K. Pandiarajan, S. Kabilan, P. Sankar
Oct 1, 1994
Citations
0
Influential Citations
2
Citations
Journal
Bulletin of the Chemical Society of Japan
Abstract
13C, 15N, and 17O NMR spectra have been recorded for 4-nitroanisole (1), its 2-methyl-, 2-chloro-, 2-bromo-, 2-iodo-, 2,6-dimethyl-, 2,6-dichloro-, 2,6-dibromo-, and 2,6-diiodo-derivatives 2—9, also nitrobenzene (1a), its 3-methyl-, 3-chloro-, 3-bromo-, and 3-iodo-derivatives 2a—5a and 3,5-dichloro- and 3,5-dibromo-derivatives 7a and 8a. Analysis of the chemical shifts of carbon bearing nitro group and nitro oxygens in these compounds suggests that presence of one substituent ortho- to the methoxyl group enhances its resonance interaction with the benzene ring whereas presence of two ortho-substituents inhibits this resonance. However, in no case the resonance is completely inhibited. The extent of enhancement or inhibition is almost independent of the nature of the ortho-substituent. This conclusion has also been arrived by analyzing the reported chemical shifts of the para-carbons in anisoles 1b—9b and the corresponding carbons in benzene derivatives 1c—9c. Though evidence could not be obtained for ster...