Article · Wikipedia archive · Last revised Jun 24, 2026

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. Since its introduction in 1954, 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.

Last revised
Jun 24, 2026
Read time
≈ 2 min
Length
469 w
Citations
9
Source
Wikipedia ↗
Diazald
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Names
Preferred IUPAC name
N,4-Dimethyl-N-nitrosobenzene-1-sulfonamide
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
  • InChI=1S/C8H10N2O3S/c1-7-3-5-8(6-4-7)14(12,13)10(2)9-11/h3-6H,1-2H3
    Key: FFKZOUIEAHOBHW-UHFFFAOYSA-N
  • InChI=1/C8H10N2O3S/c1-7-3-5-8(6-4-7)14(12,13)10(2)9-11/h3-6H,1-2H3
    Key: FFKZOUIEAHOBHW-UHFFFAOYAJ
  • Cc1ccc(cc1)S(=O)(=O)N(C)N=O
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
Occupational safety and health (OHS/OSH):
Main hazards
 Skin sensitiser, irritant, explosive1
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 0: Will not burn. E.g. waterInstability 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
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2
0
3
Safety data sheet (SDS) External MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

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 Since its introduction in 1954,3 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.

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),4 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:5a

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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.8

Notes

Notes

  1. Black (1983) and Brückner (2010) instead suggest a mechanism involving a 1,3-shift to form a toluenesulfonyl diazoate, followed by 1,3-elimination.67
References

References

  1. External MSDS, Sigma Aldrich
  2. "Diazald in Chemical Synthesis". Sigma-Aldrich. Archived from the original on 8 December 2008.
  3. de Boer, Th. J. [at Wikidata]; Backer, H. J. [in Dutch] (January 1954). "A new method for the preparation of diazomethane". Recueil des Travaux Chimiques des Pays-Bas. 73 (3): 229–234. doi:10.1002/recl.19540730308.
  4. de Boer, Th. J.; Backer, H. J. (1956). "Diazomethane". Org. Synth. 36: 16. doi:10.15227/orgsyn.036.0016.
  5. de Boer, Th. J. [at Wikidata]; Backer, H. J. [in Dutch] (January 1954). "Mechanism of the alkaline decomposition of sulphonylnitrosamides: (IInd communication on sulphonylnitrosamides)". Recueil des Travaux Chimiques des Pays-Bas. 73 (7): 582–588. doi:10.1002/recl.19540730711.
  6. Black, T. Howard (1983). "The Preparation and Reactions of Diazomethane" (PDF). Aldrichimica Acta. 16 (1): 3–10.
  7. Brückner, Reinhard [in German] (2010). Harmata, Michael (ed.). Organic Mechanisms: Reactions, Stereochemistry and Synthesis (PDF). Berlin, Heidelberg: Springer Berlin Heidelberg. pp. 677–678. ISBN 9783642036507.
  8. Zhu, Xiao-Qing; Hao, Wei-Fang; Tang, Hui; Wang, Chun-Hua; Cheng, Jin-Pei (March 2005). "Determination of N−NO Bond Dissociation Energies of N-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.