[TheodorCurtius]

Came across this interesting amateur writeup for the synthesis of many interesting compounds, including:

Hydrazine sulfate, Sodium cyanate, semicarbazide, carbamoylazide, ammonium azide, calcium cyanamide, aminoguanidine, gyanylazide, 5-aminotetrazole and sodium azide.

The report also contains a detailed OTC synthesis of potassium nitrite by reduction of potassium nitrate with copper powder. Since the public sale of nitrite has been banned in many countries, this might be useful for the amateur chemist.

The report can be found on figshare:
https://figshare.com/articles/preprint/The_amateur_synthesis_and_properties_of_some_selected_azides/24881976