31106-74-8Relevant articles and documents
Products of reaction between tetrabromo-substituted ortho- and para-hydroxybenzoic acids and sodium nitrite in CH3COOH
Fadin,Tarasova,Vasin,Shishkin
, p. 1062 - 1070 (2013/01/15)
The reaction of 2,3,5,6-tetrabromo-4-hydroxybenzoic acid with a 10-fold excess of NaNO2 in the glacial acetic acid at 20°C affords tetrabromonitrosophenols whose further transformations under the reaction conditions leads to the formation of a mixture of 2,4,5,6-tetrabromo-p-quinone diazide and tetrabromo-p- and -o-nitrophenols in the molar ratio 37 : 2 : 1. Under similar conditions the 3,4,5,6-tetrabromo-2-hydroxybenzoic acid is converted into a mixture of 3,4,5,6-tetrabromo-o-quinone diazide with the same nitrophenols in the ratio 13 : 1 : 3. The reaction of sodium 2,3,5,6-tetrabromo-4-hydroxy-benzoate with NaNO2 in dilute acetic acid resulted in a quantitative yield of tetrabromo-p-quinone monooxime. Pleiades Publishing, Ltd., 2012.
Multinuclear Magnetic Resonance Spectroscopic and Semiempirical Molecular Orbital (AM1) Studies of Substituted Anisoles
Pandiarajan, Karuppiah,Kabilan, Senthamaraikannan,Sankar, Punnaivanam,Kolehmainen,Erkki,Nevalainen, Tapio,Kauppinen, Reijo
, p. 2639 - 2646 (2007/10/02)
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.
