M-hydroxy benzoic acid

In his later studies Wolffenstein found that the hydroxyl group could be introduced in this way into the aromatic ring, not only in the case of benzene but also with its derivatives as well. For example, benzoic acid yielded trinitro-m-hydroxy-benzoic acid in the presence of mercuric nitrate ... 

Tableau 3.5 defines the equilibrium conditions of 2 x 10 M hydroxy benzoic acid.

We have reported a convenient method for the preparation of polyesters by direct polycondensation reaction of p-hydroxybenzoic acids using triphenyl phosphite or phenylphosphine dichloride in pyridine. However, the poly condensation of m-hydroxy-benzoic acid or of a combination of aromatic dicarboxylic acids and bisphenols gives polymers only in low yields34. ... 

Hexachlorocyclotriphosphatriazeneb (also known as phosphonitrilic chloride trimer, PNC) has also been found to promote the polycondensation of carboxylic acids and phenols to yield carboxylic esters in high yields. This process has been successfully applied to the preparation of polyesters directly from p- and m-hydroxy-benzoic acids and also from a combination of dicarboxylic acids and bisphenols (Table 18)13, especially from 4-hydroxy 3,5-dimethoxy benzoic acid (syringic acid) in high yield. 

Fig. 4. Hydrogenation of the ring of acid-substituted aromatic compounds using 5% Rh on AhOa powder as catalyst and 100 ml. solvent. 1) 1 g. catalyst, 0.5 ml. benzene, HOAc 2) 1 g. catalyst, 500 mg. benzoic acid HOAc 3) 1 g. catalyst, 500 mg. phthalic acid, HaO 4) 1 g. catalyst, 500 mg. m-hydroxy-benzoic acid, HOAc 5) 1 g. catalyst, 500 mg. phthalic acid, HOAc 6) 1 g. catalyst, 500 mg. salicylic acid, HOAc 7) 1 g. catalyst, 500 mg. p-hydroxy-benzoic acid, HOAc.

Yerlikaya Zekeriya, Aksoy Serpil, Bayramli Erdal. (2002). Synthesis and Melt Spinning of Fully Aromatic Thermotropic Liquid Crystalline Copolyesters Containing m-hydroxy-benzoic Acid Units. J. Appl. Polym. Sci, 85(12), 2580-2587. 

Benzoic acid, /(-chloro-Benzoic acid, m-hydroxy-Benzoic acid, o-hydroxy-Benzoic acid, p-hydroxy-Benzoic acid, mercapto-Benzoic acid, methoxy-Benzoic acid, methyl-Benzoic acid, o-, m-, and... 

When the phenol contains a carboxylic acid group, e.g., m- or p-hydroxy-benzoic acid, the acetylated derivative will of course remain in solution as the sodium salt, but is precipitated when the solution is subsequently acidified. Salicylic acid, however, cannot be acetylated under these conditions. 

Problam 16.14 Although p-hydroxy benzoic acid is less acidic than benzoic acid, salicyclic (o-hydroxybenzoic) acid (X, = 105 x 10 ) is 15 times more acidic than benzoic acid. Explain. M... 

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... 

Potentiometry. The dissociation constants of 4-alkylamido-2-hydroxy-benzoic acids in the presence of Brij 35 micelles were measured at 25°C and 0.10 M ionic strength (NaNO ). The ligand (0.002 M) was titrated with 1 M NaOH using a 655-Multi-Dosimat automated titrator (Metrohm), equipped with a 605-pH-meter and a 614-Impulsomat unit. 

New Orthoform m-Amine p-hydroxy benzoic acid, methyl ester... 

A diastereoselective epoxidation of a tetrasubstituted double bond was accomplished with mCPBA in the total synthesis of (-)-21-isopentenylpaxilline by A.B. Smith et al." The tetracyclic lactone substrate containing the tetrasubstituted double bond was exposed to mCPBA in toluene at room temperature. The reaction mixture also contained sodium bicarbonate to neutralize the by-product m-chloro benzoic acid. The epoxidation exclusively took place from the less hindered a-face of the molecule. At a later stage, this epoxide was converted to the y-hydroxy enone moiety present in the natural product. 

Armstrong et al. (All, A14) have found the following 3-hydroxy-phenyl acids in normal human urine m-hydroxy-benzoic, -hippuric, -phenylacetic, -phenylpropionic, and -phenylhydracrylic (Fig. 9). 

It should be noted that the relative rates of attack of OH at the ortho-, meta-, and para-positions of benzoic acid cannot be derived from the observed G-values of end products in anoxia. The G-values will be influenced strongly by the redox potentials of the intermediate radicals as well as by steric factors. From our results it appears that the p-hydroxy-benzoic acid radical probably acts as a reducing agent, whereas o-, and m-hydroxybenzoic acid radicals probably are oxidizing entities in dis-mutation reactions taking place in anoxia. 

N-Methylisoxazolidines, e.g. (384), are smoothly converted into iV-hydroxy-tetrahydro-l,3-oxazines, e.g. (385), in good yield by oxidation with m-chloroper-benzoic acid in one case the intermediate nitrone can be trapped (as an adduct with methyl acrylate) (Scheme 149). ... 

Shapley et al. [125] computed the pX a of benzoic and o-, m-, and p-hydroxy benzoic acids in order to understand the higher ability of the o-hydroxy benzoate to complex to the cationic surfactant headgroups in micelles and adsorbed films. Although the values did not show good agreement with the experimental data, the calculations provided a clear explanation for the unusual behavior of the o-hydroxy benzoate. 

A -Dihydrojgrdiphenylmethaxie,. Leaflets or needles from hot HoO. M.p. 158°. Sol. EtOH, EtjO. alkalis. Mod. sol. CHCI3, InsoLCSa. Non-volatilemsteam. K.OHfusion — phenol -h p-hydroxy benzoic acid. 

Guezala et al. [420] studied the viscoelastic behaviour of solutions of the thermotropic main chain liquid crystalline X7G (see Fig. 160), Le. a copolyester (M 20 kg/mol) of poly(hydroxy benzoic acid) (60%) and poly(ethylene tere-phthalate) (40%) in m-cresoi the material used is non-random with respect to chain structure and domains of poly(hydroxy benzoic acid) have been reported. Solutions were studied, varying in concentration from 2.5 to 45 wt%. Special care was taken to avoid water absorption, because in its presence degradation and/or trans terification might occur. 

Ethanolyses of 4-nitrophenyl esters of benzoic, 4-methoxybenzoic, and 4-hydroxy-benzoic acids in the presence of alkali metal oxides (EtOM M = Li, Na, K) were catalysed more strongly by ion pairs than free EtO . Evidence was presented which supported the involvement of two metal ions in the transesteriflcation of 4-nitrophenyl 4-hydroxybenzoate, but only one metal ion for the other two esters. ... 

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