461670-18-8Relevant articles and documents
Electrophilic Aromatic Substitution. Part 25. The Nitration in Aqueous Sulphuric Acid of Some Cinnamic Acids and Other Styrene Derivatives
Moodie, Roy B.,Schofield, Kenneth,Taylor, Peter G.,Baillie, Philip J.
, p. 842 - 847 (2007/10/02)
The rates of nitration of ethyl cinnamate, cinnamic acid, β-nitrostyrene, and trimethyl(styryl)ammonium ion in sulphuric acid of a range of concentrations have been determined.The nitrovinyl and the trimethyl(vinyl)-ammonium groups deactivate the aromatic nucleus by factors of ca. 330 and 60, respectively.The yields of products from ethyl cinnamate and β-nitrostyrene, nitrated over a range of sulphuric acid concentrations, are reported.With ethyl cinnamate the o:p ratio falls with increasing acidity.The acidity dependences of the rates of reaction of ethyl-4-nitrocinnamate, 4-nitrocinnamic acid, ethyl 3-nitrocinnamate, and 3-nitrocinnamic acid with nitric acid in sulphuric acid show the primary reaction in each case to be attack by the nitronium ion (at the β-carbon atom).The reactions are completed by addition, giving nitroalcohols.A similar but much slower reaction occurs with β,4-dinitrostyrene.In every case the nitroalcohol decomposes in concentrated sulphuric acid to give the nitrobenzaldehyde.With absolute nitric acid, ethyl 4-nitrocinnamate gives the side-chain nitro-nitrate by formal syn-addition.Addition of nitromethane to the reaction solution leads to addition in both stereochemical modes.The nitro-nitrate gives the nitro-alcohol in sulphuric acid, but in aqueous media gives ethyl α-nitro-β-(4-nitrophenyl)acrylates.These apparent side-chain nitrations are thus addition-elimination reactions, as suggested by van der Lee.Similar processes have been detected in the cases of 4-nitrocinnamic acid and β,4-dinitrostyrene.
