Bis[(1-phenyl-1-cyclopropyl)carbonyl]peroxide

Abstract

Abstract. C20HlaO4, M r = 322.34, monoclinic, C2/c or Cc, a = 14.65 (2), b = 11.21 (2), c = 11.10 (2)A, fl= 106.6(1) ° , U= 1747.1A3, Z=4, D,,,= 1.25, Dx= 1.26 Mg m -3, Cu Ka radiation, 2 = 1.5418/~, R = 0.060 for 765 unique reflexions. The title compound decomposes in solution at a rate significantly greater than those of related peroxides: the molecular structure has been determined to explore possible steric reasons for this.

(R,R,S,S)-Bis-[(trans-2-phenyl-1-cyclopropyl)carbonyl] peroxide, C20H18O4

“…molecular interaction; the usual 90 ° torsion angle could bring adjacent molecules even closer together with a reduction in stability of the crystal lattice. The phenyl and carbonyl groups are both able to adopt the preferred bisected conformation (Jason & Ibers, 1977) with respect to the cyclopropane ring C(4)-C(5)-C(6), unlike the situation in the isomeric bis[(1-phenyl-1-cyclopropyl)carbonyl] peroxide where there are steric constraints (Bethell, Chadwick, Harding & Maling, 1982). Further, the C-C bond lengths in the three-membered ring show a combination of vicinal bond lengthening and distal bond shortening as previously noted (Allen, 1980), the effect of the carbonyl group appearing to dominate as in the isomeric peroxide.…”

“…In the course of a programme attempting to relate the structures of diacyl peroxides with their kinetic and spectroscopic behaviour on thermolysis, we have determined the molecular structures of bis [(1-phenyl-l-cyclpropyl)carbonyl] peroxide (Bethell, Chadwick, Harding & Maling, 1982) and transcinnamoyl peroxide (Bethell, Chadwick, Harding & Maling, 1984). The present peroxide (I) was investigated for determination particularly of the degree of conjugation of the phenyl, cyclopropyl and carbonyl groups in it in comparison with analogous moieties in the other two molecules.…”