Fulminic acid, mercury -salt

Fulminic Acid or Paracyanic Acid (Oxime of Carbon Monoxide) (Knallsaure in Ger Acide fulminique in Fr Gremuchaya Kislota in Russ), HONCC mw 43.03, N 32.56%, OB to C02 —55.8%. Known in solution, forms variously expl metallic salts known as fulminates. The mercury salt, apparently the first discovered was formed by the action of mercuric nitrate on ethyl alcohol (Ref 2). The free acid can be isolated in cold ether and below —5° may exist as a gas for a short time. When heated it polymerizes to meta-fulminuric acid, HC.C(=NOH)C(=NOH)O.N. Other methods of... 

Ethanamine, l,l-diaethyl-2-phenyl-Fulminic acid, mercury(II) salt (R T) Heptachlor... 

The first product of the oxidation of alcohol is acetaldehyde and an important end-product is fulminic add, which latter can, however, only be isolated if silver or mercury ions are present. With these ions it forms salts—fulminates—which are stable towards nitric add in them, it must be presumed, the linkage with the metal is homopolar and non-ionogenic, as in mercuric cyanide. The formation of fulminic acid takes place because the carbonyl group of the aldehyde confers reactivity on the adjacent methyl group which then forms a point of attack for the nitrous acid. The various stages in the process are indicated by the following formulae ... 

When mercury fulminate is boiled with water, polymerization occurs with the formation of salts of fulminic acid, which is probably a mixture of substances (VII) and (VIII). This compound hydrolyses to produce formic acid and hydroxylamine ... 

Among other fulminates, the silver salt, (CNO)2Ag, is of some importance. It is prepared in a way similar to mercury fulminate, by the action of alcohol on a silver solution in nitric acid. Silver fulminate, however, is of little value as an explosive since silver is an expensive raw material. Detonators of silver fulminate were employed only in the Italian Navy. 

Summary Silver fulminate is prepared in a similar fashion as the mercury salt by the addition of a hot nitrate acid solution upon ethyl alcohol. In this case, silver nitrate is dissolved in nitric acid, the mixture is then heated, and the ethanol dropped in. As the reaction proceeds, the silver fulminate will precipitate. It is then easily filtered-off, washed, and dried. Note Various modifications to this procedure exist. 

Fuhninic acid, C=N H C=N-OH, is a divalent carbon derivative hke carbon monoxide it is formally an oxime of carbon monoxide. Free fuhninic acid is unstable, but the explosive mercury salt, which is used as a detonator, is obtained by treatment of elemental mercury with a mixture of ethanol and lutric acid. The fulminate ion, C=N-0, like carbon monoxide and cyanide ion, functions as a strong-field... 

CNO The isomeric fulminate ion, CNO (Figure 3-5), can be drawn with three similar structures, but the resulting formal charges are unlikely. Because the order of electronegativities is C < N < O, none of these are plausible structures and the ion is predicted to be unstable. The only common fulminate salts are of mercury and silver both are explosive. Fulminic acid is linear HCNO in the vapor phase, consistent with structure C, and coordination complexes of CNO with many transition metal ions are known with MCNO structures. ... 

Fulminic Acid.—Detonating taps used for exploding the charges of gun cartridges, shells and dynamite cartridges are made of mercury fulminate, a salt of fulminic acid. This acid has the same composition as cyanic acid and iso-cyanic acid. The constitution is, however, different from either and is that of a normal iso-cyanic acid in which the hydrogen is linked as hydroxyly to the nitrogen and not directly as in iso-cyanic acid. 

Mercuric Fulminate.—The mercury and silver salts of fulminic acid are both detonating explosives the former being the one used in detonating caps. 

Tri-nitro toluene cannot be exploded by a flame nor by heating in the open, and is only slightly decomposed by striking it a blow. It is best exploded by means of a detonator of fulminate of mercury. It is used for military purposes in shells, bombs and submarine mines. It also forms a constituent of many mixed explosives. It is about 5 per cent less powerful and also less violent and less sensitive than picric acid (p. 630), and does not form sensitive salts or other products under storage conditions as does the latter. A few examples may be given of mixed explosives made with tri-nitro toluene in which ammonium nitrate is used as an oxidizer. The presence of the nitrate weakens the power of the T.N.T , but the mixtures are not very sensitive and are adapted to military purposes and some of them to mine blasting. 

Dansi (23) criticized the scheme of Wieland (Vol. Ill, p. 135). He could not obtain fulminates of mercury and silver by acting with their nitrates on iso-nitrosoacetic acid. The salts of isonitrosoacetic acid did not yield fulminates wlicn acting with nitric acid (equations 5 -8, Vol, 111, p. 135). This casts some doubt on the accuracy of Wieland s scheme. 

Mercury fulminaic tnanut aciure Storage and further processing of mercury fulminate Treatment of waste Other salts of fulminic acid Literature... 

NITRIC ACID, MERCURY(II) SALT (10045-94-0) A powerful oxidizer. Violent reaction with reducing agents, combustibles, phosphinic acid, hypophosphoric acid, petroleum hydrocarbons. Forms heat- and/or shock-sensitive compounds with acetylene (forms mercury acetylide), ethanol (forms mercury fulminate), ferrocene, isobutene, phosphine, potassium cyanide, sulfur. Incompatible with strong acids, acetic anhydride, ammonia, ammonium hexacyanoferrate(II), organic azides, citric acid, hydrazinium perchlorate. 

