0-Methylbenzyl acetate

A. o-Methylbenzyl acetate. A solution of 29.8 g. (0.20 mole) of 2-methylbenzyldimethylamine 2 and 32.7 g. (0.30 mole) of ethyl bromide in 40 ml. of absolute ethanol is placed in a 500-ml. round-bottomed flask fitted with a reflux condenser capped with a calcium chloride drying tube. The solution is heated under reflux on the steam bath for 1 hour then an additional 10.8 g. (0.10 mole) of ethyl bromide is added and the heating continued for an additional 3 hours. The solvent and residual ethyl bromide are removed at reduced pressure (water aspirator) while the flask is heated in a water bath kept at about 60° (Note 1). The oily residue is treated with about 300 ml. of absolute ether, and on scratching crystallization is induced. The product is collected on a Buchner funnel, washed with two 50-ml. portions of anhydrous ether, and dried in a vacuum desiccator. The yield of colorless 2-methylbenzylethyldimethylammonium bromide is 47.5-49.0 g. (92-95%) (Note 2). It is hygroscopic and should therefore not be exposed to moist air. 

B. o-Methylbenzyl alcohol. A solution of 5 g. (0.12 mole) of sodium hydroxide in 50 ml. of water is added to a solution of 16.4 g. (0.1 mole) of 2-methylbenzyl acetate (prepared as described above, part A) in 50 ml. of methanol contained in a 250-ml. round-bottomed flask fitted with a reflux condenser. The mixture is boiled under reflux for 2 hours, cooled, diluted with 50 ml. of water, and extracted with three 75-ml. portions of ether. The combined ether solutions are washed with 50 ml. of water and 50 ml. of saturated sodium chloride solution and dried over anhydrous sodium sulfate. The solvent is removed by distillation, finally at reduced pressure to remove the last traces of methyl alcohol, and the residue is dissolved in 50 ml. of boiling 30-60° petroleum ether. The colorless crystals obtained on cooling, finally in the ice bath, are collected by suction filtration, washed with a few milliliters of cold petroleum ether, and air-dried. Concentration of the mother liquors to 6-7 ml. and cooling gives an additional crop. The total yield of product melting between 33-34° and 35-36° is 11.6-11.8 g. (95-97%) (Note 7). 

A similar Te02/HBr catalyst has been used in acetic acid for the oxidation of propene at ca. 120 °C to propene oxide and propene glycol via 1,2-diacetoxypropane.361,362 However, this reaction gives lower yields because of side allylic oxidation reactions. Oxidation of toluene under similar conditions (Te02/LiBr, 160 °C) results in the formation of methylbenzyl acetate mixtures rather than benzyl acetate as observed with Se02/LiBr catalyst (equation 133).363... 

Methylbenzyl Acetate FEMA No. 3072 o-Tolyl Acetate 164.20/Ci0Hi2O2/ ch2oocch3 ch3 colorless liq/ sweet, nutty s—most fixed oils ss—prop glycol ins—gly 1 mL in 2 mL 70% ale remains clear on dilution... 

The ruthenium-catalyzed racemization of a-methylbenzyl alcohol was combined with an enzyme-catalyzed transesterification with lipase. Dinuclear ruthenium complex 64 effectively catalyzes the racemization of a-methylbenzyl alcohol and the combination of 64, p-chlorophenyl acetate, and enzyme N-435 in the reaction of racemic amethylbenzyl alcohol gave enantiomerically pure (R)-a-methylbenzyl acetate in the excellent yield (Eq. 12.26) [29]. 

---