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TCI Practical Example: Bromination of an Alkyl Alcohol through the Appel Reaction

We are proud to introduce the bromination reaction of the hydroxy group of 2-phenethyl alcohol using carbon tetrabromide and triphenylphosphine.

Used Chemicals

• 2-Phenylethyl Alcohol [P0084]
• Carbon Tetrabromide [T0038]
• Triphenylphosphine [T0519]
• Dichloromethane

Procedure

A solution of triphenylphosphine (0.644 g, 2.46 mmol) in dichloromethane (3.3 mL) was added to a mixture of 2-phenylethyl alcohol (0.196 mL, 1.64 mmol) and carbon tetrabromide (0.652 g, 1.96 mmol) in dichloromethane (8.2 mL) at 0 ºC. The reaction mixture was stirred at room temperature for 1 hour and concentrated under reduced pressure. The given crude product was purified by silica gel column chromatography (hexane:ethyl acetate = 7:3) to afford (2-bromoethyl)benzene (0.290 g, 96% yield) as a colorless liquid.

Experimenter’s Comments

The reaction mixture was monitored by TLC (hexane:ethyl acetate = 4:1, Rf = 0.7).

Analytical Data

¹H NMR (400 MHz, CDCl₃); δ 7.36-7.20 (m, 5H), 3.78 (t, J = 11.2 Hz, 2H), 3.17 (t, J = 11.2 Hz, 2H).

¹³C NMR (101 MHz, CDCl₃); δ 138.9, 128.6, 128.5, 126.9, 39.4, 32.9.

Lead Reference

• Hexabromoacetone and ethyl tribromoacetate: a highly efficient reagent for bromination of alcohol
• P. Tongkate, W. Pluempanupat, W. Chavasiri, Tetrahedron Lett. 2008, 49, 1146.