Preparation of the calcium salt of .alpha.-hydroxy-gamma-methylmercaptobutyric acid

• US 4,310,690 A
• Filed: 10/08/1980
• Issued: 01/12/1982
• Est. Priority Date: 10/08/1980
• Status: Expired due to Term

• Current Assignee: Novus International, Inc. (Nippon Soda Company Limited)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Cummins, Earl W.
• Primary Examiner(s): Killos, Paul J.
• Application Number:
  US06/195,082
• Time in Patent Office: 461 Days
• Field of Search: 562/581
• US Class Current: 562/581
• CPC Class Codes: C07C 323/00 Thiols, sulfides, hydropolysulfides or polysulfides substituted by halogen, oxygen or nitrogen atoms, or by sulfur atoms not being part of thio groups

Abstract

This invention relates to a novel process for preparing the calcium salt of α-hydroxy-γ-methylmercaptobutyric acid (MHBA).

Claims

1. A process for preparing the calcium salt of α

-hydroxy-γ

-methylmercaptobutyric acid (MHBA) which comprises;

(a) contacting a reaction mixture obtained by hydrochloric acid hydrolysis of α

-hydroxy-γ

-methylmercapto butyronitrile to MHBA with aqueous sodium hydroxide, recycled wash liquor from step (f) and water to form a solution having a pH in the range of about 6.0 to 8.0;

the quantity of sodium hydroxide, recycled wash and water being controlled so as to provide a filtrate in step (d) with a sodium chloride content of about 18 to 22%;

(b) mixing into the solution formed in step (a) a quantity of aqueous lime slurry prepared using recycled wash liquor from step (f), said quantity being sufficient to form a reaction mixture having a pH of about 8.5 to 11.0 at about 45°

to 90°

C.;

(c) filtering the reaction mixture to recover the product calcium salt and to yield a filtrate having a sodium chloride content of about 18 to 22% by weight;

(d) washing the product calcium salt with water; and

(e) retaining a portion of the wash liquor for recycling to the reaction mixture in step (a) and preparing the aqueous lime slurry used in step (b).

2. The process of claim 1 wherein the solution formed in step (a) has a pH in the range of about 6.5 to 7.0.

3. The process of claim 1 wherein the temperature of the reaction mixture in step (b) is maintained at about 50°

to 60°

C.

4. The process of claim 1 wherein the pH of the reaction mixture in step (b) is about 9.0 ;

l to 9.5.

5. The process of claim 1 wherein the product calcium salt is dried to reduce water content to at least about 1% by weight.