Hydroxybenzyl alcohols

To a solution of 24.4 g. (0.20 mole) of salicylaldehyde in 100 ml, of 95% ethanol are added 0.5 ml. of 2 M aqueous ferrous chloride solution and 0.1725 g. of platinum oxide catalyst [Org. Syntheses Coll. Vol. 1, 463 (1941)]. The mixture is shaken under a pressure of 3 atm. of hydrogen in a low-pressure hydrogenation apparatus [Org. Syntheses Coll. Vol. 1, 61 (1941)]. The absorption of hydrogen is complete in 1 hour. To the mixture is added 0.4 ml. of 1 N aqueous sodium hydroxide solution, and the catalyst is recovered by filtration of the mixture. The solvent is removed from the filtrate by evaporation under vacuum, and the solid residue is recrystallized from 150 ml. of hot benzene. There is obtained a 92% yield of o-hydroxybenzyl alcohol as white crystals, m.p. 84.5-85°. 

The substituted benzyl alcohols listed below are prepared in a similar manner from the corresponding aldehydes in the yield indicated vanillyl alcohol, m.p. 113-114°, recrystallized from benzene, 95% anisyl alcohol, b.p. 127-130°/8 mm., 92% piperonyl alcohol, m.p. 52-53°, recrystallized from a mixture of ether and petroleum ether, 91% p-chlorobenzyl alcohol, m.p. 71-72.5°, recrystallized from ben-zene-ligroin mixture, 92% o-chlorobenzyl alcohol, m.p. 64 65°, 96% p-bromobenzyl alcohol, m.p. 76-76.5°, 96%. 

A solution of 20 g. (0.17 mole) of acetophenone and 9.5 g. (0.22 mole) of freshly distilled acetaldehyde in 100 ml. of methanol is cooled, and 2 drops of 50% aqueous potassium hydroxide solution is added. The mixture is allowed to stand for 1 day, and the precipitated red oil is separated, dried over calcium chloride, and distilled under vacuum. There is obtained 13.8 g. (47%) of /3-hydroxy-n-butyrophe-none boiling at 150-152°/12 mm. 

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Industrial electrochemical reduction processes exist for the conversion of 3-hydroxybenzoic acid to 3-hydroxybenzyl alcohol and 4-nitroben-zoic acid to 4-aminobenzoic acid. How may these processes be carried out Compare these processes in terms of the Principles of Green Chemistry with alternative non-electrochemical methods. 

Photolytic. Photolysis of permethrin in aqueous solutions containing various solvents (acetone, hexane, and methanol) under UV light (1 >290 nm) or on soil in natural sunlight initially resulted in the isomerization of the cyclopropane moiety and ester cleavage. Photolysis products identified were 3-phenoxybenzyldimethyl acrylate, 3-phenoxybenzaldehyde, 3-phenoxybenzoic acid, mono-chlorovinyl acids, cis- and fra/is-dichlorovinyl acids, benzoic acid, 3-hydroxybenzoic acid, 3-hydroxybenzyl alcohol, benzyl alcohol, benzaldehyde, 3-hydroxybenzaldehyde, and 3-hydroxybenzoic acid (Holmstead et ah, 1978). 

The oxidation of m-cresol was carried out in Parr autoclave at 353 K using a 3 1 mixture of H2O and acetonitrile as solvent and Sn-silicalites with Si/Sn ratio of 70 as catalysts. A slightly higher efficiency for H2O2 is seen with Sn-ZSM-12 sample (Table 4). The dihydroxylated products, viz., 2-methylhydroquinone and 4-methylcatechol are found to be in excess over the products of side chain oxidation, viz., 3-hydroxybenzyl alcohol and the aldehyde in the product mkture. The aromatic hydroxylation on Sn-silicalites may follow an ionic mechanism as both the -CH3 and -OH groups in m-cresol are favourably placed for electrophilic substitution reaction. Interestingly, the product distribution on all the three Sn-molecular sieves is almost similar. This shows that in all the three types, the Sn ions are dispersed uniformly and possess identical catalytic property due to similar environment around them. 

C 3-Hydroxybenzyl alcohol 3-Hydroxy benzoic acid Mitsui Taatsu 100... 

Oxidation of substituted benzyl alcohols to the corresponding aldehydes has been patented [102-107]. Oxidation of 3-hydroxybenzyl alcohol in alkaline solution over Pt- and/or Pd-type catalysts yielded 3-hydroxybenzaldehyde with high selectivity [103]. An alcohol and a tertiary ammonium salt were used to control formation of by-product 3-hydroxybenzoic acid. Oxidation of 2-hydroxybenzyl alcohol in aqueous basic medium in the presence of Pt and B and Bi derivatives (H3BO3 and Bi203) gave 97 % of the corresponding aldehyde (salicylaldehyde)... 

Benzyl alcohol 4-Methylbenzyl alcohol 4-Fluorobenzyl alcohol 4-Chlorobenzyl alcohol 4-Bromobenzyl alcohol 4-Nitrobenzyl alcohol 4-Methoxybenzyl alcohol 3,5-Dimethoxybenzyl alcohol 3-Methoxybaizyl alcohol 3-Hydroxybenzyl alcohol 33 Pihydroxybenzyl alcohol... 

Formylguaiacol, in D-10108 A-Formylharappamine, in H-10003 2-Formyl-3-hydroxybenzoic acid, F-20024 2-Formyl-6-hydroxybenzoic acid, F-20025 2-Formvl-3-hydroxybenzyl alcohol, see... 

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