Hydrocyanic acid manufacture

Uses Fumigant and larvacide for tobacco, cereals, dried fruits cellulose acetate solvent military poison gases intermediate in manufacture of pharmaceuticals, hydrocyanic acid, N,N-dimethylformamide organic synthesis. 

FORMAMIDE. Form amide (meibanamide), HCONHi. is the lirsi member of the primary amide series and is the only one liquid at room temperature. II is hygroscopic and has a faint odor of ammonia. Formamide is a colorless to pale yellowish liquid, freely miscible with water, lower alcohols and glycols, and lower esters and acetone. It is virtually immiscible in almost all aliphatic and aromatic hydrocarbons, chlorinated hydrocarbons, and ethers. By virtue of its high dielectric constant, close to that of water and unusual for an organic compound, formamide has a high solvent capacity lor many heavy-metal salts and for salts of alkali and alkalinc-carth metals. It is an important solvent, in particular for resins and plasticizers. As a chemical intermediate, formamide is especially useful in the synthesis of heterocyclic compounds, pharmaceuticals, crop protection agents, pesticides, and for the manufacture of hydrocyanic acid. 

Until a few years ago, hydrocyanic acid was always prepared by heating potassium ferrocyanide with dilute sulphuric acid. Nowadays, it is preferred to employ the alkali cyanides, either sodium or potassium, as these are manufactured synthetically on a large scale and very cheaply. Usually 50% aqueous sulphuric acid is run on to sodium cyanide either in concentrated solution or in lumps, and then the mixture heated in order to drive off the hydrocyanic acid. As it is evolved, the acid is dried by passing through calcium chloride and then liquefied by passing it first... 

Formamide is a good solvent for proteins and salts owing to its high dielectric constant. Its main applications are as a solvent in the chemical industry, as a softener for paper, as an intermediate for the manufacturing of formic acid and esters and hydrocyanic acid, and as a reaction medium. 

Benzaldehyde, benzoic aldehyde, CeHs.CHO, occurs in amygdalin, a glucoside which is present in bitter almonds and in the kernels of various fruits it yields the aldehyde, hydrocyanic acid, and glucose on hydrolysis (353). The aldehyde is called oil of bitter almonds. It is used in flavoring extracts and perfumery, in the manufacture of certain dyes, and in the preparation of other compounds. 

Hydrocyanic acid, HCN, is corrosive in addition to toxic. It is also a dangerous fire and explosion risk. It has a wide flammable range of 6 to 41% in air. The boiling point is 79 F, the flash point is 0°F, and the ignition temperature is 1004°F. It is toxic by inhalation, ingestion, and through skin absorption. The TLV of hydrocyanic acid is 10 ppm in air. It is used in the manufacture of acrylonitrile, acrylates, cyanide salts, dyes, rodenticides, and other pesticides. 

Hydrogen cyanide, HCN, is an extremely toxic gas that famously has the odor of bitter almonds. It is produced by the reaction of a cj anide salt, such as NaCN, with an acid. Aqueous solutions of HCN are known as hydrocyanic acid. Neutralization with a base produces cyanide salts, which are used in the manufacture of several plastics, including nylon and Orion . The CN ion forms stable complexes with most transition metals. (Section 17.5)... 

HYDROGEN CYANIDE GAS. HCN (SEE ALSO HYDROCYANIC ACID. In laboratory tests, alloy 3003 was resistant to hydrogen cyanide gas at am bient temperature. Aluminum alloy heat exchangers, reactor towers, tanks, and piping have been used in the manufacture of hydrogen cyanide gas. See also Ref (2)p. 368, (3) p. 51. 

Propylene and a-alkenes can be reacted with synthesis gas to give -butyraldehyde and alcohols, respectively. These reactions are called hydroformylation or oxo-reactions. The reaction between butadiene and hydrocyanic acid to obtain adiponitrile is called hydrocyanation. The mechanistic details and the relevance of hydroformylation and hydrocyanation reactions for the manufacture of consumer products are discussed in Chapter 5. 

The cyanide ion, CN , is similar to the halide ions, X , in that it forms an insoluble silver salt, AgCN, and an acid, HCN. Hydrocyanic acid, HCN, is a liquid that boils at about room temperature. It is a very weak acid, unlike HCl. Despite its extreme toxicity, HCN has important uses in the manufacture of plastics. The combination of two cyanide groups produces cyanogen, (CN)2. This gas resembles chlorine gas in undergoing a disproportionation reaction in basic solution ... 

The remarkably versatile Ci building block HCN may be used in the aqueous two-phased hydrocyanation, too (Equation 5.3 [37]). Also, some fine chemicals such as intermediates for vitamins, phenyl acetic acid, etc. are manufactured on an industrial scale using this technology (Equations 5.4 and 5.5 [12e,31b,38]). 

Among other nonaddition processes, adiponitrile may be manufactured by the direct hydrocyanation of 1,3-butadiene (DuPont process).169 172,187 196 A homogeneous Ni(0) complex catalyzes both steps of addition of HCN to the olefinic bonds (Scheme 6.4). The isomeric monocyano butenes (20 and 21) are first formed in a ratio of approximately 1 2. All subsequent steps, the isomerization of 20 to the desired 1,4-addition product (21), a further isomerization step (double-bond migration), and the addition of the second molecule of HCN, are promoted by Lewis acids (ZnCl2 or SnCl2). Without Lewis acids the last step is much slower then the addition of the first molecule of HCN. Reaction temperatures below 150°C are employed. 

The Du Pont process for the manufacture of adiponitrile (1,4-dicyanobutane) from butadiene depends on nickel catalysed hydrocyanation. Adiponitrile is the precursor to 1,6-diaminohexane which is used to make Nylon 6,6. The other component, adipic acid (1,6-hexanedioic acid) is usually made by oxidation of cyclohexane, although in principle it could also be obtained from the dinitrile. The... 

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