Hydrogen cyanide, structure

Legon A 0, Millen D J and Mjdberg P J 1977 The hydrogen cyanide dimer identification and structure from microwave spectroscopy Chem. Phys. Lett. 47 589... 

Dulmage W J and Lipscomb W N 1951 The crystal structures of hydrogen cyanide, HON Acta Crystallogr. 4 330... 

Lewis s concept of shared electron parr bonds allows for four electron double bonds and SIX electron triple bonds Carbon dioxide (CO2) has two carbon-oxygen double bonds and the octet rule is satisfied for both carbon and oxygen Similarly the most stable Lewis structure for hydrogen cyanide (HCN) has a carbon-nitrogen triple bond... 

The use of fire retardants in polymers has become more complicated with the realisation that more deaths are probably caused by smoke and toxic combustion products than by fire itself. The suppression of a fire by the use of fire retardants may well result in smouldering and the production of smoke, rather than complete combustion with little smoke evolution. Furthermore, whilst complete combustion of organic materials leads to the formation of simple molecules such as CO2, H2O, N2, SO2 and hydrogen halides, incomplete combustion leads to the production of more complex and noxious materials as well as the simple structured but highly poisonous hydrogen cyanide and carbon monoxide. 

Mechanistically it is an electrophilic aromatic substitution reaction. The electrophilic species (4—its exact structure is not known) is generated in a reaction of hydrogen cyanide and hydrogen chloride (gas) and a Lewis acid ... 

Alternatively a Mannich-like pathway may be followed (see Mannich reaction), where ammonia reacts with the aldehyde 1 to give an intermediate iminium species, that adds hydrogen cyanide to give the a-amino nitrile 2. The actual mechanistic pathway followed depends on substrate structure and reaction conditions. 

Naturally occurring compounds called cyanogenic glycosides, such as lotau-stralin, release hydrogen cyanide, HCN, when treated with aqueous acid. The reaction occurs by hydrolysis of the acetal linkage to form a cyanohydrin, which then expels HCN and gives a carbonyl compound-fa) Show the mechanism of the acetal hydrolysis and the structure of the cyanohydrin that results. 

Schrobilgen, G, J., J. Chem. Soc., Chem. Comm., 1988, 863 A white solid precipitating from hydrogen cyanide and fluorokrypton in hydrogen fluoride is attributed this structure. It decomposes rapidly above — 50°C, usually with violent detonation. 

Both types of hydrogen bonds occur in pure liquids as well as in solutions. Many substances are associated at least partially in the vapor phase as a result of hydrogen bonding. For example, hydrogen cyanide is associated to give structures such as... 

Finally, when L-sorbose (81) was treated with hydrogen cyanide, a branched-chain, sugar lactone was formed which was characterized by converting it into a diacetal.127 An X-ray structure determination of this material revealed it to be 2,21 5,6-di-0-isopropylidene-[2-C-(hy-droxymethyl)-L-gulono-l,4-lactone] (82). However, all subsequent efforts to prepare 82 resulted in the formation of 2,3 5,6-di-0-isopropyli-dene-2-C-(hydroxymethyl)-L-gulono-l,4-lactone (83). 

In Chapter 1 we have stated that the classical structural theory is the only way to "visualise" the synthesis of a more or less complex organic compound. However, all or most of the information given by a structural formula can also be expressed.by a matrix (see also Appendix A-1). There are different kinds of matrices for example, the adjacency matrix J, which originates in graph theory and indicates only which atoms are bonded, or the connectivity matrix C, whose off-diagonal entries are the formal covalent bond orders. For instance, the corresponding matrices of hydrogen cyanide are ... 

The BE-matrices of hydrogen cyanide and hydrogen isocyanide (notice that since the neutral "carbenic" resonance structure has not the octets fully completed, the dipolar resonance structure is taken instead) are ... 

The apparently quite broad structural requirements for anticonvulsant activity, noted earlier in this chapter, extend to yet another class of five-membered heterocycles that include an imide function. Imidazo-2,4-diones, better known as hydan-toins, have comprised some of the most widely used drugs for treating severe motor and psychomotor epileptic seizures. The general reaction used to prepare this heterocyclic system involves the treatment of a carbonyl compound with ammonium carbonate and potassium cyanide. The first step in the complex sequence can be visualized as the addition of the elements of ammonia and hydrogen cyanide to give an a-aminonitrile (88-2). Addition of ammonia to the cyano group would then lead to an amidine (88-3). Carbon dioxide or carbonate ion present in the reaction... 

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