ENTHALPIES OF FORMATION OF CYCLIC ALKYL PEROXIDES - DIOXANE, 1,2-DIOXETANE, 1,2-DIOXOLANE, AND 1,2-DIOXANE

Enthalpies of formation of four cyclic alkyl peroxides are calculated using ab initio methods. The values are reported as: Delta H(f298)degr ees(dioxirane) = -2.91 +/- 1.34 kcal/mol, Delta H(f298)degrees(1,2-dio xetane) = 1.09 +/- 0.51, Delta H(f298)degrees(1,2-dioxolane) = -27.43 +/- 0.91 kcal/mol, and Delta H(f298)degrees(1,2-dioxane) = -31.74 +/- 0.96 kcal/mol. Enthalpies of formation for 1,2-dioxetane, 1,2-dioxolan e, and 1,2-dioxane are calculated using isodesmic reactions at the MP4 SDTQ/6-31G*//MP2/6-31G* level of theory. These isodesmic reactions ar e 'group balanced'. For dioxirane, reaction energies of two reactions are calculated using the G2 method. The difference of Delta H(f298)deg rees(dioxirane) values determined using these two reactions is within 0.7 kcal/mol. Ring strain energies (in kcal mol-L) are determined as 3 0.7, 26.7, 7.3, 4.0 for dioxirane, 1,2-dioxetane, 1,2-dioxolane, and 1 ,2-dioxane, respectively. Comparisons are also made with a scaled PM3 estimation, and results are in reasonable agreement with the recommend ed values.