Spiroaromaticity in Spiro[2.3]hexadienyl Anions. Kinetic Acidities in Highly Basic Media

M. F. Semmelhack; R. J. DeFranco; Z. Margolin; J. Stock

doi:10.1021/ja00783a019

Spiroaromaticity in Spiro[2.3]hexadienyl Anions. Kinetic Acidities in Highly Basic Media

M. F. Semmelhack, R. J. DeFranco, Z. Margolin, J. Stock

Research output: Contribution to journal › Article › peer-review

14 Scopus citations

Abstract

Experimental tests for special stabilization (spiroaromaticity) in a spiro[2.3]hexadienyl anion compared with a series of spiro[2.3]hex-4-en-6-yl anions using polarography and kinetic acidity measurements reveal no significant stabilization. The kinetic acidity data were obtained by hydroxide ion catalyzed tritium exchange in dimethyl sulfoxide-water mixtures. The second-order rate constants were determined to be as follows: for 12,4.6 10^-5; for 13, 24.14 × 10^-5; for 14, 2.03 × 10^-5; for 15 (mixture of isomers), 5.70 × 10^-5. Brpnsted coefficients (3) of ca. 0.80 for proton abstraction from the spiro[2.3]hexadiene 12 and spiro[2.3]hex-4-ene 13 suggest that the transition states from both compounds resemble the carbanionic products.

Original language	English (US)
Pages (from-to)	426-432
Number of pages	7
Journal	Journal of the American Chemical Society
Volume	95
Issue number	2
DOIs	https://doi.org/10.1021/ja00783a019
State	Published - Jan 1 1973
Externally published	Yes

All Science Journal Classification (ASJC) codes

Catalysis
General Chemistry
Biochemistry
Colloid and Surface Chemistry

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10.1021/ja00783a019

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title = "Spiroaromaticity in Spiro[2.3]hexadienyl Anions. Kinetic Acidities in Highly Basic Media",

abstract = "Experimental tests for special stabilization (spiroaromaticity) in a spiro[2.3]hexadienyl anion compared with a series of spiro[2.3]hex-4-en-6-yl anions using polarography and kinetic acidity measurements reveal no significant stabilization. The kinetic acidity data were obtained by hydroxide ion catalyzed tritium exchange in dimethyl sulfoxide-water mixtures. The second-order rate constants were determined to be as follows: for 12,4.6 10-5; for 13, 24.14 × 10-5; for 14, 2.03 × 10-5; for 15 (mixture of isomers), 5.70 × 10-5. Brpnsted coefficients (3) of ca. 0.80 for proton abstraction from the spiro[2.3]hexadiene 12 and spiro[2.3]hex-4-ene 13 suggest that the transition states from both compounds resemble the carbanionic products.",

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AU - Semmelhack, M. F.

AU - DeFranco, R. J.

AU - Margolin, Z.

AU - Stock, J.

PY - 1973/1/1

Y1 - 1973/1/1

N2 - Experimental tests for special stabilization (spiroaromaticity) in a spiro[2.3]hexadienyl anion compared with a series of spiro[2.3]hex-4-en-6-yl anions using polarography and kinetic acidity measurements reveal no significant stabilization. The kinetic acidity data were obtained by hydroxide ion catalyzed tritium exchange in dimethyl sulfoxide-water mixtures. The second-order rate constants were determined to be as follows: for 12,4.6 10-5; for 13, 24.14 × 10-5; for 14, 2.03 × 10-5; for 15 (mixture of isomers), 5.70 × 10-5. Brpnsted coefficients (3) of ca. 0.80 for proton abstraction from the spiro[2.3]hexadiene 12 and spiro[2.3]hex-4-ene 13 suggest that the transition states from both compounds resemble the carbanionic products.

AB - Experimental tests for special stabilization (spiroaromaticity) in a spiro[2.3]hexadienyl anion compared with a series of spiro[2.3]hex-4-en-6-yl anions using polarography and kinetic acidity measurements reveal no significant stabilization. The kinetic acidity data were obtained by hydroxide ion catalyzed tritium exchange in dimethyl sulfoxide-water mixtures. The second-order rate constants were determined to be as follows: for 12,4.6 10-5; for 13, 24.14 × 10-5; for 14, 2.03 × 10-5; for 15 (mixture of isomers), 5.70 × 10-5. Brpnsted coefficients (3) of ca. 0.80 for proton abstraction from the spiro[2.3]hexadiene 12 and spiro[2.3]hex-4-ene 13 suggest that the transition states from both compounds resemble the carbanionic products.

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Spiroaromaticity in Spiro[2.3]hexadienyl Anions. Kinetic Acidities in Highly Basic Media

Abstract

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