Fulminic Acid, C=N--OH.—Salts of this acid are obtained when nitric acid, alcohol, and mercury or silver are brought together in certain proportions. Mercuric fulminate, (CNO)2Hg, is prepared for use in percussion caps, which are used to explode gunpowder, dynamite, and other explosives. Free fulminic acid is a very unstable volatile liquid. It resembles closely hydrocyanic acid in odor and poisonous properties. 

He showed that sodium salts of aliphatic primary and secondary nitrocompounds react with acids to form carbonyl compounds 2R2CHNO2 = 2R2C0+N2O+ H2O. Nef supported the theory of bivalent carbon. In the preparation of the explosive mercuric salt of nitromethane, he found that mercury fulminate is formed and regarded fulminic acid as C N OH, the reaction being Hg(CH2 N0 0)2==Hg(0-N C)2 + 2H20. He prepared the explosive addition compound of fulminic acid and hydrogen chloride, HON CHCl. In researches on acetylene compounds he prepared explosive di-iodoacetylene, IC-CI (he formulated it IgC.-C). He discovered the reaction between sodium acetylene and a ketone, followed by hydrolysis, to form an acetylenic carbinol ... 

The other potential isomer of HOCN (in addition to isocyanic acid [H-N=C=0] and cyanic acid [H-O-CfeN]) is fulminic acid (H-0-N sC ), which is also incapable of isolation as the free acid (since attempts to do so result in polymerization). However, salts of fulminic acid are known and mercury fulminate, prepared by treatment of a mixture of mercury and ethanol with nitric add, is used commercially as a detonator (blasting cap) for explosives. 

The structure of metallic salts of fulminic acid is usually presented by a Pauling-like structure with metal bonded to carbon [3, 20-22], This seems to be a reasonable assumption even though some authors published studies supporting bonding between metal and oxygen [23] or even the possibility of the existence of both of these forms [24], The issue still causes discussion and a report of a theoretical study [22] and X-ray analysis [21], supporting the bonding between metal and carbon, was recently published. The character of the metal to carbon bond of alkaline and thalhum fulminate is ionic, whereas fulminates of silver and mercury are covalent [20, 25],... 

An alternative method of laboratory preparation of mercury fulminate is based on decomposition of the mercury salt of nitromethane published by Nef [14]. The mercuric salt is prepared in the first step of a reaction when mercuric chloride reacts with the sodium salt of nitromethane. The mercuric salt of nitromethane decomposes in a second step by boiling with dilute hydrochloric acid to produce MF [14] ... 

Unfortunately, the yield of MF is too low (only about 5 %) because the majority of the mercuric salt of nitromethane is converted into a basic mercury salt of formhydroxamic acid (also an explosive). This mercury salt cannot be converted into MF [2]. The nitromethane itself can also be converted into fulminic acid by nitrosation with nitrous acid to form nitroformaldehyde oxime. It further decomposes (by heating in water or nitric acid) to fulminic acid which is trapped with mercury nitrate as mercury fulminate [2]. 

Metallic fulminates (except mercury and silver) have never been practically used as explosives due to the difficulties with their preparation and generally low physical and chemical stability. However, the sodium salt can be used for many applications in organic chemistry. This salt is more suitable for this applicaticm than the more easily accessible mercury or silver salts due to their tendency to form complexes in solutions. For example, the sodium salt is useable in the preparation of free fulminic acid by acidification of its solution with dilute sulfuric acid [2]. 

Mercury (Quicksilver, Hydrargyrum), Hg, at wt 200.61, silvery liq, mp —38.87°, bp 356.9°, d 13.546g/cc at 20°. Insol in w, HC1, ale and eth sol In nitric acid. Sometimes found native poisonous. Can be prepd by heating the ore cinnabar (HgS) either in air or with lime. Forms numerous salts, some of which are very expl, eg, Hg fulminate, Hg azide, etc. The presence of Hg in expls, even in minute quants, is unde-sireable because it affects the result of thermal stability tests. Marshall (Ref 1) describes various tests used in Engl and Ger for its detection in different expls and propints Refs 1) Marshall 2, 708-12(1917) 2) Mellor... 

Mercury fulminate, readily formed by interaction of mercury(II) nitrate, nitric acid and ethanol, is endothermic (AH°f (s) +267.7 kJ/mol, 0.94 kJ/g) and was a very widely used detonator. It may be initiated when dry by flame, heat, impact, friction or intense radiation. Contact with sulfuric acid causes explosion [1], The effects of impurities on the preparation and decomposition of the salt have been described [2],... 

Nef [7] showed that the mercuric salt of nitromethane (obtained by the action of HgCl2 on the sodium salt of nitromethane) decomposes when boiled with dilute hydrochloric acid to produce mercury fulminate. In all probability the following reaction takes place ... 

Mercury fulminate dissolves in an aqueous solution of potassium cyanide (Steiner [25], Grigorovich [26]), to form a complex salt. According to Solonina the fulminate is best precipitated from this solution by treatment with dilute nitric acid. Thus, 12 g of mercury fulminate, dissolved in a solution of 6 g of KCN and 30 ml of water is diluted with water to 100 ml and treated carefully with 50 ml of nitric acid, i.e. 10 ml of acid, s.g. 1.40 diluted with water to 50 ml. 

Aqueous solutions of organic acids such as formic, acetic, and oxalic, decompose mercury fulminate, forming the corresponding mercuric salts. On the other hand, the action of dilute inorganic acids involves decomposition with formation of C02. 

---