Abstract: The active intermediates produced in the photolysis of dialkyl phosphites (RO)₂P(0)H (R=C₂H₅, n-C₃H₇, i-C₃H₇, n-C₄H₉) and their mercury derivatives (RO)₂P(0)HgX(X=OAc, Cl, Br)were studied by spin trapping and ESR spectro-scopy. The results showed that radicals (RO)₂ P(0) were formed from the above two types of compounds during UV irradiation, and could be trapped by PBN. From the fact that the homolysis of P-Hg bond is much easier than that of P-H bond, the bonding characteristics of P-Hg bond in the mercury compounds is discussed.

Key words: Dialkyl phosphites, Mercury derivatives, Photolysis, Spin trapping, ESR