Process for preparing alkaline earth metal mercaptides

Claim 1

A process for preparing alkaline earth metal mercaptides of the general formula M(SR) 2 , wherein M is selected from the group consisting of barium, strontium, and calcium and R is a hydrocarbon radical having from 1 to 22 carbon atoms and is selected from the group consisting of alkyl, cycloalkyl, aryl and mixed alkyl-aryl, said hydrocarbon radicals can optionally have a noninterfering substituent selected from the group consisting of halogen, --XH, --XR 2 , ##STR3## where R 2 is a hydrocarbon radical having from 1-20 carbon atoms and is selected from the group consisting of alkyl, alkenyl, cycloalkyl, aryl and mixed alkylaryl with the proviso that R 2 may be further substituted with inert substituents and X and Y are independently selected from the group consisting of oxygen and sulfur, comprising: (1) forming a reaction mixture of: (a) a metal alkoxide of the general formula M 1 (OR 1 ) x , wherein M 1 is selected from the group consisting of magnesium, aluminum or calcium with the proviso that when M 1 is calcium M is barium or strontium; R 1 is a hydrocarbon radical having from 1-20 carbon atoms and selected from the group consisting of alkyl, cycloalkyl, or aralkyl with the proviso that the hydrocarbon radical can be substituted with inert or noninterfering substituents: and x is a number equal to the valence of M 1 : and (b) a metal oxide or hydroxide of the formula MO, or M(OH) 2 , wherein M is selected from the group consisting of barium, strontium or calcium; and (c) an alcohol of the general formula R 1 OH wherein R 1 is as above defined: (2) subjecting the reaction mixture of (1) to reaction conditions that include heating the mixture for sufficient time to provide M 1 (OH) x and a metal alkoxide of the general formula M(OR 1 ) 2 ; (3) forming a reaction mixture of: (a) the metal alkoxide M(OR 1 ) 2 of step (2), and (b) a mercaptan of the general formula RSH, wherein R is as above defined; (4) subjecting the mixture of (3) to reaction conditions to provide the alkaline earth metal mercaptide of the general formula M(SR) 2 ; and then (5) separating the metal mercaptide M(SR) 2 from the mixture of step (4).