Arthur Fry

Isotope effects and mechanism in the bromination of alpha- and beta-carbon-14 labeled 4-nitro-4′-methylstilbenes

Abstract In the bromination of 4-nitro-4′-methylstilbene, the carbon-14 αC isotope effect is larger, k/ α k = 1.013, than the α C one, k/ β k = 1.0035. These results support an open carbocation intermediate mechanism with the positive charge on the carbon adjacent to the methyl-containing ring.

Isotope effects and mechanism in the base-promoted dehydrochlorination of 1,1-dichloro-2,2-diarylethanes-1-14C

In the base-promoted dehydrochlorination of 1,1-dichloro-2,2-diphenylethane-1- 14C and its p-nitro analog, the isotope effects, k/14k, are 1.045 and 1.024, respectively. These results support an Elcb-like E2 mechanism for both elimination reactions.

Carbon-14 kinetic isotope effects and mechanism in the solvolysis of 1,1,1-trifluoro-2-phenyl-2-propyl-3-14C p-toluenesulfonate

Abstract In the solvolysis of 1,1,1-trifouoro-2-phenyl-2-propyl-3-14C p -toluenesulfonate there is only a small βC isotope effect, k/βk = 1.008 ± 0.002. The result is as expected for a branching SN 1/E1 reaction (mostly SN1). This is the first example of such a measurement.

Carbon-14 kinetic isotope effects and mechanisms of addition of 2,4-dinitrobenzenesulfenyl chloride to substituted styrenes in the presence of lithium perchlorate☆

The k/αk isotope effect for addition of ArSCI to p-methylstyrene is small and unchanged by addition of LiClO ; k/βk is high and unchanged. For styrene and p-chlorostyrene k/βk values are high and unchanged, while k/αk increases from ∼ 1.025 to ∼ 1.04. p-Methylstyrene reacts through an open carbenium ion and the other two have cyclic intermediates.