The preparation of tetramethylguanidium azide was successfully carried out following the literature preparation (JOC 31, 1426 (1966)). Hydrazoic acid was prepared as a Et2O solution by adding conc HCl over 30 minutes to a ice cold solution of NaN3 in water followed by an Et2O extraction. The literature did not provide the volume of Et2O employed, so the extraction was done using a volume equivalent to the amount of water that was present. The literature also states that a dry Et2O solution of HN3 was used. This is ambiguous as no drying operation was mentioned, so the HN3 solution was dried over MgSO4 followed by filtration. This solution was added to an ether solution of tetramethylguanidine at 0 over 3 hours. There was no mention of the reaction appearance, but the suspension was allowed to warm to rt and stirred overnight. The white crystalline solid was isolated by filtration using a cold Et2O rinse. The product was clean enough for use and was not recrystallized. It was stored in a drybox due to its hydroscopicity.