Para-anisic acid

The dealuminated Y(30) zeolite efficiently promotes the benzoyla-tion of 2-butylbenzofuran with para-anisoyl chloride or para-anisic acid the reaction is performed at 180°C in 1,2-dichlorobenzene (Table 4.6), and leads to the three acylated isomers 15,16, and 17 with a good initial selectivity in the 3-acylated derivative 15. The selectivity decreases with time due to the consecutive deacylation of this compound, followed by a reacylation that favors the formation of the other two isomers (mainly, the 6-acylated one). As expected, lower activity is observed when the carboxylic acid is utilized as acylating agent. 

Table 4.6 Comparison of selectivity in the benzoylation of 2-butylbenzofuran with parfl-anisoyl chloride or para-anisic acid in the presence of Y zeolite...

FIGURE 8.38 Mass spectrum of para-anisic acid. 

Aromatic carboxylic acids produce intense molecular ion peaks. The most important fragmentation pathway involves loss of OH to form the CeHsC O" (miz = 105), followed by loss of CO to form the ion (mIz = 77). In the mass spectrum of para-anisic acid (Fig. 8.71), loss of OH gives rise to a peak at miz =135. Further loss of CO from this ion gives rise to a peak at miz =107. Benzoic acids bearing ortho alkyl, hydroxy, or amino substituents undergo loss of water through a rearrangement reaction similar to that observed for orffto-substituted benzoate esters, as illustrated at the end of Section 8.8R. 

Para-cresol methyl ether occurs naturally in oil of ylang-ylang and similar flower oils. It is also prepared synthetically, and forms a useful artificial perfume for compound flower odours. It is a liquid boiling at 175°, and, as stated above, yields anisic acid on oxidation. 

Anisic Acid.—derivative of para-hydroxy benzoic acid is the COOH (i)... 

Para-anisic aldehyde and p-anisic alcohol are two important p-cresol derivatives which have provided critical feedstocks for some of the important bulk drugs. Trimethoprim made from 3,4,5-trimethoxybenzaldehyde is another example. p-Cresol has already replaced gallic acid as the preferred starting material for 3,4,5-trimethoxy benzaldehyde. As more R D work is undertaken, there will no doubt emerge more finished pharmaceutical items not only from p-cresol but also from o-cresol and m-cresol. Growth of meZo-cresol has indeed been remarkable after the process was commercialized for... 

Solubility of Ortho Hydroxy Benzoic Acid (Salicylic Acid), Meta Hydroxy Benzoic Acid, and Para Hydroxy Benzoic Acm (Anisic Acid) in Water, Benzene, etc. (See also pp. 38 and 274.)... 

Salicylic acid is orthohydroxybenzoic acid. Metahydroxybenzoic acid was discovered by B. W. Gerland by the action of nitrous acid on meta-amino-benzoic acid, parahydroxybenzoic acid by C. Saytzeff by heating anisic acid (methylparahydroxybenzoic acid) with hydriodic acid — a precursor of Zeisel s method (see p. 871), and G. Fischer from para-aminobenzoic acid, which he discovered by the action of ammonium sulphide on paranitrobenzoic acid. Kolbe obtained the para-compound by passing carbon dioxide over potassium phenoxide at i7o°-2io° (sodium phenoxide gives only a small yield). 

The effect of para-substituents on the rate of exchange of benzoic acid was examined by Bender etal. (1956). Small differences were found in the rates of exchange of m- and p-chlorobenzoic, -anisic, p-toluic, mesitoic and benzoic acids in acid solution (see Table 7). No simple correlation between rates and electronic effects of the substituents could be found. 

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