ISSN:
0030-493X
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The capability of the cyclopropyl group to conjugate with Unsaturated systems or to delocalize an adjacent positive charge is compared with that of a double bond, and is tested by the determination of the gas-phase basicity (GB) of various methyl-substituted cyclopropylbenzenes, α-methyl styrenes, and biphenyls by Fourier-transform ion cyclotron resonance. The site of the gas-phase protonation in the cyclopropylbenzene is established at the three-membered ring, based on analogy with the trends of GBs in the styrene system upon methyl substitution at the aromatic meta and para positions. The diverse nature of the conjugative interaction of a cyclopropyl group and of a double bond toward an aromatic ring is manifested, instead, in the different behaviour toward a steric perturbation. The cyclopropyl group adopts the bisected conformation in cyclopropylbenzene, because it tolerates the steric perturbation of a methyl group, intentionally placed in the ortho position, more easily than the double bond, which adopts a coplanar conformation in the isomeric α-methyl styrene.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/oms.1210240214
Permalink
