ethyl cysteine hydrochloride synthesis

Yield:75521-14-1 87.5%

Reaction Conditions:

Stage #1: ethanolwith thionyl chloride at -5 - 20; for 1.5 h;
Stage #2: D-cysteine at 50; for 4 h;

Steps:

1.1 (1) Synthesis of D-cysteine ethyl ester hydrochloride

120 mL (2.087 mol) of absolute ethanol was added to a 250 mL three-necked flask with a drying tube,Magnetic stirring,In the low temperature constant temperature water bath cooling -10 below.8.7 mL (0.11 mol) of thionyl chloride was slowly added dropwise to a three-necked flask using a constant pressure dropping funnel,The reaction temperature was maintained below -5 ° C during the dropwise addition.After the drop of low temperature reaction 1h,Natural recovery to room temperature reaction 0.5h.The reaction solution was transferred to a 250 mL single-necked flask,12.10 g (0.1 mol) of D-cysteine was added,Stirring to completely dissolved and heated to 50 ° C for 4 h.During TLC monitoring to termination of the reaction,The product is steamed,Removing the solvent,The remaining white crude product is solid.Recrystallization from absolute ethanol,Filter,Vacuum drying to constant weight,To obtain D-cysteine ethyl ester hydrochloride,The yield was 87.5%.

References:

CN106380417,2017,A Location in patent:Paragraph 0047; 0048