Cyanides adiponitrile

Hydrogen cyanide in pure form was prepared first in 1815 by Gay-Lussac. Earher, in 1782, Scheel prepared this compound in dilute solution. The most important apphcation of hydrogen cyanide is to produce methyl methacrylate for methacrylate resins and plastics. Other products made from hydrogen cyanide include potassium cyanide, sodium cyanide, adiponitrile, methionine, cyanuric chloride, cyanogen, nitrilotriacetic acid, and several triazine pesticides. The compound also is used in small amounts for extermination of rodents. 

In the now-obsolete furfural process, furfural was decarboxylated to furan which was then hydrogenated to tetrahydrofuran (THF). Reaction of THF with hydrogen chloride produced dichlorobutene. Adiponitrile was produced by the reaction of sodium cyanide with the dichlorobutene. The overall yield from furfural to adiponitrile was around 75%. 

In a related process, 1,4-dichlorobutene was produced by direct vapor-phase chlorination of butadiene at 160—250°C. The 1,4-dichlorobutenes reacted with aqueous sodium cyanide in the presence of copper catalysts to produce the isomeric 1,4-dicyanobutenes yields were as high as 95% (58). The by-product NaCl could be recovered for reconversion to Na and CI2 via electrolysis. Adiponitrile was produced by the hydrogenation of the dicyanobutenes over a palladium catalyst in either the vapor phase or the Hquid phase (59,60). The yield in either case was 95% or better. This process is no longer practiced by DuPont in favor of the more economically attractive process described below. 

Estimates of various uses for hydrogen cyanide in the United States ate adiponitrile for nylon, 41% acetone cyanohydrin for acryhc plastics, 28% sodium... 

In a typical process adiponitrile is formed by the interaction of adipic acid and gaseous ammonia in the presence of a boron phosphate catalyst at 305-350°C. The adiponitrile is purified and then subjected to continuous hydrogenation at 130°C and 4000 Ibf/in (28 MPa) pressure in the presence of excess ammonia and a cobalt catalyst. By-products such as hexamethyleneimine are formed but the quantity produced is minimized by the use of excess ammonia. Pure hexamethylenediamine (boiling point 90-92°C at 14mmHg pressure, melting point 39°C) is obtained by distillation, Hexamethylenediamine is also prepared commercially from butadience. The butadiene feedstock is of relatively low cost but it does use substantial quantities of hydrogen cyanide. The process developed by Du Pont may be given schematically as ... 

Hydrogen cyanide (prussic acid) is a liquid with a boiling point of 26°C. Its vapour is flammable and extremely toxic. The effects of acute exposure are given in Table 5.34. This material is a basic building block for the manufacture of a range of chemical products such as sodium, iron or potassium cyanide, methyl methacrylate, adiponitrile, triazines, chelates. 

Adiponitrile (Tetramethylene cyanide) CN(CH,)4CN Can behave as a cyanide when ingested or otherwise absorbed into the body Combustion products may contain HCN Water-white, practically odourless liquid Elash point 93°C Specific gravity 0.97 Vapour density 3.7... 

The major use of hydrogen cyanide in the United States today is for the production of adiponitrile, wliich is used primarily as an inlcrnicdiate for liexamelliylenediamine. Tliis intermediate is the primary ingredient for tlie production of nylon 6,6." Anotlier major use of hydrogen cyanide is for tlie... 

Hydrogen cyanide (hydrocyanic acid) is a colorless liquid (b.p. 25.6°C) that is miscible with water, producing a weakly acidic solution. It is a highly toxic compound, but a very useful chemical intermediate with high reactivity. It is used in the synthesis of acrylonitrile and adiponitrile, which are important monomers for plastic and synthetic fiber production. 

Hydrogen cyanide is a reactant in the production of acrylonitrile, methyl methacrylates (from acetone), adiponitrile, and sodium cyanide. It is also used to make oxamide, a long-lived fertilizer that releases nitrogen steadily over the vegetation period. Oxamide is produced by the reaction of hydrogen cyanide with water and oxygen using a copper nitrate catalyst at about 70°C and atmospheric pressure ... 

Hexamethylenediamine is discussed in Chapter 10, Sections 1 and 8. It is produced from adiponitrile by hydrogenation. Adiponitrile comes from electrodimerization of acrylonitrile (32%) or from anti-Markovnikov addition of 2 moles of hydrogen cyanide to butadiene (68%). 

