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Benzoylation of a primary alcohol to give a benzoate ester; But-3-enyl benzoate

SyntheticPage 109
DOI: 10.1039/SP109
Submitted Aug 21, 2001, published Aug 21, 2001
Jonathan Wilden (jonathan_wilden@hotmail.com)
A contribution from Caddick, Sussex


			Reaction Scheme: Benzoylation of a primary alcohol to give a benzoate ester

Chemicals Used

But-3-ene-1-ol (Aldrich),
4-Dimethylaminopyridine (Avocado),
Triethylamine (Avocado),
Benzoic anhydride.

Procedure

But-3-ene-1-ol (3.0 g, 42 mmol) was dissolved in dichloromethane (100 mL) and triethylamine (7.6 mL, 5.6 g, 55 mmol) was added followed by DMAP (50 mg). Benzoic anhydride (12.4 g, 55 mmol) was added and the resulting yellow solution allowed to stir for 6 hours after which time dilute HCl (2 M, 100 mL) was added. The organic phase was separated and washed with a further two portions of HCl (2 x 100 mL) and water (2 x 100 mL). The organic phase was separated, dried (MgSO4), filtered and concentrated in vacuo. The crude product was purified by distillation (20 mm, bp. 82-84 oC) to yield the pure benzoate ester as a clear oil (4.8 g, 28 mmol, 65%).

Author's Comments

We have performed this reaction twice and on a scale of 3-5 g of the alcohol. The reaction is not particularly sensitive to air, moisture etc. The addition of DMAP however accelerates the reaction significantly. Efficient cooling must therefore be used on the addition of DMAP to prevent overheating.

Data

1H NMR (300 MHz, CDCl3) 8.05 (2H, br. d), 7.56 (1H, br. t), 7.44 (2H, br. t), 5.88 (1H, app. ddt), 5.17 (1H, d), 5.12 (1H, d), 4.37 (2H, t), 2.53 (2H, app. q).

Lead Reference

Ramnauth, J.; Lee-Ruff, E.; Can.J.Chem., 77, 1999, 1245.

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Keywords: ester, benzoylation, anhydride, 109