Bromine

General Information:

Structure:

CAS Number: 7726-95-6

Molecular Weight: 159.81 g/mol

Appearance: Brown/red fuming liquid

Chemical Formula: Br2

Melting Point: -7.2 C

Boiling Point: 58.8 C

Density: 3.119 g/mL

Bromine (Br2) is typically used in bromination reactions. As a fuming brown/red liquid, bromine can be difficult to handle on small or large scale. A common, easy to handle alternative to bromine is N-Bromosuccinimide (NBS).

Common Uses:

Reagent in SEAr (Electrophilic Aromatic Substitution) brominations

Procedure excerpt:

To a solution of the SM (80 g, 0.27 mol) in CHCl3 (1 L) at 10-15 C was added dropwise a solution of Br2 (16 mL, 0.31 mol) in CHCl3 (100 mL). The reaction was stirred . . .

[full procedure]

Reagent in brominations at alpha positions

Procedure excerpt:

To a mixture of the SM (2.4 g, 13.86 mmol) in AcOH (50 mL) was added Br2 (0.80 mL, 15.53 mmol). The mixture was stirred at RT for 3 days, after which time . . .

[full procedure]

Reagent in the conversion of alcohols to bromides via Appel reactions

Procedure excerpt:

To a solution of PPh3 (26.2 g, 0.10 mol) in ACN (50 mL) at 0 C was added dropwise a solution of Br2 (5.13 mL, 0.10 mol) in ACN (30 mL). The SM (5.1 g, 0.050 mol) was . . .

[full procedure]

Safety:

Bromine is a very toxic and corrosive volatile liquid. Skin contact can cause painful burns and blisters.

References:

1) Patent Referenc: WO2014177977, page 64, (6.0 MB)

2) Patent Reference: WO2011017578, page 154, (8.3 MB)

3) Patent Reference: WO2015129926, page 100, (21.5 MB)

4) Wikipedia: Bromine (link)

5) Burke, S. D.; Danheiser, R. L.; Handbook of Reagents for Organic Synthesis, Oxidizing and Reducing Agents