Adiponitrile production accounts for 41% of hydrogen cyanide use, methyl methacrylate for 32%. Other uses include sodium cyanide (14%, a... 

Hydrogen cyanide is an important building block chemical for the synthesis of a variety of industrially important chemicals, such as 2 hydroxy-4 methylthiobutyric acid, adiponitrile, nitrilotriacetic acid, lactic acid, and methyl methacrylate. The primary commercial routes to hydrogen cyanide are the reaction of methane and ammonia under aerobic (Andrussow Process) or anaerobic conditions (Degussa Process), or the separation of hydrogen cyanide as a by-product of the ammoxidation of propylene < ) The ammoxidation of methanol could represent an attractive alternate route to HCN for a number of reasons. First, on a molar basis, the price of methanol has become close to that of methane as world methanol capacity has increased. However, an accurate long term pricing picture for these two raw... 

Hydrogen cyanide can be added across olefins in the presence of Ni, Co, or Pd complexes (Scheme 56) (123). Conversion of butadiene to adiponitrile is a commercial process at DuPont Co. The reaction appears to occur via oxidative addition of hydrogen cyanide to a low-valence metal, olefin insertion to the metal-hydrogen bond, and reductive elimination of the nitrile product. The overall reaction proceeds with cis... 

In recent years hydrogen cyanide (HCN) has been replaced by ammonia as u raw material for producing acrylonitrile. A large portion of hydrogen cyanide is used in (he manufacture of methyl methacrylate, adiponitrile, and sodium cyanide. The preferred method of manufacturing hydrogen cyanide is to react methane, ammonia, and air over a platinum catalyst at a temperature above lOOri C... 

Hexanedinitrile (adiponitrile). Use 150 ml of dry dimethyl sulphoxide, 21.2 g (0.17mol) of 1,4-dichlorobutane (Expt 5.52) and 20g (0.41 mol) of dried sodium cyanide. Maintain the reaction temperature at 90 °C for a further 15 minutes after the initial exothermic reaction has subsided. Add 150 ml of dichloromethane to the cooled reaction mixture and pour into an excess of saturated sodium chloride solution in a separatory funnel. Add just sufficient water to dissolve precipitated salts and separate the dichloromethane layer. Extract the acqueous layer once with dichloromethane, wash the combined extracts twice with salt solution, dry over magnesium sulphate and remove the solvent using a rotary evaporator. Fractionally distil the residue under reduced pressure and collect the adiponitrile as a fraction of b.p. 140-141 °C/ 1.5mmHg. The yield is 14.6g (81%). Some dimethyl sulphoxide (b.p. 40-42°C/1.5mmHg) may be obtained as a forerun. 

Hydrogen cyanide is used for the production of methyl methacrylate, adiponitrile, cyanuric chloride, and chelating agents. 

Manufacture of acrylonitrile, acrylates, adiponitrile, cyanide salts, dyes, chelates, rodenticides, and pesticides. 

The U.S. demand in 2000 was about 1.6 billion lb. Uses for hydrogen cyanide include adiponitrile (for nylon 6/6), 47 percent methyl methacrylate, 27 percent sodium cyanide, 8 percent methionine, 6 percent and chelating agents, 2 percent. 

In 2004 HCN was consumed in the following applications adiponitrile (for nylon 6/6) 50 percent, acetone cyanohydrin (for methyl methacrylate) 28 percent, methionine 7 percent, sodium cyanide 6 percent, cyanuric chloride 3 percent, chelating agents 2 percent, and miscellaneous (including nitrilotri-acetic acid and salts) 4 percent.261... 

The initial drive for acrylonitrile (AN) production (6.2 Mt/a in 2004 worldwide) was the discovery, in the late 1930s, of the synthetic rubber Buna N. Today nitrile rubbers represent only a minor outlet for AN which is utilized primarily for polymerization to give textile fibres (50%) and ABS resins (24%), and for dimerization to adiponitrile (10%). Early industrial processes depended on the addition of hydrogen cyanide to acetylene or to ethylene oxide, followed by the dehydration of intermediate ethylene cyanohydrin. Both processes are obsolete and are now supplanted by the ammoxidation of propylene (Equation 34) introduced in 1960 by Standard Oil of Indiana (Sohio). The reason for the success stems from the effectiveness of the catalyst and because propylene,... 

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