Synthesis of Adiponitrile

Adiponitrile is used as an important synthon for hexamethylene diamine and adipic acid, which are used for the manufacture of Nylon-66. 

It is obtained commercially by the electroreductive coupling of acrylonitrile. By this process about 90% of adiponitrile is obtained. In this process a concentrated solution of certain quaternary ammonium salts (QASs), such as 

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The aqueous layer remaining after extraction with n-butanol was acidified (to pH 1) by the addition of 50% sulfuric acid, giving a precipitate of adipic acid which was collected by filtration, washed with 120 parts of water in two equal portions, and dried at 110° C. The crude adipic acid obtained was recrystallized from twice its weight of water to provide adipic acid in 90.2% yield, which was pure enough to be used in the synthesis of adiponitrile. 

In the previously described reactions, the basicity of anion radicals and their reactions with proton donors was emphasized. In the absence of viable proton donors or even in their presence, if the anion radical is relatively stable, radical coupling may be the dominant reaction. Thus even in aqueous solution, the anion radicals of alkenes substituted with strongly electron withdrawing moieties may undergo coupling in preference to protonation. The synthesis of adiponitrile from acrylonitrile (Scheme 71) is an outstanding example [118]. 

Synthesis of adiponitrile from pentenenitrile has been reported using te-trakis(triarylphosphite)palladium(0), but no report of 1,3-butadiene hydrocyanation by... 

Hexamethylenediamine (HMDA) is a precursor for nylon 6/6. There are numerous routes to HMDA, but all of the commercial processes involve the synthesis of adiponitrile and the subsequent hydrogenation of adiponitrile to HMDA. The dominant process is the reaction of hydrogen cyanide with 1,3 butadiene to form adiponitrile followed by hydrogenation of adiponitrile to hexamethylene diamine. 

The addition of HCN to C=C double bonds can be effected in low yields to produce Markovnikov addition products. However, through the use of transition metal catalysts, the selective anti-Markovnikov addition of HCN to alkenes can take place. The most prominent example of the use of aqueous media for transition metal-catalyzed alkene hydrocyanation chemistry is the three-step synthesis of adiponitrile... 

The synthesis of adiponitrile commercialized by DuPont requires the high regioselective addition of two moles of HCN to butadiene ... 

Dai JJ, Hnang YB, Eang C, Guo QX, Eu Y. (2012). Electrochemical synthesis of adiponitrile from the renewable raw material glutamic acid. ChemSusChem, 5, 617-620. 

The addition of HCN to olefins catalyzed by complexes of transition metals has been studied since about 1950. The first hydrocyanation by a homogeneous catalyst was reported by Arthur with cobalt carbonyl as catalyst. These reactions gave the branched nitrile as the predominant product. Nickel complexes of phosphites are more active catalysts for hydrocyanation, and these catalysts give the anti-Markovnikov product with terminal alkenes. The first nickel-catalyzed hydrocyanations were disclosed by Drinkard and by Brown and Rick. The development of this nickel-catalyzed chemistry into the commercially important addition to butadiene (Equation 16.3) was conducted at DuPont. Taylor and Swift referred to hydrocyanation of butadiene, and Drinkard exploited this chemistry for the synthesis of adiponitrile. The mechanism of ftiis process was pursued in depth by Tolman. As a result of this work, butadiene hydrocyanation was commercialized in 1971. The development of hydrocyanation is one of tfie early success stories in homogeneous catalysis. Significant improvements in catalysts have been made since that time, and many reviews have now been written on this subject. ... 

Thus, the electrochemical route for synthesis of adiponitrile effectively halved the demand for adipic acid. 

The success of the hlterpress cell has been demonstrated for a diverse range of electrolytic applications, including large-scale water electrolysis and synthesis of adiponitrile. 

It is well know that nickel(O) complexes play a crucial role in the commercial synthesis of adiponitrile (AdN), the major nylon-6,6 precursor. In the global process, the isomerization of the branched 2-methyl-3-butenenitrile (2M3BN) to the linear 3-pentenenitrile (3PN) is a key step. " Such isomerization is obtained through the C-CN bond activation involving a Ni° intermediate. 

Presently the number of industrial processes using metal complex catalysts is continuously increasing. They include such classical large-tonnage processes as polymerization on the Ziegler catalysts, olefin oxidation by molecular oxygen to aldehydes, hydroformylation of saturated compounds, preparation of acetic acid from methanol and carbon monoxide, synthesis of adiponitrile fijom butadiene, and others. 

It is well known that nickel(O) complexes play a crucial role in the commercial synthesis of adiponitrile (AdN), the major nylon-6,6 precursor. In the... 

A special feature of the electrochemical synthesis of adiponitrile and other dinitrides is their behavior in aqueous solutions of the hydrotropic salts which serve as electrolytes. 

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