Process for the preparation of bulky alkyldiarylphosphines and unsymmetrical aryldialkyl phosphines

A process for selectively producing a product phosphine selected from the class consisting of bulky alkyldiarylphosphine of the formula ArAr'PR or unsymmetrical dialkylarylphosphines of the formula R'RP Ar, wherein R represents a bulky alkyl group having from 3 to 20 carbon atoms selected from the group consisting of secondary alkyls, tertiary alkyls, cycloalkyls, bicycloalkyls, and primary alkyls having at least one substituent in the two-position, wherein R' represents a different alkyl group having from 1 to 20 carbon atoms and being less bulky than said R, and wherein Ar and Ar' each represent the same or different aryl group, each having from 4 to 20 carbon atoms, comprising (1) slowly adding about an equimolar amount of a first Grignard reagent of the formula RMgX, where X represents a halogen atom and R is the same as defined above, at a temperature of about -70.degree. C. to about +40.degree. C., to an aryldichlorophosphine of the formula ArPCl.sub.2, where Ar is the same as defined above, and reacting same, to produce a bulky alkylarylchlorophosphine intermediate of the formula ArP(R)Cl, where Ar and R are the same as defined above, and (2) without isolating said intermediate thereafter slowly adding at least about an equimolar amount of a second Grignard reagent of the formula R'MgX, Ar'MgX or Ar'(MgX).sub.2, where Ar', X and R' are the same as defined above to said intermediate and reacting same, to thereby produce the product phosphine.