Preparation of 1-(2-hydroxyethyl)tetrazole
60 ml of acetic acid were added with stirring to a mixture of 12.2 g (0.2 moles) of monoethanolamine, 14.3 g (0.22 moles) of sodium azide, and 60 ml of ethyl orthoformate and the mixture was heated at 80-90° C for 3 h. It was then cooled and treated with 22 ml of concentrated hydrochloric acid, and the mixture was filtered. The filtrate was evaporated in vacuo to give 21.3 g of crude 1-(2-hydroxyethyl)tetrazole, which was dissolved in 50 ml of ethanol. The ethanol solution was heated to the boiling point, and a solution of 17.1 g (0.1 moles) of copper(II) chloride (CuCl2 · 2H2O) in 50 ml of boiling ethanol was added to it. The solution was cooled to 0-5° C and the 1-(2-hydroxyethyl)tetrazole complex with Cu2+ that crystallized out was separated, washed with cold ethanol, and dried to give 29.8 g (83%) of copper complex of 1-(2-hydroxyethyl)tetrazole with melting point of 163-165°C (with decomp.). The crystals were then dissolved in 50 ml of water, and hydrogen sulfide was passed into the solution until the copper precipitated completely by forming copper(II) sulfide. The solution was filtered, the filtrate was evaporated in vacuo, and the residue was extracted with tetrahydrofuran. The extract was dried with molecular sieves, and the solvent was removed by distillation yielding 18.0 g (79%) of a product with melting point 36-38° C that was soluble in water, alcohols, and tetrahydrofuran but insoluble in ethyl acetate, chloroform, and ether.
Chemistry of Heterocyclic Compounds, 1985, 21 (10), 1172-1174