Study On The Multicomponent Solid-liquid Equilibrium Of L-Cysteine And Its Derivatives In Solvent Systems

L-Cysteine and its derivatives are widely used in many fields such as medicine and food as important synthetic intermediates.In order to optimize its industrial production process,the study of solid-liquid phase equilibrium of L-cysteine and its derivatives in different solvent systems is very important.The solubility data is the key to studying the solid-liquid phase equilibrium process of substances.There are only two reports on the solubility data of L-cysteine and the system involved is single.However,there are no reports on the solubility data of L-cysteine methyl ester hydrochloride and DL-homocysteine thiolactone hydrochloride.The existing data cannot optimize the industrial production process of L-cysteine and its derivatives,nor is it sufficient to design its crystallization process.Therefore,this article aims to systematically determine the solubility of L-cysteine and its derivatives in different pure solvents and binary mixed solvents.Under the atmospheric pressure,L-Cysteine solubility in twelve monosolvents(water,methanol,ethanol,n-propanol,n-butanol,sec-butanol,isopropanol,isobutanol,ethyl acetate,1,4-dioxane,acetonitrile,and acetone)and three binary solvents(water+methanol,water+ethanol,and water+isopropanol)were determined by the gravimetric method from 283.15 to 323.15 K;L-Cysteine methyl ester hydrochloride solubility in fourteen monosolvents(methanol,ethanol,n-propanol,n-butanol,sec-butanol,isopropanol,isobutanol,ethyl acetate,1,4-dioxane,acetonitrile,acetone,2-butanone,n-pentanol and dichloromethane)were determined by the static gravimetric method from 283.15 to 333.15 K;DL-homocysteine thiolactone hydrochloride solubility in nine neat solvents(methanol,ethanol,isopropanol,ethyl acetate,1,4-dioxane,acetonitrile,acetone,2-butanone and dichloromethane)were determined by the static gravimetric method at the atmospheric pressure from 283.15 to 323.15 KThe solubility data of L-cysteine and its derivatives were fitted by modified Apelblat model,yaws model,jouyban Acree model,machatha model,Apelblat jouyban Acree model and Apelblat machatha model respectively,and the fitting results were good,indicating that these models can be used to predict the solubility of L-cysteine and its derivatives.This paper can provide basic solid-liquid equilibrium data for the industrial production and crystallization purification of L-cysteine and its derivatives.