2- hydroxybenzoic acid synthesis

Kolbe-Schmitt reaction (Section 24 10) The high pressure re action of the sodium salt of a phenol with carbon dioxide to give an o hydroxybenzoic acid The Kolbe-Schmitt reac tion IS used to prepare salicylic acid in the synthesis of as pinn... 

Raghavan and coworkers have reported on the preparation of 4-hydroxybenzoic add esters (parabans) possessing antimicrobial activity by esterification of 4-hydroxybenzoic acid (Scheme 6.153) [299]. Optimum results were obtained using the alcohol (1-butanol) as solvent in the presence of catalytic amounts of zinc(II) chloride or p-toluenesulfonic acid (pTsOH) under atmospheric conditions. After 5 min of microwave irradiation at 120 °C, ca. 40% conversion to the ester was observed. Related studies on the synthesis of long-chain aliphatic esters have been described by Mariani and coworkers [300]. 

In a synthesis reaction, an impure sample of aspirin was prepared from 2-hydroxybenzoic acid and ethanoic anhydride. The reaction mixture was heated for approximately 10 minutes. 

Synthesis of Cross-Linkable Heterogeneous Oligoester Diols by Direct Esterification with p-Hydroxybenzoic Acid... 

Esterification is frequendy carried out by direct reaction of the carboxylic acid with an alcohol in the presence of a small amount of mineral acid, usually concentrated sulfuric or hydrochloric acid. The esters of commercial importance in both 0- and -hydroxybenzoic acid are the methyl esters. Direct esterification has the advantage of being a single-step synthesis, but being an equilibrium it is easily reversed. The reaction to the ester is driven by either of... 

Kaneda et al. synthesized [61] a series of high molecular weight extended chain copolyimides (XV) by the reaction of PMDA and 3,3, 4,4 -biphenyltetra-carboxylic dianhydride (PPDA) with 3,3 -dimethyl-4,4 -diaminobiphenyl. Solvents used for the one-step synthesis to the fully cyclized imide structure were phenol, p-chlorophenol, m-cresol, p-cresol and 2,4-dicholorophenol. The polycondensations were performed at 180°C for 2h with a monomer concentration of 6% by weight and p-hydroxybenzoic acid used as a catalytic accelerator. A maximum of 50 mol % of PMDA could be used before the copolymer precipitated from solution. Reconstituted copolymers as isotropic dopes (8-10% by weight) in p-chlorophenol were dry-jet wet spun between 80 and 100 °C [62]. 

C. Dileo, and I. Tommasi, Enzymic synthesis of 4-hydroxybenzoic acid from phenol and carbon dioxide the first example of a biotechnological application of a carboxylase enzyme, Tetrahedron 1998, 54, 8841-8846. 

Dankwardt SM, Phan TM, Krstenansky JL, Combinatorial synthesis of small-molecule libraries using 3-amino-5-hydroxybenzoic acid, Mol. Diversity, 1 113-20, 1996. 

Initial modification of the acyl side chain yielded FR131535.11 The synthesis of this novel echinocandin-like lipopeptide is outlined in Figure 15.5. The palmitoyl group was removed from FR901379 by treating it with acylase from Actinoplanes utahensis, which yielded FR179642. A new acyl side chain was prepared starting with 1-bromooctane and 4-hydroxybenzoic acid. 

Furans with suitable substituents in the 2-position can also be converted into phenols. These can be transformed into a 1,4-dicarbonyl system by 2,5 oxidation and ring opening. This system can then condense intramolecularly into a six-membered ring.333 334 The synthesis of m-hydroxybenzoic acid in 26% yield from furfuryl chloride288 is an example of this ... 

Zinc chloride-Phosphoryl chloride, ZnClj-POCla. This combination is used for the synthesis of hydroxyxanthones from an o-hydroxybenzoic acid and a phenol and of 4-hydroxycoumarins from a phenol and a malonic acid. Neither reagent is effective alone,... 

Chorismate is converted to prephenate (the precursor of phenylalanine and tyrosine) and anthranilate (the precursor of tryptophan). (Chorismate can also be converted to 4-hydroxybenzoic acid, the precursor of the ubiquinones. 4-Hydroxyphenylpyruvate is also a precursor in the synthesis of plastoquinone and various tocopherols.) PRPP is an abbreviation for phosphoribosylpyrophosphate. 

Nicolaou [57] has reported the synthesis of a dodecasaccharide employing a p-hydroxybenzoic acid spacer group connected via a photo labile linker [3- (hydroxymethyl) -4-nitrophenol] to the resin (Scheme 20.16). Sugar mono- or oligomers... 

The carboxylation of hydroxyaromatic compounds in the form of alkaline salts (the Kolbe Schmitt reaction) is well known and applied in the synthesis of acids such as salicylic acid, para-hydroxybenzoic acid and orf/to-cresotinic acid. 

Juch, ibid. 26, 839 (1905) Brunner, Ann. 351, 321 (1907) Zeltner, Landau, Ger. pat. 258,887 Frdl. 11, 210 Dyson, Man mo/ of Organic Chemistry vol. 1 (London, 1950) p 614 by oxidstion of salicylic acid with potassium persulfate Ger, pat. 81,297 (to Schering AG) Frdl 4, 127 from p-hydroxyphenol Meyer, U.S. pat. 2,580,336 (1952 to Monsanto) from 5 -bromo -2 -hydroxybenzoic acid Lowen -thal. Pepper, J. Am. Chem. See. 72, 3292 (1950) by Kolbe synthesis Clemens, U.S. pet. 2,816,137 (1957 to Eastman Kodak). Metabolic product of Pertici/fium patulum Tanen -baum, Bassett, Biochim. Biophys. Acta 28, 21 (1958) of Poty-porus tumulosus Cooke Crowden, Ralph, Amt, J. Chem. 14, 475 (1961). Biosynthesis Oaten back, Linnroth, Acta Chem. Scand. 16, 2298 (1962). 

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