Reactions of Unsaturated Compounds with Iodine and Bromine on γ Alumina

Richard M. Pagni, George Kabalka, Richard Boothe, Kevan Gaetano, Lyman J. Stewart, Richard Conaway, Christopher Dial, Donna Gray, Steven Larson, Teresa Luidhardt

Research output: Contribution to journalArticle

68 Citations (Scopus)

Abstract

Iodine reacts with a diverse group of unsaturated substrates in the presence of dehydrated alumina. Aromatic substrates, for example, are iodinated at room temperature by electrophilic aromatic substitution. The yields of the iodinated products can be improved dramatically by running the reaction at 110 %C. Aniline, even at 100 %C, is unreactive, presumably because its nitrogen lone pair is complexed to surface aluminum cations or protons. Alkenes react readily with HI, formed in the reaction of surface hydroxyls with I2, to form alkyl iodides by an ionic mechanism involving carbocations. This is an excellent method for the synthesis of alkyl iodides from alkenes. Alkynes, on the other hand, add I2 (stereospecific, anti) under very mild conditions to form vinyl diiodides in excellent yield. The behavior of Br2 with cyclohexene on alumina is considerably different than that of I2 with cyclohexene. Two products are formed: trans-1,2-dibromocyclohexane (1), which is formed in solution during workup, and trons-1-bromo-2-chlorocyclohexane (2), which is formed on the surface. The chlorine in 2 arises from intrinsic chloride already on the alumina and CC14, the solvent used to adsorb Br2 onto alumina. Further experiments demonstrate that cyclohexene undergoes intergranular hopping, but that Br2 does not.

Original languageEnglish (US)
Pages (from-to)4477-4482
Number of pages6
JournalJournal of Organic Chemistry
Volume53
Issue number19
DOIs
StatePublished - Sep 1 1988
Externally publishedYes

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Unsaturated compounds
Bromine
Aluminum Oxide
Iodine
Alkenes
Iodides
Alkynes
Chlorine
Substrates
Aluminum
Hydroxyl Radical
Cations
Protons
Chlorides
Substitution reactions
Nitrogen
cyclohexene
Experiments
Temperature

All Science Journal Classification (ASJC) codes

  • Organic Chemistry

Cite this

Pagni, R. M., Kabalka, G., Boothe, R., Gaetano, K., Stewart, L. J., Conaway, R., ... Luidhardt, T. (1988). Reactions of Unsaturated Compounds with Iodine and Bromine on γ Alumina. Journal of Organic Chemistry, 53(19), 4477-4482. https://doi.org/10.1021/jo00254a011

Reactions of Unsaturated Compounds with Iodine and Bromine on γ Alumina. / Pagni, Richard M.; Kabalka, George; Boothe, Richard; Gaetano, Kevan; Stewart, Lyman J.; Conaway, Richard; Dial, Christopher; Gray, Donna; Larson, Steven; Luidhardt, Teresa.

In: Journal of Organic Chemistry, Vol. 53, No. 19, 01.09.1988, p. 4477-4482.

Research output: Contribution to journalArticle

Pagni, RM, Kabalka, G, Boothe, R, Gaetano, K, Stewart, LJ, Conaway, R, Dial, C, Gray, D, Larson, S & Luidhardt, T 1988, 'Reactions of Unsaturated Compounds with Iodine and Bromine on γ Alumina', Journal of Organic Chemistry, vol. 53, no. 19, pp. 4477-4482. https://doi.org/10.1021/jo00254a011
Pagni, Richard M. ; Kabalka, George ; Boothe, Richard ; Gaetano, Kevan ; Stewart, Lyman J. ; Conaway, Richard ; Dial, Christopher ; Gray, Donna ; Larson, Steven ; Luidhardt, Teresa. / Reactions of Unsaturated Compounds with Iodine and Bromine on γ Alumina. In: Journal of Organic Chemistry. 1988 ; Vol. 53, No. 19. pp. 4477-4482.
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