Infrared spectroscopy ozonides

The double )5-scission pathway becomes dominant in bicyclic systems (Equations (7)-(9) and Scheme 13). Thus, cyclopentene ozonide (69) gives cyclopropane (Equation (7)) <68TL329l>. Photolysis of the ozonide derived from 1,4-benzodioxins (70) provides a method for the preparation of labile o-benzoquinones (71) (Scheme 13) <87JOC56l6>. Photolysis can also provide a route to unstable compounds and transient species such as the aziridine-2,3-dione (72) (Equation (8)), identified at 77 K using infrared spectroscopy <80JA6902>. Relatively unstable azacarbapenems (73) have been prepared by photolysis of tricyclic compounds containing a cyclobutene ozonide (Equation (9)). On silica, the 1,2,4-trithiolane (74) underwent photo-equilibration (Equation (10)) with the 1,3-dithetane (75) and sulfur. 

Niki etal. (1977) have identified this product by long-path infrared spectroscopy in a study of the gas phase ozonolysis of ci s-2-butene. The occurrence of secondary ozonides in the gas-phase corresponds entirely to their production in the liquid phase at low temperatures (Criegee, 1957). These results led Dodge and Arnts (1979) to derive from a computer simulation of the experimental data of Niki et al. (1977) the following percentages... 

By use of matrix isolation infrared spectroscopy, it has been shown that the mechanism of ozonolysis of (Z)-3-methyl-2-pentene (mp) is similar to that for ozonolysis of simple alkenes. Indirect evidence for formation of one or both possible Criegee intermediates is presented. Eight fundamental vibrations of the c/s -isomer of the primary ozonide of mp are observed. UV irradiation led to the product arising from O atom addition to mp. Second-order rate coefficients for the ozonolysis of -butyl methacrylate, ethyl cro-tonate and vinyl propionate under atmospheric pressure have been determined and the effects of substituent groups on the overall rate coefficients have been analysed. Free energy relationships are presented and atmospheric lifetimes are discussed. ... 

A further aspect of the investigations was the analysis results obtained with offline HPLC analysis were compared with results of online FTIR-ATR spectroscopy. It showed that the mid-infrared-ATR spectroscopy is a suitable tool for online detection of unstable or explosive intermediates such as ozonides and/or hydroperoxides and that both analysis methods delivered well correlating results. 

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