Acrylonitrile hydration

An enzymatic acrylonitrile hydration was first patented in 1981 8nitrile hydratases of different origin have been shown to be able to convert acrylonitrile into acrylamide. However, a major problem associated with biocatalysis for production of acrylonitrile is the short half-life of the enzyme due to substrate and product inhibition. Acrylonitrile is a strong alkylating agent which reacts by Michael addition with the sulfhydryl groups of proteins f 8, 69L... 

Nitrile hydratases (NHases) catalyze the hydration of organic nitriles to amides under very benign reaction conditions (neutral aqueous environment and room temperature) and therefore offer a chemoselective alternative to classical approaches, where functional group compatibility is often limited due to the harsh acidic or basic solutions used [1], Starting with their application in acrylamide production [2,3], this enzyme class is one of the most prominent in industrial processes with respect to production volume (>3 X 10 kg/a for acrylonitrile hydration) [4]. Hence, Lonza (Switzerland) uses a nitrile hydratase to convert 3-cyanopyridine into nicotinamide (6 X 10 tons/year). Very recently, a one-pot industrial protocol for the synthesis of a chiral intermediate for dlastatin was published that employed a nitrile hydratease/amidase approach [5],... 

The current routes to acrylamide are based on the hydration of inexpensive and readily available acrylonitrile [107-13-1] (C3H3N, 2-propenenittile, vinyl cyanide, VCN, or cyanoethene) (see Acrylonitrile). For many years the principal process for making acrylamide was a reaction of acrylonitrile with H2SO4 H2O followed by separation of the product from its sulfate salt using a base neutralization or an ion exclusion column (68). 

The heat of hydration is approximately —70 kj /mol (—17 kcal/mol). This process usually produces no waste streams, but if the acrylonitrile feed contains other nitrile impurities, they will be converted to the corresponding amides. Another reaction that is prone to take place is the hydrolysis of acrylamide to acryhc acid and ammonia. However, this impurity can usually be kept at very low concentrations. American Cyanamid uses a similar process ia both the United States and Europe, which provides for their own needs and for sales to the merchant market. 

Currently, acrylamide is produced by the hydration of acrylonitrile in the presence of copper-based catalysts. 

Acetylene, clathrate in hydroquinone, 7 hydrate thermodynamic data and lattice constants, 8 Acrylamides, polymerization of, 181 Acrylonitrile, 155 Activity coefficients, 125... 

There are two pathways for the degradation of nitriles (a) direct formation of carboxylic acids by the activity of a nitrilase, for example, in Bacillus sp. strain OxB-1 and P. syringae B728a (b) hydration to amides followed by hydrolysis, for example, in P. chlororaphis (Oinuma et al. 2003). The monomer acrylonitrile occurs in wastewater from the production of polyacrylonitrile (PAN), and is hydrolyzed by bacteria to acrylate by the combined activity of a nitrilase (hydratase) and an amidase. Acrylate is then degraded by hydration to either lactate or P-hydroxypropionate. The nitrilase or amidase is also capable of hydrolyzing the nitrile group in a number of other nitriles (Robertson et al. 2004) including PAN (Tauber et al. 2000). 

A preliminary idea about the acceleration effect of the Pd atoms in the surface on the hydration of acrylonitrile is shown schematically in Figure 14. 

Figure 14. Schematic diagram of the acceleration effect of Pd on the hydration of acrylonitrile. (Reprinted from Ref [73], 1994, with permission from Wiley-VCH.)...

CuPd Hydration Acrylonitrile Acrylamide Higher than Cu-NP 100% [71-73]... 

Some Pt complexes bearing electron-donating phosphines can also catalyze the hydration of the C=C double bond of acrylonitrile or crotonitrile and yielded P-hy-droxypropionitrile or P-hydroxybutyronitrile respectively besides the corresponding amide (Eq. 6.38) [22, 75], Among the platinum phosphine complexes examined, [Pt(PEt3)3] (26a), carrying less bulky ligands, was the most effective for the hydration of the olefmic bond. The present catalyst system was ineffective for hydration of other olefins, however. 

