To acrylonitrile

Other routes to acrylonitrile, none of which achieved large-scale commercial appHcation, are acetaldehyde and HCN (56), propionittile dehydrogenation (57,58), and propylene and nitric oxide (59,60) ... 

Numerous patents have been issued disclosing catalysts and process schemes for manufacture of acrylonitrile from propane. These include the direct heterogeneously cataly2ed ammoxidation of propane to acrylonitrile using mixed metal oxide catalysts (61—64). 

A two-step process involving conventional nonoxidative dehydrogenation of propane to propylene in the presence of steam, followed by the catalytic ammoxidation to acrylonitrile of the propylene in the effluent stream without separation, is also disclosed (65). 

The propylene-based process developed by Sohio was able to displace all other commercial production technologies because of its substantial advantage in overall production costs, primarily due to lower raw material costs. Raw material costs less by-product credits account for about 60% of the total acrylonitrile production cost for a world-scale plant. The process has remained economically advantaged over other process technologies since the first commercial plant in 1960 because of the higher acrylonitrile yields resulting from the introduction of improved commercial catalysts. Reported per-pass conversions of propylene to acrylonitrile have increased from about 65% to over 80% (28,68—70). 

Acrylonitrile is beheved to behave similarly to hydrogen cyanide (enzyme inhibition of cellular metaboHsm) (150) and is befleved to be a potential carcinogen (151). It can also affect the cardiovascular system and kidney and Hver functions (150). Eurther information on the toxicology and human exposure to acrylonitrile is available (152—154) (see Acrylonitrile). 

National Institute for Occupational Safety and Health, "A Recommended Standard for Occupational Exposure to Acrylonitrile," DHEW Publ. No. 78—116, U.S. Government Printing Office Washington, D.C., 1978. 

Addition of Hydrogen Cyanide. At one time the predominant commercial route to acrylonitrile was the addition of hydrogen cyanide to acetylene. The reaction can be conducted in the Hquid (CuCl catalyst) or gas phase (basic catalyst at 400 to 600°C). This route has been completely replaced by the ammoxidation of propylene (SOHIO process) (see Acrylonitrile). 

Oxidation Catalysis. The multiple oxidation states available in molybdenum oxide species make these exceUent catalysts in oxidation reactions. The oxidation of methanol (qv) to formaldehyde (qv) is generally carried out commercially on mixed ferric molybdate—molybdenum trioxide catalysts. The oxidation of propylene (qv) to acrolein (77) and the ammoxidation of propylene to acrylonitrile (qv) (78) are each carried out over bismuth—molybdenum oxide catalyst systems. The latter (Sohio) process produces in excess of 3.6 x 10 t/yr of acrylonitrile, which finds use in the production of fibers (qv), elastomers (qv), and water-soluble polymers. 

Primary cycloaUphatic amines react with phosgene to form isocyanates. Reaction of isocyanates with primary and secondary amines forms ureas. Dehydration of ureas or dehydrosulfuri2ation of thioureas results in carhodiimides. The nucleophilicity that deterrnines rapid amine reactivity with acid chlorides and isocyanates also promotes epoxide ring opening to form hydroxyalkyl- and dihydroxyalkylaniines. Michael addition to acrylonitrile yields stable cyanoethylcycloalkylarnines. 

Catalysts. In industrial practice the composition of catalysts are usuaUy very complex. Tellurium is used in catalysts as a promoter or stmctural component (84). The catalysts are used to promote such diverse reactions as oxidation, ammoxidation, hydrogenation, dehydrogenation, halogenation, dehalogenation, and phenol condensation (85—87). Tellurium is added as a passivation promoter to nickel, iron, and vanadium catalysts. A cerium teUurium molybdate catalyst has successfliUy been used in a commercial operation for the ammoxidation of propylene to acrylonitrile (88). 

An important industrial partial oxidation process is the conversion of propylene to acrylonitrile (26) ... 

Indazole adds to acrylonitrile and 4-vinylpyridine giving 1- or 2-substituted derivatives depending on the 7-substituents (69BSF2064). It also reacts with epoxystyrene to form (259). 

Acrylonitrile. Acrylonitrile is produced by reacting propylene, ammonia, and owgeu (air) in a single flmdized bed of a complex catalyst. Known as the SOHIO process, this process was first operated commercially in 1960. In addition to acrylonitrile, significant quantities of HCN and acetonitrile are also produced. This process is also exothermic. Temperature control is achieved by raising steam inside vertical tubes immersed in the bed [Veatch, Hydrocarbon Proce.ss. Pet. Refiner, 41, 18 (November 1962)]. 

