Oxides picoline ammoxidation

Reddy, B.N., Reddy, B.M. and Subrahmanyam, M. (1991) Dispersion and 3-picoline ammoxidation investigation of vanadium oxide/ aluminum oxide (V205/a-A1203) catalysts. Journal of the Chemical Society, Faraday Transactions, 87 (10), 1649-55. 

Nicotinonitrile is a precursor to nicotinic acid (Niacin) and nicotinamide, both of which are important B-complex vitamins. High selectivities to nicotinonitrile by ammoxidation of 3-picoline are possible with a variety of supported and promoted vanadium oxide catalysts. Particularly effective is V2O5 supported on titania. Merck Co., Inc., U.S.A. disclosed the use of V205/Ti02 catalysts promoted with M0O3, P2O5, and MnS04 for 3-picoline ammoxidation. The reaction was conducted at a relatively low temperature for ammoxidation in order to... 

An economically advantaged alternative to 3-picoline is 2-methyl-5-ethyl pyridine (MEP), which is a less expensive and more readily available feedstock. MEP is thus a preferred starting material for producing nicotinic acid whether by a direct oxidation or ammoxidation route. For direct conversion of MEP to nicotinonitrile, an added requirement of the catalyst and process is the dealkylation that must occur concurrently with the selective ammoxidation reaction. 

Nicotinic acid and nicotinamide, members of the vitamin B group and used as additives for flour and bread enrichment, and as animal feed additive among other applications, are made to the extent of 24 million pounds (nearly 11 million kilograms) per year throughout the world. Nicotinic acid (pyridine-3-caiboxylic acid), also called niacin, has many uses. See also Niacin. Nicotinic acid is made by the oxidation of 3-picolme or 2-mcthyl-5-cthylpyridine (the isocinchomcnc acid produced is partially deearboxylated). Alternatively, quinoline (the intermediate quinolinic acid) is partially deearboxylated with sulfuric add in the presence of selenium dioxide at about 300° C or with nitric acid, or by electrochemical oxidation. Nicotinic acid also can be made from 3-picoline by catalytic ammoxidation to 3-cyanopyridine, followed by hydrolysis. 

A new route to prepare nicotinic acid starts from 2-methylglutaronitrile, a major side-product in the adiponitrile process and, as such, a readily available starting-material. It is easily hydrogenated to 2-methylpentanediamine, which is then condensed to methyl piperidine and dehydrogenated to 3-picoline. The gas-phase ammoxidation of the latter to cyanopyridine is followed by hydrolysis to either nicotinamide or nicotinic acid (Scheme 20.4). The cyanopyridine route for the production of nicotinic acid has the advantage of a significantly better selectivity with respect to the direct oxidation route from 3-picoline owing to the easy decar-... 

Other examples found in the literature can be interpreted in the same way. In the ammoxidation of 3-picoline (81) on N (rutile), the maximum activity and selectivity are obtained in nearly the same composition range as for oxidation of o-xylene The catalyst was prepared by heating V O... 

Activity measurements. The measurements were performed at atmospheric pressure in a glass reactor. A thermocouple was positioned in the center of the reactor. In the ammoxidation of 3-picoline, the inlet reaction mixture was admitted at a rate of 32 liters/hr and contained 232-254 moles of air, 13-14 moles of ammonia, and 56-62 moles of water vapor for each mole of 3-picoline. The reaction was usually performed in the temperature interval 300-400 C. In the oxidation of MEP (2-methyl-5-ethylpyridlne) the molar ratios of O /MEP and steam/MEP were 75 and 175 respectively, and the space velocity was 7000 h. In ammoxidation studies prereduced catalysts were used and the measurements extrapolated in time to give data at the start of the reaction. In oxidation studies unreduced catalysts were used and the data were obtained at the steady state. 

Reddy, B.M., Kumar, M.V., and Manohar, B. Vanadium phosphorus oxide catalysts for ammoxidation of 3-picoline to nicotinonitrile and 2-methylpyrazine to 2-cyanopyrazine. In Catalysis of Organic Reactions, Scaros, M.G. Prunier, M.L., Eds. Marcel Dekker New York, 1995 pp. 487 91. 

Besides ammoxidation, 2- and 3Ps are also oxidized to the corresponding aldehydes using fixed-bed reaetors. These reactions run on a much smaller commercial scale (Raschig GmbH, Germany). In addition, picolines can be oxidized further to the corresponding acids as already mentioned above [e.g., 23]. Several companies have made annoimcements of their intentions to build plants for the catalytic vapor-phase conversion of 3-picoline towards niacin. 

In addition, some kinetic studies on the oxidative ammonolysis of 2-picoline using V-Sn/TiOj catalysts were reported [34]. The majority of work on this particular reaction was carried out by Russian researchers and in particular Suvorov s group [35]. It is also noteworthy that most of their results were published in Russian journals [e.g., 36]. Moreover, VPO catalysts (e.g., a-VOPO phase) were also applied by our group for the ammoxidation of three isomeric picolines to their corresponding cyanopyridines [3]. 

Kineties and mechanism of the vapor-phase ammoxidation of 3P was reported in mid 1970s by Prasad and Kar [62]. Radheshyam et al. [63] also reported kinetic studies and mechanism of the ammoxidation of 3P over V2O5/ ZrOj catalysts in a differential flow reactor in the temperature range from 300 10°C. They claimed from their kinetics studies that the meehanism of the reaction is of the Redox type and the rate equation dedueed assuming a steady state involves a three-stage oxidation-reduetion proeess dming the conversion of 3-picoline to 3CP. Based on that a tentative mechanism of the process has been proposed. 

Narayana, K. V, Venugopal, A., Rama Rao, K. S., Venkat Rao, V, Khaja Masthan, S., and Kanta Rao, P. Ammoxidation of 3-picoline over V O TiOj (anatase) system I. Relationship between ammoxidation activity and oxidation state of vanadium. Appl CatalA 150,269-278 (1997). 

Andersson, A., Bovin, J. O., and Walter, P. Ammoxidation of 3-picoline An activity and high-resolution electron microscopic investigation of vanadium oxide catalysts. J Catal 9S, 204-220(1986). 

Martin, A., Kalevaru, V. N., Lticke, B., and Bruckner, A. Deactivation and oxidative regeneration of VTiShSiO catalyst for ammoxidation of 3-picoline to nicotinonitrile. Appl CatalA 335, 196-203 (2008). 

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