Elimination Reactions of α-Halogenated Ketones. XIII.¹ Substituent Effects upon the Kinetics and Mechanism of Halide Ion Promoted Dehydrobromination of Derivatives of 2-Benzyl-2-bromo-1-indanone in Acetonitrile²

Deuterium isotope effect upon a bimolecular dehydrochlorination of tert-butyl chloride in acetonitrile

“…With this in mind, the value of 3.8 is comparable with the values of between 2 and 3 observed for halide ion promoted elimination from tertiary -halogenated ketones in acetonitrile. 13 Under the same conditions of temperature and solvent, the deuterium isotope effect is significantly higher than the value of 2.62 ± 0.02 observed for El reaction.1 This is consistent with a loose intermediate or transition state (approaching an ion triplet) and incorporating a moderate weakening of a carbon-hydrogen bond in the transition state of the rate-determining step. 13 If a transition state was involved which featured only Sn2 character superimposed upon a El-type process, then one might expect, related to the extent that the positive charge on the a carbon was reduced, an isotope effect for the bimolecular reaction diminished below that observed for the El reaction.…”

“…13 Under the same conditions of temperature and solvent, the deuterium isotope effect is significantly higher than the value of 2.62 ± 0.02 observed for El reaction.1 This is consistent with a loose intermediate or transition state (approaching an ion triplet) and incorporating a moderate weakening of a carbon-hydrogen bond in the transition state of the rate-determining step. 13 If a transition state was involved which featured only Sn2 character superimposed upon a El-type process, then one might expect, related to the extent that the positive charge on the a carbon was reduced, an isotope effect for the bimolecular reaction diminished below that observed for the El reaction. Materials.-Tetraethylammonium chloride and tetraethylammonium perchlorate (Eastman) were recrystallized from acetone and dried under vacuum, at 70°, for 12 hr.…”

Synthesis of heterocyclic compounds by the reactions of exocyclic α,β‐unsaturated ketones

“…The (Z)-diastereomers of compounds 1-7 have been prepared by the photoisomerization of their (E)-isomers (E-1-7) (Scheme 3) [23,44,[56][57][58][59][60][61][62][63].…”

Catalytic decomposition and chemical reduction of diaryliodonium salts. Reactions involving ligand transfer

“…In assessing the extent of carbon-hydrogen bond breaking, and interpreting in terms of a mechanism in which carbon-chlorine heterolysis is running ahead of carbon-hydrogen heterolysis, we are on a scale of roughly 2.6:6 and not, as in most previous investigations, of roughly 1:6. With this in mind, the value of 3.8 is comparable with the values of between 2 and 3 observed for halide ion promoted elimination from tertiary -halogenated ketones in acetonitrile. 13 Under the same conditions of temperature and solvent, the deuterium isotope effect is significantly higher than the value of 2.62 ± 0.02 observed for El reaction.1 This is consistent with a loose intermediate or transition state (approaching an ion triplet) and incorporating a moderate weakening of a carbon-hydrogen bond in the transition state of the rate-determining step.13 If a transition state was involved which featured only Sn2 character superimposed upon a El-type process, then one might expect, related to the extent that the positive charge on the a carbon was reduced, an isotope effect for the bimolecular reaction diminished below that observed for the El reaction.…”

“…Identification was made from solubility characteristics and infrared and nmr spectra. The polymer was found to be insoluble in water, alcohols, acetone, ethylacetate, ether, methylene chloride and pentane but was soluble in dimethylformamide.18 An infrared spectrum (potassium bromide pellet) exhibited strong peaks at 2230 (-CN), 1450 (CH, CH2) and 1050 cm-1 (C-C skeletal) , 13 An nmr spectrum (on a Varían A-60 spectrometer) of a solution in deuterated dimethyl sulfoxide exhibited broad signals at 7.9 and 6.8 and a very weak signal at 2.7.…”