There is a possibiUty that (hydroxymethyl)phosphines might be catalyzing hydration of activated olefinic moieties in lignin. The Michael addition reaction shown in eq. (6a) is catalyzed by 5% THP in water at ambient conditions, with 70% conversion of the acrylonitrile no such reaction is seen with aciyhc acid or the methyl ester, but analogous hydromethoxylation of these compounds is seen in MeOH (42) (eq. (6b), R = H or Me). There is a report on similar catalytic use of tiialkylphosphines, which, like THP, are strong nucleophiles (43). 

Partial hydrolysis of nitrile gives amides. Conventionally, such reactions occur under strongly basic or acidic conditions.42 A broad range of amides are accessed in excellent yields by hydration of the corresponding nitriles in water and in the presence of the supported ruthenium catalyst Ru(0H)x/A1203 (Eq. 9.19).43 The conversion of acrylonitrile into acrylamide has been achieved in a quantitative yield with better than 99% selectivity. The catalyst was reused without loss of catalytic activity and selectivity. This conversion has important industrial applications. 

In the late stage of work up of a sample prepared from acrylonitrile and hydrazine hydrate and stripped of water by a procedure involving dichloromethane, the distillation flask pressurised and burst, shattering the front of the fume cupboard. Previously, slight pressurisation had once been observed. Involving both a nitrile and a hydrazino moiety, this molecule cannot be thermodynamically stable but it has not given previous problems. 

Uses Manufacture of acrylonitrile, hydrazine hydrate, hydrogen cyanide, nitric acid, sodium carbonate, urethane, explosives, synthetic fibers, fertilizers refrigerant condensation catalyst dyeing neutralizing agent synthetic fibers latex preservative fuel cells, rocket fuel nitrocellulose nitroparaffins ethylenediamine, melamine sulfite cooking liquors developing diazo films yeast nutrient. 

Specific examples of RWA are further described. Raney copper precursor with a small amount of Pd was prepared by this process. Rapid solidification was effective in keeping most of the added Pd dissolved in the precursor. The specific surface area of the leached specimen increased by about 3 times in comparison with that of ordinary Raney copper catalyst. The conversion from acrylonitrile to acrylamide by the hydration reaction was about 60%, or more than 20% higher than that from ordinary Raney copper catalyst. In case of Ti or V addition, the conversion increased to 70-80%. Rapid solidification was quite effective in decreasing the defect rate of Raney catalysts from some precursors. The potential for design of new catalysts may be widely extended by rapid solidification. 

Propene is used as a starting material for numerous other compounds. Chief among these are isopropyl alcohol, acrylonitrile, and propylene oxide. Isopropyl alcohol results from the hydration of propylene during cracking and is the primary chemical derived from propylene. Isopropyl alcohol is used as a solvent, antifreeze, and as rubbing alcohol, but its major use is for the production of acetone. Acrylonitrile is used primarily as a monomer in the production of acrylic fibers. Polymerized acrylonitrile fibers are produced under the trade names such as Orion (DuPont) and Acrilan (Monsanto). Acrylonitrile is also a reactant in the synthesis of dyes, pharmaceuticals, synthetic rubber, and resins. Acrylonitrile production occurs primarily through ammoxidation of propylene CH3- CH = CH2 + NH3 + 1.5 02—> CH2 = CH - C = N + 3 H20. 

Jensen, C.M. and Trogler, W.C. (1986) Kinetics and mechanism of nitrile hydration catalyzed by unhindered hydridobis(phosphine)platinum(ll) complexes. Regioselective hydration of acrylonitrile. J. Am. Chem. Soc., 108, 723-729. 

The current routes to acrylamide are based on the hydration of inexpensive and readily available acrylonitrile (C3H3N, 2-propenenitnle, vinyl cyanide, VCN, 01 cyanoethene) See also Acrylonitrile. 

In addition to OH , other nucleophiles such as BH4 ,318 CN-319,320 and N3-321 also add at the nitrile carbon of cobalt(III)-nitrile complexes at rates which are = 104 times those of the corresponding reactions of the free ligands. Catalysis by C032 in the hydration of [(NH3)5RuNCMe]3+,316 and of the acrylonitrile complex [(NH3)5CoNCCH=CH2]3+,322 has been observed. In the latter complex, a direct nucleophilic pathway results in the incorporation of oxygen from C032 into the amide product with elimination of C02. 

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