Structural effects on rates and equilibrium. XVII. Electronic effects of substituents on the stabilities of carbon-carbon double bonds

Phenylthioallyl and phenylthiovinyl phosphine oxides: synthesis of 1-phenylthiobutadienes and a three-component synthesis of ketones

“…(54), like (36), result from x-sulphenylation followed by a [1,3]PhS shift,17 and that the vinyl sulphides (48) and (51), like (37), result from equilibration by proton transfer as PhS is strongly double bond attracting. 22 We confirmed that reprotonation of the anion of (54) occurred cz to P h 2 P 0 by treatment of (54) with BuLi followed by water. The only product was the vinyl sulphide (55).…”

Impact of upwardly revised Δ H f 0 of primary, secondary, and tertiary radicals on mechanistic constructs in thermal reorganizations

“…In the case of cyano, the radical-stabilizing power vis-d-vis hydrogen may be taken as 8 kcal/mol (64) (65). With a value of 2 kcal/mol assigned to C-I, agreement is not good.…”

Conjugative Interaction in Styrenes

“…Thermochemical consequences of the interaction of a wide variety of substituents with the carbon−carbon double bond have a long history in organic chemistry. The subject has been exhaustively reviewed by Hine and his co-workers . Thermochemical information about styrenes being sparse, this paper is focused on the enthalpy and entropy of conjugation of the phenyl group and the influence of substituents and configuration on deviations from coplanarity.…”

“…The great majority of conjugative interactions has been obtained by the measurement of equilibrium constants in the system of α,β-conjugated and β,γ-unconjugated isomers at a single temperature and has therefore furnished free energies of conjugation. Theoretical scrutiny has had to be based on the assumption that free energies and enthalpies are equal for practical purposes, that is, that entropies of conjugation can be ignored . Evaluation of this assumption is but one justification for dissecting free energy of conjugation into its components.…”