Stability of Cyanogen

Abstract

Stability of CyanogenCyanogen is stable enough to be handled in the laboratory and to be stored and shipped in Monel or stainless steel cylinders 1 he word "stability," as applied to a chemical compound, is a broad term. It denotes a resistance to one or more of several different kinds of possible behavior, such as polymerization, decomposition, and chemical reaction under a variety of conditions, such as heat, pressure, addition of reagent, or mechanical shock. To be meaningful, the word must be limited in extension by a statement of the conditions under which it is true.When study of cyanogen was begun at these laboratories, there was concern about its stability. The compound is known to be chemically reactive, one of the most reactive nitriles (3, 6, 9, 7 7, 20, 22). Cyanogen has a large positive (endothermic) heat of formation, a property generally viewed as an indication of instability. The value for cyanogen is 73,-800 cal. per mole (73), as compared with 53,500 cal. per mole for acetylene (S). A third reason was the report by Berthelot that local decomposition to the elements occurred when cyanogen or acetylene vapor was heated, or was brought in contact with flame or electric spark. When mercury fulminate was used, cyanogen (and also acetvlene) detonated (2).Barillet reported that little is known of conditions for the detonation of cyanogen to the elements (7).Further evidence of the instability of cyanogen was found by Pannetier and Laffitte, in a study of the flammability limits of cyanogen air mixtures (77). When nonflammable mixtures were sparked, very brilliant luminous particles were observed in the combustion tube. The authors suggested that the particles were carbon from decomposition of cyanogen to the elements. When

The Synthesis And Chemistry Of Cyanogen

“…Cyanogen contains a high latent energy, of the same order as that of acetylene (208), which can be released explosively when the compound reacts with oxidizing agents such as fluorine (120), chlorine monoxide (5), and ozone (178), or when a mixture of cyanogen and air is subjected to a spark (42). Although an explosion hazard exists with cyanogen, the pure material has been stored and shipped in stainless-steel cylinders with no reported mishaps (208). It has also been used safely in numerous reactions other than oxidations.…”

“…A comprehensive study was recently made by Welcher, Berets, and Sentz (208) on the stability of pure cyanogen to heat, pressure, chemical additives, and severe mechanical shock. They found that pure cyanogen was unchanged after 18 to 23 days at 65°C.…”

“…It should not be concluded from these data that all the variables in the stability of cyanogen have been investigated. Until more complete data are available, it has been suggested that the literature on acetylene would be a good guide to the safe handling of cyanogen (208).…”

A New Reaction to Prepare Cyanogen

“…The heat of formation of cyanogen is extremely high (Pauling et al, 1939), but cyanogen is unexpectedly stable (Welcher et al, 1957), also, against air or oxygen. No explosion or detonation was experienced during the experiment, even when it was mixed with nitrogen dioxide.…”

“…When aqueous potassium or sodium cyanide solution is poured onto cupric sulfate powder, cyanogen is evolved (Brauer, 1963; Welcher et al, 1957;Hahn and Leopold, 1935). This reaction can be written as follows:…”