2.3- Dimethyl-2-hydroperoxy-3-butene

As yet we have not been able to isolate the presumed intermediates. Low temperature, extraneous radical-induced decompositions of 2,3 dimethyl-2-hydroperoxy-3-butene (TMEH) (16) gave some addition, and epoxide formation, when the radical was CHa. With Ph3C, however, the only induced product was PhaCOH from Sjj2 displacement. Clearly the propensities for alkyl radicals to attack at the several available sites require elaboration. 

A soln. of 2,3-dimethyl-2-butene in methanol treated with SO -HgOg, then a ca. M NaOGl-soln. added during 1.5 hrs. 2,3-dimethyl-3-hydroperoxy-l-butene. Y 63%.—The oxidations proceed very smoothly and the products are identical with those of dye-photosensitized autoxidations (s. Synth. Meth. 14, 172). F. e. s. G. S. Foote and S. Wexler, Am. Soc. 86, 3879 (1964). 

The allylic hydroperoxide, 2,3-dimethyl-3-hydroperoxy-l-butene, III, was detected during the oxidation of TME in the presence of [MCl(CO)-(Ph3P)2] (M = Rh, Ir) and reached a maximum yield of 11% after 3.5 hours when the rhodium complex was used (Figure 1). James and Ochiai (13) have cited spectral evidence for hydroperoxide intermediates, and Fusi et ah (14) obtained evidence which supports the intermediacy of an allylic hydroperoxide during cyclohexene oxidation in the presence of metal complexes. The allylic hydroperoxide (III) which is formed during the oxidation of TME in the presence of [MCl(CO) (Ph3P)2]... 

Figure 26. (a) UV-Vis transmittance spectra of 02-N2/NaY (1) and DMB/02-N2/NaY (2) for films of large Na-Y crystals at 253 K. Bars indicate the estimated DMB-O2 absorption for scattered and unscattered transmitted light, (b) Proposed mechanism for the formation of 2,3-dimethyl-3-hydroperoxy-l-butene in DMB/02-NaY. 

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