High purity nitrous oxide can be synthesized via the reaction of ammonium nitrate (NH4NO3) with nitric acid (HNO3) (the latter can be generated from H2SO4 and urea). The resulting gas will be a mixture of N2O and CO2. The latter is removed alongside any adventitious O2 by bubbling the gas through a 10% aqueous solution of NaOH and a small amount of pyrogallol. The scrubbed gas is then passed through a column loaded with drying agent (i.e. CaCl2) to yield pure N2O.
The reaction is believed to proceed via initial formation of urea nitrate (nitric acid + urea). Urea nitrate can then be dehydrated by H2SO4 to form nitrourea, which then hydrolyzes to carbamic acid and the simplest nitramide (NH2NO2). Carbamic acids are labile and ultimately break down into an amine (NH3) and CO2, while NH2NO2 breaks into nitrous oxide and water.
For more details on experimental setup, mechanism, and procedure, please refer to pages S9-S13 from the Supporting Information in the reference below.
Puerta Lombardi, B. M.; Gendy, C.; Gelfand, B.; Bernard, G. M.; Wasylishen, R. E.; Tuononen, H. M.; Roesler, R. Side-on Coordination in Isostructural Nitrous Oxide and Carbon Dioxide Complexes of Nickel. Angew. Chem. Int. Ed. 2021, 60, 13, 7077-7081.