Abstract:
Ozonolysis of tetramethoxyethene 1 produces 20-40% of dimthyl carbonate 3, 35-60% of methyltrimethoxyacetate 7, and
20-35% of the dioxetane 8 of 1. Yield vary with initial concentration of 1, temperature, and solvent. Singlet oxygen is
produced, which reacts with 1 to form 8 and can be trapped with
2,5-dimethylfuran. No evidence for the formation of the molozonide of 1 was obtained. Up to 2.5 moles of 1 are cosumed
per mole of ozone. Ozonolysis of a mixture of 1 and 2,3-dimethyl-2-butene 12 gave the epoxide of 12 and there times the
expected amount of the allylic hydroperoxide of 12. A competing radical chain oxidation reaction is proposed to account for
these products and the stoichiometry of the ozonolysis. The initial reaction in the ozonolysis of 1 is proposed to be an electron
transfer reaction that is calculated to be exothermic by
>35 Kcal/mol. Thr resulting radical ions initiate the radical chain oxidation and combine to form the oxygenated epoxide 9 of
1. Loss of singlet oxygen from 9 forms the epoxide 10, which rearrange to 7. At -95ºC the zwitterion from 10 is trapped by
CD3OD to produce a mixture of 7 with one a OCD3 group and pentamethoxyethanol with one b OCD3 group from which a
CH3OD group is lost at ~ -10ºC to form more deuterated ester.