Catalysis of Organic..

34Halophosphite LigandsThe ligands, 1 - 5 include acyclic and cyclic examples with alkyl and electrondonatinggroups on the aromatic rings. Notably absent from this group are anyligands with electron-withdrawing groups as substituents.ChlorophosphitesEfforts to prepare fluorophosphites with electron withdrawing groups on thephenolic aromatic rings were unsuccessful. The reactions to convert thechlorophosphite intermediates with electron withdrawing groups failed and yieldedonly the unreacted chlorophosphite starting materials. Decomposition of thechlorophosphites did not occur to any significant extent. More forcing conditionswere attempted but the chlorophosphite intermediates were recovered unscathed.The chemical stability of these intermediates with electron withdrawing groups wasunexpected and prompted the question, "Just how stable are these compounds –stable enough to serve as ligands?"Bench unit and autoclave testing of the electron withdrawing substitutedchlorophosphite ligands demonstrated that these intermediate compounds can serveas viable hydroformylation ligands (11). Compounds 6 – 10 are representative ofthe types of chlorophosphite compounds that can be used successfully ashydroformylation ligands. Compound 10 is particularly stable and operates verywell in heavy ester solvents such as bis-2-ethylhexyl phthalate.CF 3 OPOCF 3OPOClCl6Cl7ClMeO8OPOClClOMeClClOOClO9POClOOClOOClPCl10Effect of Reaction Parameters on Catalyst PerformanceThe molar ratio of the phosphorus ligand to rhodium has pronounced effects oncatalyst activity and selectivity. It is well established that increasing the molar ratioof the ligand to the rhodium leads to a higher linear to branched isomer ratio at the