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Diazald (''N''-methyl-''N''-nitroso-''p''-toluenesulfonamide) is used as a relatively safe and easily handled precursor to 
Like other
diazomethane
Diazomethane is the chemical compound CH2N2, discovered by German chemist Hans von Pechmann in 1894. It is the simplest diazo compound. In the pure form at room temperature, it is an extremely sensitive explosive yellow gas; thus, it is almost u ...
, which is toxic and unstable. Diazald has become the favored commercially available precursor for the synthesis of diazomethane, compared to reagents like ''N''-methyl''-N-''nitrosourea and ''N-''methyl-''N''sodium hydroxide
Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions .
Sodium hydroxide is a highly caustic base and alkali ...
or potassium hydroxide
Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash.
Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which exp ...
and mild heating (65–70 °C) in a mixture of water, diethyl ether, and a high boiling polar cosolvent (e.g., diethylene glycol monomethyl ether
2-(2-Methoxyethoxy)ethanol, also known under trade names Methyl carbitol, is an industrial solvent and is also commonly used as a fuel system icing inhibitor (FSII) in jet fuels. It is a clear, colorless, hygroscopic liquid. Structurally it is an ...
), the ''N-''nitrososulfonamide undergoes successive elimination reactions to produce diazomethane (which is codistilled as an ethereal solution) as well as a ''p''-toluenesulfonate salt as a byproduct, according to the following mechanism:
Like other nitroso
In organic chemistry, nitroso refers to a functional group in which the nitric oxide () group is attached to an organic moiety. As such, various nitroso groups can be categorized as ''C''-nitroso compounds (e.g., nitrosoalkanes; ), ''S''-nitroso ...
compounds, it is thermally sensitive, as a result of its weak N–NO bond whose bond dissociation energy was measured to be 33.4 kcal/mol.
References
{{reflist Sulfonamides Nitroso compounds Alkyl-substituted benzenes