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Formation of benzyl azide from benzyl bromide; Benzyl azide

SyntheticPage 408
DOI: 10.1039/SP408
Submitted May 06, 2010, published May 06, 2010
Suzanne Elizabeth Howson (, Peter Scott (
A contribution from Scott group, Warwick University

			Reaction Scheme: Formation of <span id="csm1276782412706" class="csm-chemical-name" title="benzyl azide">benzyl azide</span> from <span id="csm1276782310388" class="csm-chemical-name" title="benzyl bromide">benzyl bromide</span>

Chemicals Used

Benzyl bromide
Dimethyl sulfoxide (DMSO)
Sodium azide
Water (distilled)
Diethyl ether
Sodium sulfate


Benzyl bromide (2.0 ml, 16.84 mmol, 1.0 eq.) was dissolved in DMSO (40 ml). Sodium azide (1.64 g, 25.26 mmol, 1.5 eq.) was added as a solid and the reaction was stirred overnight at ambient temperature. Water (75 ml) was added slowly (exothermic) before extracting the product into diethyl ether (3 × 150 ml). The combined diethyl ether layers were washed with brine (2 × 150 ml), dried over sodium sulfate and the solvent removed to leave a clear oil. Yield = 1.63 g, 12.24 mmol, 73%.

Author's Comments

Suitable precautions should be taken in the synthesis of organic azides as they are all potentially explosive, and particularly so where the C/N ratio or similar calculation indicates that this is likely. While you should do your own research on this, the following references may be useful:


1H NMR (400 MHz, 298 K, CDCl3) 7.42-7.32 (5H, m, Ph), 4.35 (2H, s, CH2).

 13C{1H} NMR (100 MHz, 298 K, CDCl3) 135.4 (Ph), 128.9 (Ph), 128.3 (Ph), 128.2 (Ph), 54.8 (CH2).

 MS (EI/CI) m/z 105.1 [M-2N]+.

 IR cm-1: 2090 s, 1497 w, 1455 m, 1253 m, 876 w, 735 m, 696 s.

 Elemental Analysis found (Calculated for C7H7N3) % C 63.53 (63.14), H 5.72 (5.30), N 31.34 (31.56).

Lead Reference

E. J. O'Neil, K. M. DiVittorio and B. D. Smith, Org. Lett., 2007, 9, 199-202 (General Procedure for the synthesis of azides)

Supplementary Information

Click to open Interactive 1H NMR
Click to open Interactive 13C NMR
1H NMR (1H Benzyl Azide.jcamp)
13C NMR (13C benzyl azide.jcamp)

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Keywords: alkyl/alkenyl/aryl halides, Azide, nucleophilic, substitution

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