Journal of the American Chemical Society p. 2057 - 2062 (1981)
Update date:2022-08-04
Topics:
Geppert, J. T.
Johnson, M. W.
Myhre, P. C.
Woods, S. P.
The solvolytic rearomatizations of the E and Z isomers of 1,4-dimethyl-4-nitrocyclohexadienyl acetate (1) have been examined in aqueous ethanol and in sulfuric acid solutions.Solvolysis of 1 in aqueous ethanol involves the elimination of nitrous acid and the migration of the acetoxyl group to yield 2,5-dimethylphenyl acetate.The kinetic behavior of this solvolytic reaction parallels that of the secondary adduct 4-nitro-3,4,5-trimethylcyclohexadienyl acetate (2).No kinetic isotope effects were detected when 1,4-dimethyl-4-nitrocyclohexadienyl-2,3,5,6-d4 acetate (1-d4) or 1,4-dimethyl-4-nitrocyclohexadienyl-Me-d6 (1-d6) were used as substrates.The collected data suggest a rate-limiting loss of nitrile ion from 1 followed by migration of the acetoxyl group and proton loss.The behavior of Z and E isomers of 1,4-dimethyl-4-nitrocyclohexadienol (3) in aqueous ethanol differs from that of 1 in several ways.The major product of solvolysis is 2,4-dimethylphenol.The rates of solvolysis of the stereoisomers of 3 do not differ appreciably one from another, and the spectral yield is only 30-40percent of that anticipated.These differences are taken to reflect a rate-limiting migration in the solvolysis of 3 rather than a rate-limiting loss of nitrate ion.Solvolysis of 1 in greater than 77percent sulfuric acid gives 1,4-dimethyl-2-nitrobenzene in quantitative yield.The yield of nitro aromatic falls off smoothly as the acid concentration is lowered toward 50percent.Within the 70-50percent acid range, the yield of side-chain substitution products appears to increase, hold roughly constant, and then decrease.Larger yields of nitro aromatic and smaller yields of side-chain substitution product are found when 1-d6 is used as a reactant.The solvolyses in strong acids are discussed in terms of re-formation of the ipso ion and subsequent partitioning.
View MoreContact:+86-25-8776 0031
Address:3-2001 Jiaye Int'l Town, 158 Lushan Road,Nanjing, 210019, China
Contact:86-571-61063068
Address:LINAN
Contact:86-571-85586718
Address:join hands science park,NO.4028 nanhuan road,hanghzou ,zhejiang,china
Contact:+31-24-3886056
Address:Binderskampweg 29 Unit 36
Contact:+86-574-89075960
Address:#100 Xiang Yun Road, New High tech area, Ningbo, China
Doi:10.1016/S0040-4039(01)92051-9
(1974)Doi:10.1002/ejoc.200390157
(2003)Doi:10.1021/jo00902a001
(1975)Doi:10.1039/d0cc07419e
(2021)Doi:10.3390/molecules22122090
(2017)Doi:10.1021/ja00527a048
(1980)