Diazald

Diazald (N-methyl-N-nitroso-p-toluenesulfonamide) is used as a relatively safe and easily handled precursor to diazomethane, which is toxic and unstable.[2] 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'-nitro-N-nitrosoguanidine, which are less thermally stable and more toxic and mutagenic, respectively.

Diazald
Names
IUPAC name
N-Methyl-N-nitroso-p-toluenesulfonamide
Other names
N-Methyl-N-nitroso-4-methylbenzenesulfonamide; N-Methyl-N-nitroso-p-toluenesulphonamide; N-Methyl-N-nitroso-4-methylbenzenesulphonamide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.001.139
EC Number
  • 201-252-6
MeSH C418734
UNII
Properties
C8H10N2O3S
Molar mass 214.24 g·mol−1
Appearance Light yellow solid
Melting point 61–62 °C (142–144 °F; 334–335 K)
Hazards
Main hazards Skin sensitiser, irritant, explosive[1]
Safety data sheet External MSDS
NFPA 704 (fire diamond)
Flammability code 0: Will not burn. E.g. waterHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformReactivity code 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g. hydrogen peroxideSpecial hazards (white): no code
0
2
3
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Upon the addition of a base such as sodium hydroxide or potassium hydroxide 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[3]), 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 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.[4]

References
  1. External MSDS, Sigma Aldrich
  2. Diazald in Chemical Synthesis, Sigma Aldrich
  3. "Diazomethane". www.orgsyn.org. Retrieved 2018-07-27.
  4. Zhu, Xiao-Qing; Hao, Wei-Fang; Tang, Hui; Wang, Chun-Hua; Cheng, Jin-Pei (March 2005). "Determination of N−NO Bond Dissociation Energies ofN-Methyl-N-nitrosobenzenesulfonamides in Acetonitrile and Application in the Mechanism Analyses on NO Transfer". Journal of the American Chemical Society. 127 (8): 2696–2708. doi:10.1021/ja0443676. ISSN 0002-7863. PMID 15725027.
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