Mechanistic Inferences in the Reaction of Metal Ethoxyacetylacetonates with Ozone: A Matrix Isolation Study

• First observation of peracetic acid formed from the reaction of O 3 with Cu(ethac) 2 . • Verification of the Criegee mechanism for the reaction of O 3 with Cu(ethac) 2 . • First observation of secondary reaction products from peracetic acid. • Development of a partial reaction mechanism of a gas-solid reaction. • Demonstration of the effectiveness of flow-over deposition. The reaction of O 3 with copper ethoxyaceylacetonate, Cu(ethac) 2 , and its nickel counterpart is reported using matrix isolation, infrared spectroscopy and theoretical calculations to identify key reaction products and make inferences as to the reaction mechanism. The newly reported flow-over deposition method for matrix isolation was used to initiate the chemical reactions reported here. Oxygen isotopic labeling with 18 O was used to help confirm product identities. The primary observed reaction products are peracetic acid, ethyl glyoxylate and monoethyl oxalate, including two rotamers each of the latter two products. Some further reaction of peracetic acid was noted as well, forming CO 2 , CH 2 O and likely CH 4 . The reaction appears to occur through the initial formation of a metal-bound primary ozonide that decomposes to form peracetic acid and ethyl glyoxylate, with the latter compound then oxidizing further to monoethyl oxalate.