Tetrazene manufacture

Tetrazene is a light yellow crystalline substance, insoluble in water and most organic solvents. The density is low under normal conditions, but on pressing can reach approximately 1 g ml-1. Tetrazene is weak as an initiating explosive, and is therefore not used alone. It has no advantages to commend it for use in commercial detonators, but does find application in the manufacture of military and other percussion caps. Like diazodinitrophenol, tetrazene does not detonate when ignited in the open, but only when ignited under confinement. 

Despite the fact that LA, LS and tetrazene suffer from serious drawbacks, they are still being used in detonators and cap compositions for military and civil applications. Thus LA, LS and tetrazene are the most commonly used primary explosives at present and research is in progress in order to find out suitable substitutes free from such drawbacks. The aim of research in initiatory explosives has all along been to get less sensitive, more compatible, more stable and more efficient material so that safety in manufacture and handing is ensured. 

On reduction, nitroguanidine is converted first into nitrosoguanidine and then into aminoguanidine i.e. guanylhydrazine. The latter is used for the manufacture of tetrazene (p. 206), and in organic chemistry to form crystalline derivatives from aldehydes and ketones, just as semicarbazide forms semicarbazones. 

Fig. 49. Diagram of the design and operation of a reactor for the manufacture of lead azide and other primary explosives (tetrazene, lead styphnate and lead picrate).

Tetrazene is a relatively weak primary explosive. It should always be used with a sensitive booster charge such as PtTN. When used in the manufacture of detonators, tetrazene should be freely poured into a capsule. Tetrazene loses much of its effectiveness when pressed. 

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