Benzoic hydroxy-, bromination

Suggest syntheses for TMs (9) and (10) needed as intermediates TM (9) in the synthesis of brominated hydroxy benzoic acids and TM (10) in the synthesis of model compounds for studying biological mechanisms of ester hydrolysis,... 

When 2-hydroxy benzoic acid (salicylic acid) is treated with excess bromine in aqueous solution, it forms 2,4,6-tribromobenzenol. Write a reasonable mechanism for this reaction. Would you expect the same type of reaction to occur with 3-hydroxy-benzoic acid ... 

Dibromo-4-nitrophenol has been prepared by the nitration of 2,6-dibromophenol1 or of dibromophenol sulfonic acid,2 and by the action of nitric acid on 2,6-dibromo-4-nitroso-phenol3 or on 2,4,6-tribromophenol.4 It has been obtained from the corresponding ethyl ether 5 and by the action of bromine on />-nitrosophenol,6 4,6-dibromo-2-nitrophenol,7 5-nitro-2-hydroxy-benzoic acid,8 and 5-nitro-2-hydroxybenzenesulfonic acid.9 The dibromination of />-nitrophenol I0>13 has been carried out in sulfuric acid solution 11 and in the presence of aluminum chloride.12 The method described here is essentially that of M"hlau and Uhlmann.13... 

On bromination of o- or /7-hydroxy- or o- or /7-amino-benzoic acid, or the corresponding sulfonic acids, even at room temperature, bromine replaces the COOH or S03H group with liberation of C02 or H2S04 as the case may be. At 40-45° the CHO group of o- or /7-hydroxy- or o- or /7-aminobenzaldehyde is also replaced by bromine, with evolution of CO. The end products are 2,4,6-tribromo-phenol or -aniline.460 Thus /7-hydroxybenzoic and sulfanilic acid, for example, can be determined quantitatively by means of O.lN-bromide-bromate solution. 

For a simple bond fission it is doubtful if comparison of the observed isotope effect with the theoretical maximum will give a trustworthy estimate of the position of the transition state small effects are therefore ambiguous as diagnostic tools and must be coupled with other experiments. Another example involving decarboxylation is the bromine-catalysed decomposition of 3,5-dibromo-4-hydroxy-benzoic acid (Eqn. 50) [30b]. 

Oxidation and Bromination of Other Functional Groups. Selective oxidation of alcohols may be achieved using a 1 1 complex of NBS and tetrabutylammonium iodide, whereas 1,2-diols are converted into 1,2-diketones using iV-bromosuccini-mide. An efficient and mild procedure has been reported for the preparation of benzoic acids via oxidation of aromatic carbonyl compounds by employing NBS and mercuric acetate. Selective and efficient oxidation of sulfides to sulfoxides has been achieved with NBS in the presence of /3-cyclodextrin in water. Epoxides and aziridines are conveniently oxidized to the corresponding a-hydroxy or Q -amino ketones using cerium(IV) ammonium nitrate and NBS. ... 

Phenylacetic acids have been prepared from 2,2-dichlorostyrenes by sequential hydroboration and oxidation (Cr03-H2S04) of the intermediate trialkyl borane, and benzoyl benzoic acids (8), not readily available by other routes, have been obtained" in good yield by treatment of phthalic anhydride with aryl-lithiums at — lOO C. Syntheses of some bicyclo [1,1,0] butane-l-carboxylic acids (9) and a range of cyclopropane-1-carboxylic acids [(10) and (II)] have been described. 1-Hydroxy-cyclopropanecarboxylic acids (13) have been prepared from the hydroxy-cyclobutanone derivatives (12), following bromination and hydrolysis. 

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