Nitrosation of Cyanamide: Preparation and Properties of the Elusive E‐ and Z‐N'‐Cyanodiazohydroxides

• Published in: European journal of organic chemistry Vol. 2020; no. 17; pp. 2537 - 2541
• Main Authors: Guethner, Thomas, Huber, Evi, Sans, Juergen, Thalhammer, Franz
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 10.05.2020
• Subjects: Aqueous solutions; Cyanamide; Cyanodiazohydroxides; Diazo compounds; Nitrous oxide; Quantum mechanics; Thermal decomposition; Thermochemistry
• DOI: 10.1002/ejoc.202000181
• ISSN: 1434-193X

Nitrosation of cyanamide leads to unstable E/Z‐cyanodiazohydroxides that easily deprotonate to E/Z‐cyanodiazotates. Pursuing observations of E. Drechsel 145 years ago, the structure and reactivity of those products was determined, mainly in aqueous solution. Depending on the pH, three different thermal decomposition pathways give either N2O + HCN or N2 + HNCO. They were evaluated experimentally and by quantum mechanical calculations. The simple reaction between cyanamide and nitrous acid in aqueous solution leads to unstable azo intermediates that easily decompose into gaseous products. Principally known for 145 years, the elusive intermediates and complex reaction pathways were identified and characterized for the first time. Depending on pH conditions, either N2O + HCN or N2 + HNCO are formed by three different decomposition pathways.