Adiponitrile, other routes

Adiponitrile is an important intermediate for producing nylon 66. There are other routes for its production, which are discussed in Chapter 9. The way to produce adiponitrile via propylene is the electrodimerization of acrylonitrile. The following is a representation of the electrochemistry involved ... 

Though how optimized and elaborate the process has become, it competes with other routes. For adiponitrile, the nickel-catalyzed hydrocyanation of butadiene is today regarded as the most cost-effective route [28]. This route has originally been developed at DuPont [27] and it is sensitive to the natural gas price, while for the electrohydrodimerization, the propylene price is of interest. Today adiponitrile is produced for the most part by hydrocyanation [28]. This makes an industrial aspect of organic electrochemistry very clear the electrolysis has to generate a profitable product. The efficiency of a process with high yields is one step to this profitable product. In the end factors like the raw material basis may make the difference between being competitive and not especially for a commodity like adiponitrile. 

Controlled current reduction of a mixture of two activated alkenes will yield a mixture of the two possible hydrodimers together with the hydrocoupled product, provided that the reduction potentials of the two substrates are not too far apart [133], This can be a useful synthetic route to the hydrocoupled product provided that the other products are themselves valuable. Thus, reduction of a mixture of 1-cyanobutadiene with excess acrylonitrile, followed by catalytic hydrogenation of the products, gives a synthesis of 1,6-dicyanohexane with adiponitrile as the side product [133]. 

The manufacture of hexamethylenediamine [124-09-1], a key comonomer in nylon-6,6 production proceeds by a two-step HCN addition reaction to produce adiponitrile [111 -69-3], NCCH2CH2CH2CH2CN. The adiponitrile is then hydrogenated to produce the desired diamine. The other half of nylon-6,6, adipic acid (qv), can also be produced from butadiene by means of either of two similar routes involving the addition of CO. Reaction between the diamine and adipic acid [124-04-5] produces nylon-6,6. 

Currently, adiponitrile is the only organic chemical produced in large quantity (108 kg/yr) by an electrochemical route. Other smaller-scale products include gluconic acid, piperidine, and p-aminophenol. Electroorganic syntheses in supercritical organic electrolytes have been demonstrated in bench-scale reactors. Production of dimethyl carbonate from the mixture-critical region was performed. There are at least a dozen electroorganic processes that are... 

The acute toxicity of adiponitrile is somewhat lower than that of malononitrile. It is toxic by inhalation and oral routes. Inhalation of its vapors can cause nausea, vomiting, respiratory tract irritation, and dizziness. The symptoms are similar to those of other aliphatic mono- and dinitriles. Similar poisoning effects may be manifested from ingestion of this compound. However, its toxicity is very low from skin absorption. 

The ammoxidation process ( eq. 8 ) displaced the more expensive acetylene-HCN-based route in the early 1960 s (eq. 20). Other obsolete processes also involve more expensive reagents (e.g. ethylene oxide, eq. 19, and acetaldehyde, eq. 21) and oxidants (e.g. NO, eq. 22). The impact of the introduction of the ammoxidation process in 1960 was an immediate drastic reduction in acrylonitrile price and greatly increased production which made possible many of today s high-volume applications of acrylonitrile (Figure 6A). The production of acrylonitrile, which accounts for 17% of the total U. S. propylene consumption, is used extensively in fibers, plastics and resins (ARS/SA) and rubber industries, with a growing number of miscellaneous applications, including the electro-hydrodimerization process for adiponitrile production (Figure 6B). 

Other chemical routes to adiponitrile are available, namely OH... 

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