p-Toluenesulfonic acid → Methyl 3-phenoxypropionate

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Reaction Steps

To demonstrate the methyl ester, as well as the ethyl ester, may be used to make members of composition 7, we illustrate the preparation of the corresponding methyl ester of composition 7 in which the Et group is replaced by Me and X is O. A solution of 3-phenoxypropionic acid (10.0 g, 0.060 mol) and p-toluenesulfonic acid (0.6 g, 0.0033 mol) in methanol (250 mL) was heated at reflux through 3 Å molecular sieve for 36 hours under N2 in a flask equipped with a Soxhlet extractor and a condenser. The solution was allowed to cool to room temperature and then was concentrated to a volume of 50 mL, diluted with water (50 mL), and extracted with ether (2×75 mL). The combined organic layers were washed with 5% aqeuous NaHCO3 (75 mL), H2O (75 mL), and brine (75 mL). After drying (Na2SO4) the solution, the solvent was removed (vacuum). Vacuum distillation gave 9.45 grams (87.1%) of the title ester as a colorless liquid: by 85°-87° C./0.1 mm (literature reports 85° C./0.4 mm; see C. E. Rehberg and M. D. Dixon [J. Am. Chem. Soc. 72, 2205 [1972]): IR (neat) 1740-1750 cm-1 (C=O); 1H NMR (DCCl3) δ 2.78 [s, 2H, CH2CO2CH3 ], 3.70 [s, 3H, OCH3 ], 4.23 [2H, OCH], 6.84-7.02 and 7.18-7.35 [m, 5H, ArH]; 13C NMR (DCCl3) ppm 34.3 [H2CCO2 ], 51.7 [CH3 ], 63.2 [Ar--OCH2 ]; Ar--C [114.5, 120.8, 129.2, 158.3, 171.1].

Provenance & Evidence