Benzoic acid, 2,4-dihydroxy-, effect

In a recent modification of the second synthesis (50S) effected for fluvibactin (45) an o-xylene protection group was proposed (reaction of 2,3-dihydroxy-benzoic acid methyl ester with 1,2-di(bromomethyl)benzene) which could be removed later by hydrogenolysis. The formation of the oxazoline ring from protected DHB-L-threonine methyl ester was achieved with Mo(VI) catalysts (e.g. (NH4)2Mo04) without affecting the chiral centers. Derivatization of the primary amino groups of norspermidine with the protected DHB methyl ester was catalyzed by Sb(OC2115)3. 

Benzimidazole derivatives, III, 161 Benzimidazole rule of rotation, I, 21 1,3-Benzodioxan, 8,8 -methyIenebis(6- nitro-), III, xvii Benzoic acid, cellulose esters, I, 320 labelled with isotopic C, III, 231 starch esters, I, 302, 303 —, 2,4-dihydroxy-, effect on conductivity of boric acid, IV, 195 —, 2,4,5-trihydroxy-, effect on conductivity of boric acid, IV, 195 —, 3,4,5-trihydroxy-. See Gallic acid. 

The solvent isotope effect in the decarboxylation of 2,4-dihydroxy-benzoic acid is ( atcoohJhjO /( ArcooD)D,o = 6.25. The solvent isotope effect on the acid ionization constant of 2,4-dihydroxybenzoic acid has been determined separately, by potentiometric methods ... 

It has been found by experiment that substances of the type RX, containing two different haptenic groups, do not form precipitates with either anti-R serum or anti-X serum Alone, but do form precipitates with a mixture of the two specific antisera. This provides proof of the effective bivalence of the dihaptenic precipitating antigen, and thus furnishes further evidence for e framework theory of antigen-antibody precipitation. In these experiments tiie anti-R serum and anti-X serum were made by injecting rabbits with sheep serum coupled with diazotized p-arsanilic add and diazotized p-aminobenzoic acid, respectively, and the RX substances used were l-amino-2-/>-(p-azophenylazo)-phenylarsonic acid-3,6-disul-fonic add 7-p-(p-azophenylazo)-benzoic acid-8-hy-droxynaphthalene and l,8-dihydroxy-2-/>-azo-phenylarsonic acid-3,6-disulfonic acid-7-p-(p-azo-phenylazo)-benzoic acid-naphthalene. 

Piantadosi etal. (1995) investigated the effects of hyperbaric oxygen on generation of highly reactive hydroxyl radical in the brain after CO poisoning in Sprague-Dawly rats using nonenzymatic hy-droxylation of salicylic acid to 2,3 dihydroxy-benzoic acid (formula [178]) as a probe. In control studies, the concentrations of 2,3-dihydroxybenzoic... 

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