102260-58-2Relevant articles and documents
The Bromination of Salicylate Anions. Evidence for the Participation of the Ortho Carboxylate Group
Tee, Oswald S.,Iyengar, N. Rani
, p. 4468 - 4473 (1985)
Salicylate monoanions show reduced selectivity toward bromine in aqueous solution when compared to similarly substituted phenols.In particular, 5-substituted salicylate ions show ρ+ = -2.69 whereas for para-substituted phenols ρ+ = -5.21.From this and other evidence it is argued that bromine attack on such ions may involve proton transfer from the hydroxyl group to the o-carboxylate to which it is hydrogen bonded. 5-Methylsalicyclic acid (8a) forms, in part, an unstable cyclohexadienone (13) resulting from ipso bromine attack.The breakdown of 13 shows intramolecular catalysis by the o-COOH group, which has an effective molarity of 58 M.The microscopic reverse reaction of bromine on the anion 8a must, therefore, involve the o-CO2- group, as suggested above.Implications with respect to the activating effect of hydroxyl groups on cation-forming reactions are discussed.
Enolization of the benzocyclohexadienone formed during the bromination of 1-naphthol in aqueous solution
Tee, Oswald S.,Iyengar, N. Rani
, p. 1714 - 1718 (2007/10/02)
Benzo-4-bromo-2,5-cyclohexadienone (5) has been observed in the aqueous bromination of 1-naphthol and the kinetics of its enolization to 4-bromo-1-naphthol have been studied in the pH range 0-7.This process is catalyzed by the proton, hydroxide ion, water, buffer acids, and by buffer bases.For ctalysis by general bases the Broensted β = 0.59 whereas catalysis by general acids has a value of α ca. 0.These findings are very similar to those obtained previously for the 4-bromo-2,5-cyclohexadienone 2b, formed during the aqueous bromination of 2,6-dimethylphenol.The mechanistic implications of the results are discussed.The enolization of the related dienone 8, formed from bromine and 1-naphthol-2-carboxylic acid, was also studied.At acidic pHs the dienone 8 is much more reactive than 5, with the 2-COOH behaving as an internal catalyst having an "effective molarity" of about 110 M.The enolization of 8 is also catalyzed by buffer bases.
