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ChemicalBook CAS DataBase List 5-Chloro-2-fluorobenzyl bromide
71916-91-1

5-Chloro-2-fluorobenzyl bromide synthesis

1synthesis methods
5-Chloro-2-fluorotoluene

452-66-4

5-Chloro-2-fluorobenzyl bromide

71916-91-1

General procedure for the synthesis of 5-chloro-2-fluorobenzyl bromide from 5-chloro-2-fluorotoluene: A: 5-Chloro-2-fluorotoluene (100 g, 692 mmol) was dissolved in ethyl acetate (300 ml) at 20 °C. To this solution N-bromosuccinimide (147.7 g, 830 mmol) and dibenzoyl peroxide (2 g, 8.25 mmol) were added sequentially. The reaction mixture was heated to 80 °C and stirred for 3 hours. Upon completion of the reaction, heptane (300 ml) was added and the mixture was cooled to 0 °C, at which time the succinimide precipitated. After filtration and washing with heptane, the residue was washed with water (1500 ml). The filtrate was concentrated to dryness under vacuum to give 162 g of the crude product 5-chloro-2-fluorobenzyl bromide. The crude product (141 g) was purified by vacuum distillation at 99 °C and 33 mbar to give the final 5-chloro-2-fluorobenzyl bromide (99 g, 75% yield). The purity of the product was analyzed by GC to be 87.1% (% area).1H-NMR (CDCl3) data: δ 4.44 (2H, d, CH2), 7.01 (1H, t, H3), 7.26 (1H, m, H4), 7.38 (1H, m, H6).

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Yield:71916-91-1 75%

Reaction Conditions:

with N-Bromosuccinimide;dibenzoyl peroxide in ethyl acetate at 20 - 80; for 3 h;

Steps:

6.A
A: 5-chloro-2-fluoro-benzylbromide5-Chloro-2-fluoro-toluene (100 g, 692 mmol) was dissolved in ethylactate (300 ml) at 20 0C. To this solution N-bromosuccinimide (147.7 g, 830 mmol) and dibenzoyl peroxide (2 g, 8.25 mmol) was added. The mixture was stirred at 80 0C for 3 hours.Heptane (300 ml) was added and the solution was cool to 0 °C whereupon succinimide precipitates. After filtration and washing with heptane, the residue was washed with water (1500 ml). The filtrate was concentrated in vacuo to dryness, yielding 162 grams of crude 5-chloro-2-fluoro-benzylbromide. Purification of the crude product (141 grams) was done by vacuum distillation at 99 0C and 33 mbar, this 5-chloro-2-fluoro-benzylbromide (99 grams, 75 %). Purity according to GC is 87.1 % a/a.1H-NMR (CDCI3): 4.44 (2H, d, CH2), 7.01 (1H, t, H3), 7.26 (1H, m, H4), 7.38 (1 H, m, H6)

References:

N.V. ORGANON WO2008/3460, 2008, A1 Location in patent:Page/Page column 23-24

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