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ChemicalBook CAS DataBase List 2-Bromo-3-methylthiophene

2-Bromo-3-methylthiophene synthesis

6synthesis methods
2-Bromo-3-methylthiophene synthesis: To a solution of glacial AcOH (100 mL), acetic anhydride (4.0 g, 0.039 mol), and 3-methylthiophene (9.82 g, 0.100 mol) as a stirred mixture was added NBS (19.6 g, 0.11 mol) in one portion with a slight exotherm to 44 oC. After 20 min the reaction mixture was poured onto ice, neutralized with sodium bisulfite and extracted with ether. The ether layer was washed with water and concentrated to give 11.3 g (64%) of 2-bromo-3-methylthiophene as a tan colored liquid in 88% purity by GC area % analysis: 1H NMR (CDCl3) d 7.1 (d, 1H, J=5.7 Hz), 6.7 (d, 1H, J=5.9 Hz), 2.2 (s, 3H).
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Yield:-

Reaction Conditions:

with acetic acid in chloroform;water;

Steps:

1 2-Bromo-3-Methylthiophene

Example 1 2-Bromo-3-Methylthiophene To a solution containing 600 ml of chloroform, 600 ml of acetic acid, and 98.0 g of 3-methylthiophene was added portionwise 188.0g of N-Bromosuccinimide with stirring. The addition was exothermic and the reaction mixture was kept below 35°C by means of an ice bath. After the addition was complete, the reaction was allowed to sit for 30 minutes at room temperature whereupon 1.2L of water was added. The organic layer was separated, washed with 600ml of water, followed by 600 ml of 1N NaOH, and finally 600 ml of water. The organic layer was dried over MgSO4, filtered, and the filtrate reduced to a tan oil. Fractional distillation afforded 128g of a yellow mobile oil boiling between 130°C and 170°C.

References:

EP308170,1989,A1

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