Chemistry: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.[1] Since its introduction in 1954,[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.
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:[4][lower-alpha 1]
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.[7]
Notes
References
- ↑ "Diazald in Chemical Synthesis". Sigma-Aldrich. http://www.sigmaaldrich.com/chemistry/chemical-synthesis/technology-spotlights/diazald.html.
- ↑ de Boer, Th. J.; Backer, H. J. (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.
- ↑ de Boer, Th. J.; Backer, H. J. (1956). "Diazomethane". Org. Synth. 36: 16. doi:10.15227/orgsyn.036.0016. http://www.orgsyn.org/demo.aspx?prep=CV4P0250.
- ↑ de Boer, Th. J.; Backer, H. J. (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.
- ↑ Black, T. Howard (1983). "The Preparation and Reactions of Diazomethane". Aldrichimica Acta 16 (1): 3–10. https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/marketing/global/documents/187/633/acta-vol16.pdf#page=4.
- ↑ Brückner, Reinhard (2010). Organic Mechanisms: Reactions, Stereochemistry and Synthesis. Berlin, Heidelberg: Springer Berlin Heidelberg. pp. 677–678. ISBN 9783642036507. http://ndl.ethernet.edu.et/bitstream/123456789/63842/1/2010_Book_OrganicMechanisms.pdf#page=697.
- ↑ 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" (in en). Journal of the American Chemical Society 127 (8): 2696–2708. doi:10.1021/ja0443676. ISSN 0002-7863. PMID 15725027.
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