Mercapto compound, a high refractive index resin and lens and a process for preparing them

A process for preparing the mercapto compound of the formula (I) ##STR24## comprising reacting thiourea and a triol compound of the formula (II) ##STR25## in the presence of a mineral acid to form a reaction mixture, and adding a base to hydrolyze the reaction mixture to form the mercapto compound.

A process for preparing the mercapto compound of the formula (I) ##STR26## comprising reacting thiourea and a triol compound of the formula (III) ##STR27## in the presence of a mineral acid to form a reaction mixture, and adding a base to hydrolyze the reaction mixture to form the mercapto compound.

A process for preparing the mercapto compound of formula (I) ##STR28## comprising obtaining the triol compound of formula (II) ##STR29## by reacting epihalohydrin with 2-mercapto ethanol in the presence of a base, reacting the triol compound with thiourea in the presence of a mineral acid to form a reaction mixture, and adding a base to hydrolyze the reaction mixture to form the mercapto compound.

A process for preparing the mercapto compound of the formula (I) ##STR30## comprising obtaining a mixture of triol compounds of the formula (II) and (III) ##STR31## by reacting 2,3-dihalogeno-1-propanol with 2-mercaptoethanol in the presence of a base, reacting the mixture with thiourea in the presence of a mineral acid to form a reaction mixture, and adding a base to hydrolyze the reaction mixture to form the mercapto compound.