Carbonium Ion Rearrangements. VI. Mechanism of the

Carbonium Ion Rearrangements. VI. Mechanism of the Rearrangement of Neopentyl Compounds. Gerasimos J. Karabatsos, Chester E. Orzech, and Seymour...
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G. J. KARABATSOS, C. E. ORZECH, JR.,

1994 [CONTRIBUTIOS FROM

THE

S. MEYERSON

AND

Vol. 86

KEDZIECHEMICAL LABORATORY, MICHIGAN STATE UXIVERSITY, EASTLASSISG,MICH, A I - D AXD DEVELOPMENT DEPARTMEST, AMERICANOIL Co , WHITING,I N D]

Carbonium Ion Rearrangements. VI.

THE

RESEARCH

Mechanism of the Rearrangement of Neopentyl Compounds

BY GERASIMOS J. KARABATSOS,'~ CHESTERE. ORZECH, JR

, I b AND

SEYMOUR MEYERSON'~

RECEIVEDDECEMBER 17, 1963 The t-amyl alcohols obtained from the deamination of neopentyl-l-13C and neopentyl-l,l-d2-amines,from the solvolysis of neopentyl-l-13C and neopentyl-l,l-dZ tosylates, and from the solvolysis of n e ~ p e n t y l - l - ' ~ C iodide were analyzed by n.m.r. and mass spectrometry. Also analyzed by n.m.r. was the t-amyl chloride obtained from the reaction of neopentyl-l-13C alcohol with triphenyl phosphite and benzyl chloride. The label originally present a t C-1 of the neopentyl compounds always ends up a t C-3 of the t-amyl compounds. The results rule out the intervention of 1,3-hydride shifts, protonated cyclopropanes, or hydrogen-bridged ions during the rearrangement.

The intermediacy of cationated cyclopropanes in gas-phase ionic decompositions in the mass spectrometer is well documented.2 The suggestion3 that such species may intervene as intermediates in liquid phase carbonium ion rearrangements, however, has not been substantiated. Conversion of the neopentyl group to the t-amyl group by the reaction of neopentyll-13C alcohol with hydrogen bromide4 or by deoxideation of neopentyl- l,I-& alcohol5 proceeds with no perceptible intervention of protonated cyclopropanes. Nevertheless, the recently reported 1,3-hydride shifts6,' and proton exchange between cyclopropane and sulfuric acid* might be interpreted in terms of protonated cyclopropanes, either symmetrical (I) or hydrogen bridged (11).