Mercury(II) fulminate

Mercury(II) fulminate is prepared by dissolving mercury in nitric acid and adding ethanol to the solution. Edward Charles Howard is credited with first preparing it in 1800. However, Johann Kunckel had discovered the compound more than a century before in the 17th century. The crystal structure of this compound was determined only in 2007. Silver fulminate can be prepared in a similar way, but this salt is even more unstable than mercury fulminate; it can explode even under water and is impossible to accumulate in large amounts because it detonates under its own weight. Another preparation method is through reaction of the sodium salt of nitromethane with an aqueous solution of mercury(II) chloride () at to form a white precipitate of mercuric nitromethanate. This is digested with warm, dilute hydrochloric acid (HCl) to produce mercury(II) fulminate. Intermediates The oxidation and nitration of ethanol with nitric acid proceeds through a multitude of intermediate compounds before reaching mercury fulminate; acetaldehyde (), nitrosoacetaldehyde (, isonitrosoacetaldehyde (), isonitrosoacetic acid (), nitroisonitrosoacetic acid (), formonitrolic acid (), and fulminic acid () are first formed. The last reacts with mercury to produce the fulminate. ==Decomposition==

The thermal decomposition of mercury(II) fulminate can begin at temperatures as low as , though it proceeds at a much higher rate with increasing temperature. It may be decomposed with relative safety by reaction with ten times its weight of 20% sodium thiosulfate solution. This may evolve some toxic cyanogen gas. A possible reaction for the decomposition of mercury(II) fulminate yields carbon dioxide gas, nitrogen gas, and a combination of relatively stable mercury salts. : : : : ==See also==