M-Hydroxybenzoic acid

Interpretation of spectra. The infrared spectrum of m-hydroxybenzoic acid (solid ground in Nujol) is shown in Fig. A, 7, 1. The more important bands may be interpreted as follows. 

Bromomethyl-3-methylquinoxaline (273) and m-hydroxybenzoic acid (274) gave either 2-(m-hydroxybenzoyloxymethyl)-3-methylquinoxaline (275) [KOH (1 mol), EtOH, reflux, 2h 69%] or 2-(m-carboxyphenoxymethyl)-3-methylquinoxaline (276) [KOH (2 mol), EtOH, 50°C—>reflux, 1 h 44%] p-hydroxybenzoic acid reacted similarly but o-hydroxybenzoic acid (salicylic acid) gave only the isomer of product (275) even in the presence of KOH (2 mol). It would seem that the substrate (275) preferred to react at the phenolic anion rather than at the carboxylate anion when both were present... 

How is m-hydroxybenzoic acid prepared Discuss the reduction of salicylic acid to pimelic acid (Einhom). 

Materials. Phthalic anhydride (PA), adipic acid (AA), neopentyl glycol (NPG), p-hydroxybenzoic acid (PHBA), salycilic acid, m-hydroxybenzoic acid (MHBA), xylene, and methyl isobutyl ketone (MIBK) were purchased from Aldrich. p-Toluenesulfonic acid (p-TSA) was purchased from Matheson. "Aromatic 150" solvent and "Resimene 7A6", a hexakis(methyloxymethyl)melamine (HMMM) resin were supplied by Exxon and Monsanto, respectively. "Bonderite 1000" pretreated cold-rolled steel panels 3"x9"x2AGA were purchased from Parker. 

Modification of the PA/AA/NPG diol with salicylic and with m-hydroxybenzoic acids apparently did not proceed to completion. The products appeared amorphous by polarizing microscopy. 

The m-hydroxybenzoic acid modified oligomers cured at 175° to give hard but brittle films. All failed the 80 in-lb impact resistance test. 

Turowska etal. [166] have studied adsorption of m-hydroxybenzoic acid in aqueous solutions on the dropping mercury electrode and determined the surface tension, differential capacity, and the potential of zero charge for this system. 

Hydroxybenzoic acid (m.p. 159) (Salicylic acid) m-Hydroxybenzoic acid (m.p. 201) -Hydroxybenzoic acid (m.p. 214)... 

Unlike salicylic acid, m-hydroxybenzoic acid does not undergo the Fnedel-Crafts reaction, it can be converted m 80% yield to m-aminophenoi by the Schmidt reaction, which involves treating the acid with hydrazoic add in trichloroethylene in the presence of sulfuric add at 40°C. m-Hydroxybcnzoic acid is reported as an intermediate in the manufacture of germicides, preservatives, pharmaceuticals, and plastidzer. 

The method is often important in the preparation of hydroxy derivatives of compounds the groups in which render them difficult to prepare by more direct means. m-Hydroxybenzoic acid is such a compound. It is obtained by nitration of benzoic acid followed by reduction to m-amino-benzoic and application of the present reaction (see below). 

Preparation 132.—m-Hydroxybenzoic Acid (l-Hydroxy-3-carboxy-benzene). 

D-Malic acid (unnatural) 0.0761 m-Hydroxybenzoic acid No effect... 

Better results are obtained in the reduction of o- and m-hydroxybenzoic acid ... 

The residual solution is acidified and extracted with ether removal of the ether and recrystallization of the residue from water affords 6.5 g. (94.2%) of m-hydroxybenzoic acid, m.p. 202° (corr.). 

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