Benzoic Acid → Phenethyl Benzoate

Participants

Reaction Conditions

Reaction Steps

A 2-L, 4-neck round bottom flask, fitted with a thermometer, mechanical stirrer, nitrogen inlet tube and Liebig condenser/receiving flask, was charged with 671.7 g (5.50 mol, 1.00 equiv) of benzoic acid, 806.3 g (6.60 mol, 1.20 equiv) of 2-phenylethyl alcohol, 5.30 g (0.43% w/w, 1.0 mol %) of methanesulfonic acid (MSA) and 1.25 g (0.1% w/w) of triisodecylphosphite (TDP). The system was heated gently with slow stirring (<50 rpm) until the benzoic acid dissolved. The air was removed with three cycles of evacuation/nitrogen fill using a mechanical vacuum pump (50–100 torr). The rate of stirring was increased to ca. 200 rpm, the nitrogen sparge was set at 0.2 scfh, and the reaction mixture was heated to 140° C. After a 1-h hold, the temperature was increased to 150° C. and held for 1 h. The temperature was increased to 160° C. and the nitrogen sparge was increased to 0.5 scfh. After a 1-h hold, the reaction mixture was cooled to room temperature and sampled for analysis. The acid number was 8.1 mg KOH/g (97.3% conversion of benzoic acid, corrected for MSA), the APHA color was 66, and the excess 2-phenylethyl alcohol was 7.9% by GLC. To the reaction mixture at 25° C. was added 213 g of 10% w/w aqueous sodium carbonate solution. The batch was heated to 50° C. and stirred for 15 min. The stirring was stopped and the batch was allowed to settle for 30 min. The bottom aqueous layer was removed from the flask with a pipette, and 2-phenylethyl alcohol was removed by vacuum distillation at 180–190° C. (20 torr) for 1 h with a nitrogen sweep of 0.5 scfh. The reaction mixture was cooled to ca. 70° C. and sampled for analysis. The residual 2-phenylethyl alcohol was 0.17% by GLC, the acid number was 0.10 mg KOH/g, and the APHA color was 95. Treatment with activated carbon and filtration as usual (see Example 1) gave 1100 g (88%) of 2-phenylethyl benzoate. The APHA color was 72, the acid number was 0.11 mg KOH/g, the saponification number was 242 mg KOH/g, the residual sulfur was <10 ppm, and the residual phosphorous was <10 ppm.

Provenance & Evidence