239127-35-6Relevant articles and documents
Photosensitized oxygenation of benzyl ethyl sulfide
Bonesi,Mella,D'Alessandro,Aloisi,Vanossi,Albinit
, p. 9946 - 9955 (1998)
Singlet oxygen adds to benzyl ethyl sulfide (5, total quenching rate ca. 1 x 107 M-1 s-1, little dependent on the solvent) to ultimately give benzaldehyde (6) and a small amount of the sulfone (8) in aprotic media (rate of the chemical reaction in benzene 5.5 x 106 M-1 s-1) and mainly the sulfoxide (7) in protic media (1.1 x 107 M-1 s-1 in methanol). In the presence of small amounts (0.002-0.3 M) of protic additives (alcohols, phenol, carboxylic acids), the sulfoxide becomes the main product in benzene also. Various evidence support the formation of two intermediates in aprotic solvents. The first one is an exciplex or a syn persulfoxide. It undergoes intramolecular hydrogen abstraction to give a ylide and finally benzaldehyde. Such rearrangement is either a concerted or a radicalic process and not a proton transfer (as indicated by the deuterium effect observed with the α-d benzyl sulfide and the occurrence of the process with the p-nitro and p- methoxy derivatives, 5' and 5''). This intermediate is not quenched except under relatively strong acidic conditions. A second intermediate, arising either from the first one or through a parallel path, has the properties usually associated with the persulfoxide (possibly it is the anti rotamer). This species gives some sulfoxide but mainly decays to the unreacted sulfide; it can be trapped intermolecularly, however, both by acids and by diphenyl sulfoxide (in the latter case it gives more of sulfone 8 than of sulfoxide 7). The relative rates of protonation of both the first and the second intermediate (determined in benzene doped with protic additives) correlate with the gas-phase acidity of such additives. As for the reaction in neat alcohols and in benzene doped with acids, a single intermediate intervenes. This is better described as a S-hydroperoxy cation rather than a neutral hydroperoxysulfurane and is trapped by both diphenyl sulfoxide and sulfone at rates close to those measured for the photo-oxidation of diethyl sulfide.
