Diazomethane


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diazomethane

[dī¦a·zō′me‚thān]
(organic chemistry)
CH2N2 A poisonous gas used in organic synthesis to methylate compounds.

Diazomethane

 

the very simple acyclic diazo compound CH2N2; a highly toxic and explosive yellowish gas with an unpleasant odor. Melting point, -145°C; boiling point, -23° C. The structure of diazomethane can be represented by the following formulas: Diazomethane.

Diazomethane is usually produced by treating nitrosomethylurea (1) or nitrosomethylurethane (2) with an alkali:

Diazomethane may react with or without the liberation of nitrogen. The most important reactions of diazomethane involve the liberation of N2: the generation of carbene upon pyrolysis or photolysis of diazomethane or under the catalytic action of powdered copper:

(3) CH2N2→:CH2+N2

reactions with acids, phenols, and alcohols, with the formation of corresponding methyl ethers and esters, such as

(4) CH3COOH + CH2N2→CH3COOCH3 + N2

and interaction with halogens and halides of other elements:

Diazomethane

Diazomethane reacts without the liberation of nitrogen with such compounds as the acid halides of carboxylic acids, resulting in the production of diazoketones. When the diazoketones decompose in the presence of water, alcohols, or amines and a catalyst (Ag2O), regrouping takes place, resulting in the formation of an acid (its ester or amide) with one more carbon atom than in the initial acid chloride (the Arndt-Eistert reaction):

Diazomethane

The synthesis of carboxylic acids is one of the most important applications of diazomethane; it is also used extensively as a methylizing agent.

B. L. DIATKIN

References in periodicals archive ?
We prepared diazomethane from N-methyl-N-nitrosoguanidine following Aldrich Technical Information Bulletin AL 121 (23).
The extracted analytes are then derivatized, with the most popular derivatizing agents being PFBBr and diazomethane. The derivatized analytes are analyzed using GC-electron capture detection, GC-MS (Koch and Angerer 2001), and GC-MS/MS (Hill et al.
The phenolic compounds were isolated after the extraction from the plasma by using potassium hydroxide (0.5 M in 50% ethanol) and were derivatized to their corresponding methyl ethers by addition of ethereal diazomethane (0.5 mL, 3 hr at 4-8[degrees]C) before cleanup and analysis (Hovander et al.
To methylate the hydroxyl group, the samples were treated with an excess of a diazomethane solution at room temperature for 3 hr, and the solvent was removed by blowing it down to near dryness.
They are based on chlorophenol liquid-liquid or solid phase extraction followed by derivatization with diazomethane, methylene chloride or pentafluorobenzyl bromide and GC-FID, GC-ECD, or GC-MS detection.
During this time he taught everyone in the organic laboratories to make diazomethane from 1-methyl-3-nitro-1-nitrosoguanidine (MNNG), a reaction discovered by McKay.
Fractions 10-14 (520 mg) eluted using EtOAc 100% were methylated with diazomethane and further chromatographed on a silica gel column (10 g, 1.5 X 60 cm) to afford frs.
The OH-PCBs in the sample extracts and calibration standards were methylated by adding diazomethane that was synthesized as described elsewhere (Sandau 2000).
TMS-DM is an ideal derivatization reagent and a convenient alternative source of diazomethane, which is known to be safer to handle and more stable [40,44].
A 15 ml yellow dimethylether solution of diazomethane, ready for use and prepared by adding alcoholic solution of KOH to 300 mg of Diazald, was poured into 0.5 g of polymer while stirring.
Although the parent compound, diazomethane, was reactive, the TMS-substituted ylide gave significantly higher yields (>98% vs.