Another acrylonitrile plant supplied by-product hydrogen cyanide to various other units. An inventory of 350,000 pounds of hydrogen cyanide was eliminated by having the other units draw directly from the acrylonitrile plant. This required considerable work to resolve many issues related to acrylonitrile purity and unit scheduling. 

This process does produce HCN as a by-product in small quantities. Puranik et al. (1990) report on work to develop an improved, more selective catalyst, and on coupling the ammoxidation process with a second reactor in which a subsequent oxycyanation reaction would convert the by-product HCN to acrylonitrile. 

Attachment of a basic amino group to the side chain leads to a compound with antiparkinsonian activity. Alkylation of the carbanion from phenylacetonitrile with 2-chlorotriethylamine affords the product, 36. Conjugate addition of the anion from this to acrylonitrile gives the glutarodinitrile (37). Partial hydrolysis of this in a mixture of sulfuric and acetic acid leads to phenglutarimide (38). ... 

A remarkably simple fused indole devoid of the traditional side chains is described as an antidepressant agent. Michael addition of the anion from indole ester 119 to acrylonitrile affords the cyanide 120. Selective... 

Redncdons of y-nitroketones yield cyclic nitrones, which undergo inter- and intramolecular cycloadthdon to various alkenes. The result of adthdon to acrylonitrile is shown in Eq. 8.43, in which a rruxnire of regio- and stereoisomers is formed. - ... 

Ammoxidation of propylene is considered under oxidation reactions because it is thought that a common allylic intermediate is formed in both the oxidation and ammoxidation of propylene to acrolein and to acrylonitrile, respectively. 

Ammoxidation of isobutylene to produce methacrylonitrile is a similar reaction to ammoxidation of propylene to acrylonitrile. However, the yield is low. 

Telescope the Process by Combining Stages. This has been done successfully in the conversion of propylene to acrylonitrile by direct ammoxidation rather than oxidation to acrolein followed by reaction with ammonia in a separate stage, as was described in the earlier patent literature. The oxychlorination of ethylene and HC1 directly to vinyl chloride monomer is another good example of the telescoping of stages to yield an economic process. 

Giese and Kretzschmar7j found the rate of addition of hexenyl radicals to methyl acrylate increased 2-fold between aqueous tetrahydrofuran and aqueous ethanol, Salikhov and Fischer74 reported that the rate constant for /-butyl radical addition to acrylonitrile increased 3.6-fold between tetradecane and acetonitrile. Bednarek et al75 found that the relative reactivity of S vs MMA towards phenyl radicals was ca 20% greater in ketone solvents than it was in aromatic solvents. 

Amines add very cleanly to acrylonitrile (19) and atalytic reduction of (18) gives TM (17). 

Lipases are the enzymes for which a number of examples of a promiscuous activity have been reported. Thus, in addition to their original activity comprising hydrolysis of lipids and, generally, catalysis of the hydrolysis or formation of carboxylic esters [107], lipases have been found to catalyze not only the carbon-nitrogen bond hydrolysis/formation (in this case, acting as proteases) but also the carbon-carbon bond-forming reactions. The first example of a lipase-catalyzed Michael addition to 2-(trifluoromethyl)propenoic acid was described as early as in 1986 [108]. Michael addition of secondary amines to acrylonitrile is up to 100-fold faster in the presence of various preparations of the hpase from Candida antariica (CAL-B) than in the absence of a biocatalyst (Scheme 5.20) [109]. 

Scheme 5.20 Lipase-catalyzed Michael addition of amines to acrylonitrile.

Benzyl bromide adds to acrylonitrile in the presence of CrCls/Mn and 4-tert-bu-tylpyridine in THF/H2O, via in situ formation of CrCl2, to afford 85% 4-phenylbu-tyronitrile 2128 and traces of dibenzyl [55]. If only catalytic amounts of CrCls are used, TCS 14 and isopropanol must be added [55] (Scheme 13.15). 

Figure 9.19. Secondary-ion mass spectrum of a promoted Fe-Sb oxide catalyst used for the selective oxidation of propylene and ammonia to acrylonitrile, showing the presence of Si, Cu, and Mo along with traces of alkali in the catalyst. [Reproduced from J.W. Niemantsverdriet, Spectres-200 gpy jfj Catalysis, 2" Edn.

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