Matrix isolation study of the reaction of O (3P) with 1,3 butadiene: Unexpected formation of ethylketene

The light-induced reaction of ozone with 1,3-butadiene in argon matrixes is described, using either red (625 nm) or UV (254 nm) irradiation. Products were observed using infrared spectroscopy and identification was aided by O-18 and deuterium experiments. The experimental work was supported by extensive OFT calculations. Four products were anticipated to be formed, ethenyloxirane, 2-butenal, 3-butenal and 2,5-dihydrofuran, and all four were observed. These results suggested the intermediacy of a triplet biradical H2C=CH-CH-CH2O formed through the initial step of the reaction of (OP)-P-3 with butadiene. In addition, one unexpected product was conclusively identified, ethylketene, formed through a double hydrogen shift after formation of the initial triplet biradical. Some product variation was observed with the different wavelengths of irradiation, reflecting the spin multiplicity of the initially formed O atom. (C) 2018 Elsevier B.V. All rights reserved.