4.4 General procedure for the preparation of ethyl 3,3,3-trifluoropropionate:
(1) To a stirred suspension of potassium ethoxide (KOEt, 5.0 g, 59.4 mmol) in ether (Et2O, 200 mL), a solution of 2,2,3-tribromo-1,1,1-trifluoropropane (7, 6.0 g, 17.9 mmol) in ether (Et2O, 50 mL) was slowly added dropwise. The reaction mixture was stirred at room temperature for 15 min. Subsequently, the reaction was quenched with 1 M aqueous hydrochloric acid (50 mL) and stirring was continued for 30 min. The aqueous layer was separated and extracted with ether (50 mL × 3) and the combined organic phases were washed with brine (40 mL) and dried with anhydrous magnesium sulfate (MgSO4). The solvent was removed by concentration under reduced pressure to give the crude product. Purification of the crude product by distillation afforded ethyl 3,3,3-trifluoropropionate (1, 2.0 g, 72%) as a colorless oil with a boiling point of 106°C (760 mmHg).
Product characterization data:
IR (pure): 2989, 1747, 1384, 1360, 1267, 1216, 1110, 1026, 929, 836, 755, 653 cm-1.
1H NMR (400 MHz, CDCl3): δ 4.24 (q, J = 7.2 Hz, 2H), 3.17 (q, J = 10.1 Hz, 2H), 1.30 (t, J = 7.2 Hz, 3H).
13C NMR (100 MHz, CDCl3): δ 164.1 (q, JCF = 4.1 Hz, 1C), 123.4 (q, JCF = 274.5 Hz, 1C), 61.7 (1C), 39.5 (q, JCF = 30.8 Hz, 1C), 13.8 (1C).
19F NMR (376 MHz, CDCl3): δ -64.8 (t, JHF = 10.1 Hz, 3F).
EI-MS m/z (relative abundance): 156 [M]+ (2.4), 141 [M-Me]+ (1.4), 129 [M+2H-Et]+ (8.2), 111 [M-OEt]+ (100), 91 [CF2CHCO]+ (12.9), 83 [CF3CH2]+ (15.7), 69 [CF3]+ (7.5) , 45 [EtO]+ (41.4).
