C07C 51097

Patent

active

058980849

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to an improved process for preparing N-acylaminocarboxylic acids and N-acylaminosulfonic acids and their alkali metal salts from the alkali metal salts of, respectively, aminocarboxylic acids and aminosulfonic acids and certain carboxylic esters.
WO-A 95/07881 discloses that alkali metal salts of N-acylsarcosine can be prepared by acylating an alkali metal sarcosinate with alkyl carboxylates, in particular methyl carboxylates, in the presence of basic catalysts such as sodium methoxide or potassium ethoxide at from 80 to 200.degree. C. The disadvantage of this method is the use of alkyl carboxylates, for example methyl oleate, which has to be expensively prepared in an upstream synthesis step and may have to be purified.
It is an object of the present invention to provide an efficient and economical process for preparing N-acylaminocarboxylic acids and N-acylaminosulfonic acids and alkali metal salts thereof in sufficient purity in good space-time yields starting from readily obtainable and inexpensive starting materials.
We have found that this object is achieved by a process for preparing an N-acylaminocarboxylic or N-acylaminosulfonic acid or an alkali metal salt thereof from an alkali metal aminocarboxylate or aminosulfonate and a carboxylic ester by aminocarboxylate or aminosulfonate in the carboxylic ester, N-acylaminocarboxylate or N-acylaminosulfonate, and N-acylaminosulfonic acid therefrom in a conventional manner by adding an acid,
Step (a) is carried out, for example, by introducing the carboxylic glyceride and the solid anhydrous alkali metal aminocarboxylate or aminosulfonate into a suitable vessel made of glass or some other material and processing the contents with a customary suspending stirrer into a finely divided suspension.
The suspension of step (a) can also be prepared by mixing the carboxylic glyceride and an aqueous solution of the alkali metal aminocarboxylate or aminosulfonate in a suitable vessel made of glass or some other material and then, by heating and applying a vacuum, removing the water from the mixture as rapidly as possible. Surprisingly, there is very little saponification of the carboxylic glyceride to the alkali metal salt of the underlying carboxylic acid. The advantage of using such an aqueous solution is that industrially produced aqueous solutions of alkali metal aminocarboxylates or aminosulfonates can be used without further preparation such as spray drying. Nor are there any problems associated with the handling of solids, such as dusting or uniform metering.
Typically, the suspension of step (a) is prepared from equivalent or substantially equivalent amounts of the alkali metal aminocarboxylate or aminosulfonate, based on the acyl groups in the carboxylic glyceride, and of the carboxylic glyceride; that is, typically in a molar ratio of 3:1 (in the case of pure triglycerides). An excess of carboxylic glyceride, for example as diluent, is normally not necessary. In some cases, it can be advantageous to have an excess of alkali metal aminocarboxylate or aminosulfonate, for example up to a molar ratio of 5:1.
In step (b), the suspension prepared in step (a) is admixed with a strong base in a catalytic, equimolar or greater amount to initiate the reaction. The base is usually added after or during the heating-up of the suspension to the reaction temperature, but may also be added even in the course of the preparation of the suspension in step (a), for example together with the alkali metal aminocarboxylate or aminosulfonate, or shortly before the suspension is heated up. The base can be used as a solid substance or in dissolved form, for example in an organic solvent such as an alcohol.
The amount of strong base used is preferably from 0.5 to 150 mol %, in particular from 1 to 50 mol % or from 50 to 130 mol %, preferably from 5 to 20 mol % or from 70 to 110 mol %, based on the alkali metal aminocarboxylate or aminosulfonate. Depending on the specific conditions of the reaction, it can be better to use the strong base in a catalytic o

REFERENCES:
patent: 4380646 (1983-04-01), Franzmann

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