Dioxetans Subject

The recently discovered preparative methods for the synthesis of 1.2-dioxetane derivatives (see Section V.) have made these compounds and their chemiluminescent decomposition the subject of especially intensive study. 

A further cycloaddition of interest is that of aldehydes and ketones to furans.289 The oxetane and dioxetanes formed from furan and benzophenone have been the subject of considerable study, and are now believed290 to have the detailed structure and stereochemistry... 

Dioxetanes and dioxetanones behave chromatographically the same as any organic derivative and as such their Rf will be dependent on the polarity of the substrate as a whole. No special precautions are necessary during chromatography except that one may need to guard against thermal instability. Solubilities will also be subject to... 

Dioxetanes have been the sole subject of several specialized reviews in recent years (Bartlett and Landis, 1979 Horn et al., 1978-79 Adam, 1977 T. Wilson, 1976 Turro et al., 1974a Mumford, 1975). These articles cover with depth which is not possible here such topics as (1) preparation, (2) physical and spectroscopic characterization, (3) experimental techniques, especially for the study of chemiluminescence, (4) mechanisms of decomposition and chemiexcitation, (5) ground state transformations, and (6) reactions involving dioxetanes as postulated intermediates. The interested reader is referred to these articles for details on these specialized topics, and for some interesting historical perspectives. 

As additional support for the diradical mechanism, it was shown that the 3,4-diethoxy-l,2-dioxetane (8) and the p-dioxene-l,2-dioxetane had identical activation energies, implying that the C-C bond is not significantly stretched in the activated complex. That these notions on substituent effects in dioxetane decomposition are grossly oversimplified has come clearly into focus in recent years (Table 4). The fact that little yet is understood about the correspondence between activation parameters and dioxetane structure has already been amply expounded in Section V.l.B. Nevertheless, a few additional comments seem appropriate on this subject in... 

Chemiluminescence.—The triplet potential-energy surface of dioxetan has been found to intersect the singlet surface between dioxetan and the transition state for dioxetan decomposition to formaldehyde. This provides support for the argument that the reason for efficient triplet ketone formation on thermolysis of dioxetans is because intersystem crossing is an integral part of the reaction.293 The decomposition mechanism of 1,2-dioxetans has been the subject of another theoretical investigation.294 ... 

Recent efforts to report and to repair mechanical damage with mechanochemical reactions form the subject of the current chapter. We start with a brief discussion of the use of the spiropyran unit as a mechanophore for reporting strain. Spiropyran mechanochemistry inspired the development of another stress probe, the highly sensitive mechanoluminescent dioxetane, whose application as scission reporter in several types of polymeric materials is discussed. The chapter continues with a description of recent efforts to develop productive mechanochemistry, where initial scission leads to the formation of new bonds. Bond formation is either induced by the scission of covalent bonds, e.g. by the opening of rings, or bonds are formed under the action of a latent catalyst when it is activated by mechanochemical dissociation of a Lewis acid-base pair. These examples of productive mechanochemistry offer exciting possibilities to develop new modes of self-healing in... 

Chemiluminescence and Bioluminescence.—The function of thiazole and benzothiazole derivatives in the processes of bioluminescence and chemiluminescence continues to form the subject of significant investigations. Extensive contributions have been provided by White et al., ° who have reviewed this interesting and active field. They have shown that the luminescence of firefly luciferins involves intermediates having dioxetan structures. 

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