Chemfiles Volume 6 Article 2

Diazomethane is an extremely versatile reagent for the preparation of both C–O and C–C bonds.1 It is one of the most common methylating reagents for carboxylic acids and has found extensive application in the alkylation of phenols, enols, and heteroatoms, such as nitrogen and sulfur. Diazomethane has also been used in cycloalkanone ring expansion, preparation of α-diazo ketones from carboxylic acid halides, and pyrazoline formation (Scheme 37).

Scheme 37

Due to the toxicity and unstable nature of diazomethane, all reactions involving its preparation and use should be carried out using proper precautions.2 Sigma-Aldrich is pleased to offer Diazald® as the preferred diazomethane precursor, as well as a variety of specialized glassware for safe generation of this versatile reagent. Diazomethane can be conveniently prepared and purified as a solution in a variety of scales (1 to 300 mmol), depending on the glassware kit chosen.

back to top


  1. For thorough reviews, see: (a) Hopps, H. B. et al. Aldrichimica Acta 1970, 3, 9; (b) Black, T. H. et al. Aldrichimica Acta 1983, 16, 3.
  2. Please view our Aldrich Technical Bulletin, AL-180, at: www.sigmaaldrich.com/Brands/Aldrich/Tech_Bulletins.html

back to top

Related Links