Oblon, Fisher, Spivak, McClelland & Maier
Process for producing L-cysteine or its derivatives
 L-cysteine and derivatives thereof of the formula (I): ##EQU1## wherein R is selected from the group consisting of hydrogen, C.sub.1 -C.sub.15 alkyl, C.sub.2 -C.sub.15 alkenyl, C.sub.6 -C.sub.15 aryl, C.sub.7 -C.sub.15 aralkyl, are prepared by a process which comprises reacting .beta.-substituted L-alanine having the formula (II): ##EQU2## wherein X is selected from the group consisting of halogen, --OR' and --SR'; wherein R' is selected from the group consisting of hydrogen, allyl, C.sub.1 -C.sub.15 alkyl, C.sub.6 -C.sub.15 aryl and C.sub.7 -C.sub.15 aralkyl, with a thiol, or hydrogen sulfide, of the formula (III): EQU r -- sh (iii) wherein R is as defined above, ammonium hydrosulfide of a metal hydrosulfide of the formula (IV): EQU r -- s --y (iv) wherein R is hydrogen, and Y is ammonium or a metal, in an aqueous medium, in the presence of cysteine desulfhydrase. 
Mitsubishi Chemical Industries Ltd.
Y Y Y C Y Y Y Y Y C Y Y C Y Y Y
Y10S Y10S Y10S C12P Y10S Y10S Y10S Y10S Y10S C12P Y10S Y10S C12N Y10S Y10S Y10S
additional additional additional inventional additional additional additional additional additional inventional additional additional inventional additional additional additional
Haruyiki Hideaki Hidehiko
Ohkishi Yamada Kumagai