G. Hizal et al., ON THE PHOTOLYSIS OF PHTHALIC-ACID DIALKYL ESTERS - A PRODUCT ANALYSIS STUDY, Journal of photochemistry and photobiology. A, Chemistry, 72(2), 1993, pp. 147-152
The following phthalic acid dialkyl esters were subjected to UV irradi
ation (lambda(inc) = 254 nm at 22-degrees-C or lambda(inc) = 240-440 n
m at 40-degrees-C): phthalic acid di(2-ethylhexyl) ester (DOP), phthal
ic acid di(n-octyl) ester (DNOP), phthalic acid di(n-decyl) ester (DDP
) and phthalic acid dimethyl ester (DMP). In all cases (except DMP) an
alogous major photoproducts identified by the gas chromatography-mass
spectrometry (GC-MS) method are formed: 1-alkenes, alkyl alcohols, pht
halic acid anhydride, 2-formyl benzoic acid esters and benzoic acid es
ters. Generally, the quantum yields of decomposition are quite low: ph
i less-than-or-equal-to 0.03. Extension of the linear alcohol chains d
ecreases the stability: phi(-DMP)<phi(-DNOP)<phi(-DDP). In the absence
of O2, DOP, which contains branches in the alcohol chains, is more st
able than the isomeric DNOP containing linear alcohol chains: phi(-DOP
)< phi(-DNOP).