Abstract Phosphonochloridous and phosphonous esters were prepared from the reaction of phenylphosphonous dichloride with 2, 4-di-tert-butylphenol, 2, 6-di-tert-butyl-4- methylphenol, and 2, 4, 6-tri-tert-butylphenol. Various synthetic methodologies, including phase-transfer catalysis, are described and compared. Phosphonous diesters containing two different substituted-phenyl moieties were prepared from phosphonochloridous ...