Bulletin of the Chemical Society of Japan p. 2639 - 2646 (1994)
Update date:2022-08-11
Topics:
Pandiarajan, Karuppiah
Kabilan, Senthamaraikannan
Sankar, Punnaivanam
Kolehmainen,Erkki
Nevalainen, Tapio
Kauppinen, Reijo
13C, 15N, and 17O NMR spectra have been recorded for 4-nitroanisole (1), its 2-methyl-, 2-chloro-, 2-bromo-, 2-iodo-, 2,6-diamethyl-, 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 steric enhancement of resonance using methoxyl oxygen chemical shifts, analysis of these chemical shifts in di-ortho-substituted anisoles 6-9 and 6a furnishes evidence for steric inhibition of resonance.However, 15N chemical shifts are of no use in studying these phenomena.Semiempirical molecular orbital calculations using AM1 Hamiltonian suggest that the methoxyl group is coplanar with the benzene ring in anisole, 4-nitroanisole and 2-substituted-4-nitroanisoles but is perpendicular to the benzene ring in 2,6-disubstituted-4-nitroanisoles.Moreover, in 2-substituted-4-nitroanisoles the O-methyl group is anti to the 2-substituent.
View MoreZhonghao (dalian) Research and Design Institute of Chemical Industry Co., Ltd
Contact:+86 411 84674606
Address:201, Huangpu Road , Shahekou District, Dalian ,116023-China
QINGDAO NEW FLOURISH INTERNATIOANAL TRADE CO., LTD.
Contact:+86 532 80861829
Address:No. 1, Yinchuan East Road, 266061, Qingdao, China
Weifang Yukai Chemical Co.,Ltd.
website:http://www.yukaichem.com/en.html
Contact:+86-536-8865336
Address:binhai economic development zone,262737 shangdong,china
website:http://www.lidepharma.com
Contact:+86-25-58409506
Address:11F, Building A1, No.288 North Zhongshan Road, Gulou District, Nanjing,210003, P.R.China.
CGeneTech (Suzhou, China) Co., Ltd.
Contact:+86-512-62956962
Address:Room 101,Bld C11,218 Xinghu Rd.,Suzhou industrial Park
Doi:10.1002/ejic.201701442
(2018)Doi:10.1007/s10562-017-2284-1
(2018)Doi:10.1023/A:1022196617956
(2003)Doi:10.1021/jo00228a027
(1987)Doi:10.1139/v68-429
(1968)Doi:10.1021/acs.orglett.8b02303
(2018)