Evidence for the HOOO(-) anion in the ozonation of 1,3-dioxolanes: hemiortho esters as the primary products.
Low-temperature ozonation (-78 degrees C) of 2-methyl-1,3-dioxolane (1a) in acetone-d6, methyl acetate, and tert-butyl methyl ether produced both the corresponding acetal hydrotrioxide (3a, ROOOH) and the hemiortho ester (2a, ROH) in molar ratio 1:5. Both intermediates were fully characterized by 1H, 13C, and 17O NMR spectroscopy, and they both decomposed to the corresponding hydroxy ester at higher temperatures. The mechanism involving the HOOO- anion formed by the abstraction of the hydride ion by ozone to form an ion pair, R+ -OOOH, with its subsequent collapse to either the corresponding hemiortho ester (ROH) or the acetal hydrotrioxide (ROOOH) was proposed. This mechanism is supported by the PISA/B3LYP/6-311++G(3df,3pd) calculations.
Plesnicar
Bozo
B
Department of Chemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, P.O. Box 537, 1000 Ljubljana, Slovenia. bozo.plesnicar@uni-lj.si
Cerkovnik
Janez
J
Tuttle
Tell
T
Kraka
Elfi
E
Cremer
Dieter
D
D000838:Anions; D003080:Cold Temperature; D004148:Dioxolanes / Q000737:chemistry*; D004952:Esters / Q000737:chemistry; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D010087:Oxides / Q000737:chemistry*; D010126:Ozone / Q000737:chemistry*
D000838:Anions; D004148:Dioxolanes; D004952:Esters; D010087:Oxides; D010126:Ozone