Chloroacetic Acid → S-(Carboxymethyl)cysteine

As starting material there served (RS)-cysteine hydrochloride which was produced by the process of German OS No. 2645748. 140 grams (1 mole) of this material together with 160 grams (4 moles) of sodium hydroxide were dissolved in 1000 ml of water. To this solution there was first added 3 grams of sodium hydrogen sulfide and then in the course of 45 minutes 95 grams (1 mole) of monochloroacetic acid. The temperature of the mixture in the meanwhile was held at 20° C. and after that held for 3 hours at 20° to 30° C. The reaction mixture was subsequently adjusted to a pH of 3.0 by addition of concentrated, aqueous hydrochloric acid. Hereby the S-(carboxymethyl)-(RS)-cysteine separated out. It was filtered off at 10° C. and washed with water until it was free from chloride ions. Then it was dried under reduced pressure at 105° C. The yield was 173 grams, corresponding to 97% based on the cysteine hydrochloride employed. The melting point (decomposition point) of the S-(carboxymethyl)-(RS)-cysteine was 188° to 192° C.

1. customwas produced by the process of German OS No
2. customwas held at 20° C.
3. additionThe reaction mixture was subsequently adjusted to a pH of 3.0 by addition
4. concentrationof concentrated
5. customHereby the S-(carboxymethyl)-(RS)-cysteine separated out
6. filtrationIt was filtered off at 10° C.
7. washwashed with water until it
8. customThen it was dried under reduced pressure at 105° C
9. customwas 188° to 192° C.

ORD record

ord-2f53965f661d458cb6c87d80856a64e7

Source dataset

uspto-grants-1983_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04411840