<b>Carbonium Ions. XI. Nuclear Magnetic Resonance Spectra of the Aliphatic Alkenyl Cations</b>

Deno, N. C.; Richey, Herman G.; Friedman, Norman R.; Hodge, J. D.; Houser, John J.; Pittman, Charles U.

doi:10.1021/ja00902a025

Cited by 86 publications

(41 citation statements)

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“…This assignment is based on (a) the presence of +C-CI-I3 methyl groups a t 7.44 7, in the region found for dienylic ions; (b) the presence of a sharp peak a t 7.92 7, very characteristic of a methyl group attached to carbon atoms between carbonium ion centers, but of an intensity indicating only 40y0 of the area expected if the solution contained pure VIII; (c) the presence of three peaks in the region where protons attached to carbon atoms between carbonium ion centers are found, two for ion VII and one for ion VIII; and (d) the gem-dimethyl protons found a t 8.68 7, indicating that they are one carbon removed from a carbonium ion center, i.e., compare with the higher signals found in ion VI and also with the extensive table of proton positions elaborated by Deno et al (8). There is also a precedent for the formation of these two compounds.…”

Section: The Carbonium Ionssupporting

confidence: 54%

The Preparation of a Trivinyl Carbonium Ion

Sorensen¹

1965

Can. J. Chem.

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The preparation of a stable trivinyl carbonium ion is described. A detailed evaluation and comparison of the n.m.r. spectrum of this ion with other stable carbonium ions, coupled with the use of ultraviolet spectroscopy, is used for the structure proof. The synthesis of the necessary tetraene precurser and the cyclization reactions of the above ion are also described. Comparisons of the cyclization rate of various stable carbonium ions are given and a n attempt is made t o evaluate the resonance stability of the trivinyl carbonium ion.

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Section: The Carbonium Ionssupporting

confidence: 54%

The Preparation of a Trivinyl Carbonium Ion

Sorensen¹

1965

Can. J. Chem.

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“…The problem, really, is getting the triene into the sulfuric acid in a very dilute form, so that polymerization is minimized or avoided. Deno et al (6) have discussed this problem and were able to prepare reasonably pure cyclopentenyl cations by adding the organic colnpound through a capillary to the sulfuric acid, kept a t 0 "C. Trienes, however, seem to be even more reactive and another method was necessary. We have added the trienes, in the gas phase a t about 0.01 mm, to a sulfuric acid solution spread out over the bottom of a conical flask ( Fig.…”

Section: Introductionmentioning

confidence: 99%

“…Using the high-dilution procedure employed by Deno et al (6) (see experimental), we have recovered the dienes from the carbonium ion IV in 80% yield. These were separated by vapor-phase chromatography (g.1.c.)…”

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confidence: 99%

The Synthesis and Reactions of Divinyl Carbonium Ions

Sorensen¹

1964

Can. J. Chem.

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A number of alkyl-substituted trienes have been protonated. In some cases, the existence of divinyl carbonium ions can be shown, while in others, a cyclization reaction leading to, cyclopentenyl carbonium ions takes place so rapidly t h a t the presumed initially formed divinyl carbonium is never observed. Steric arguments are invoked to explain these differences. Complete n.m.r. and ultraviolet spectral data are presented in support of the assigned carbonium-ion structures. Some evidence has been obtained regarding the mechanism of the cyclization reaction. Finally, one of the cyclic carbonium ions is decomposed and the cyclic dienes which are produced are isolated and characterized.

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“…concentrated sulfuric acid solutions exist as mesomeric carbonium ions (2), with an absorp-, tion maximum near 287 mp (3). However, no systematic study of the protonation of simple a,P-unsaturated ketones has been undertaken.…”

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confidence: 99%