ChemicalBook CAS DataBase List L-Cysteine

L-Cysteine synthesis

10synthesis methods

Product Name:L-Cysteine
CAS Number:52-90-4
Molecular formula:C3H7NO2S
Molecular Weight:121.16

L-Cysteine used to be produced almost exclusively by hydrolysis of hair or other keratins. The amino acid isolated was l-cystine, which was reduced electrolytically to l-cysteine. L-Cysteine has also been prepared from beta-chloro-d,l-alanine and sodium sulfide with cysteine desulfhydrase, an enzyme obtained from, e.g., Citrobacterium freundii. Today, however, the main processes for cysteine production are biological. A direct fermentation process has been developed for the manufacture of l-cystine, using a modified Escherichia coli bacterium. The technology has been extended to prepare other modified l-cysteine analogues. An enzymatic process for l-cysteine has been successfully developed using microorganisms capable to hydrolyze 2-amino-delta2-thiazoline 4-carboxylic acid (ATC) which is readily available from methyl alpha-chloroacrylate and thiourea. A mutant of Pseudomonas thiazolinophilum converts d,l-ATC to l-cysteine in 95% molar yield at product concentrations higher than 30 g/L.

52-89-1 Synthesis

52-89-1
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52-90-4
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Yield:52-90-4 92%

Reaction Conditions:

in acetone; for 1.5 h;Heating / reflux;

Steps:

90

L-cysteine hydrochloride monohydrate (100 g, 0.569 mol) was refluxed in dry acetone (1.5 L) under dry nitrogen for 1.5 hours. The white precipitate was collected by filtration and refluxed a second time in dry acetone. Again the white solid was collected to yield 103.6 g of pure product (92 % yield).

References:

WO2007/1926,2007,A2 Location in patent:Page/Page column 257