Process for the production of 2-aryl-2H-benzotriazoles
A process for the production of 2-aryl-2H-benzotriazoles comprises reducing and cyclizing the corresponding o-nitroazobenzenes with hydrogen at a temperature in the range of about 20° C. to about 100° C. and at a pressure in the range of about 15 psia (1 atmosphere) to about 1000 psia (66 atmospheres) in an alkaline medium at a pH over 10 in the presence of a nickel catalyst, preferably molybdenum-promoted Raney nickel. High yields of pure product are obtained directly with a concomitant reduction of undesired by-product and a reduction in effluent pollution problems.
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(2008/06/13)
Process for the production of 2-aryl-2H-benzotriazoles
A process for the production of 2-aryl-2H-benzotriazoles comprises reducing and cyclizing the corresponding o-nitroazobenzenes with carbon monoxide at a temperature in the range of about 20° C. to about 150° C. and at a pressure in the range of about 15 psia (1 atmosphere) to about 1000 psia (66 atmospheres) in an alkaline medium at a pH over 10 in the presence of a copper-amine complex catalyst. High yields of pure product are obtained with a concomitant reduction of undesired by-products and a reduction in effluent pollution problems.
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(2008/06/13)
Process for the production of 2-aryl-2H-benzotriazoles
An improved process for the production of 2-aryl-2H-benzotriazoles by the reduction of o-nitroazobenzene intermediates with zinc in alkaline medium comprises employing a ratio of moles of alkali to moles of o-nitroazobenzene intermediate in the range of 0.2-1.7/1 in the presence of less than 150 ppm of iron based on zinc used. The improved process results in higher yields of high purity products with a concomitant reduction in the amount of undesired cleavage amine by-products and a reduction in effluent pollution problems. The process is carried out in a polar/non-polar solvent mixture.
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(2008/06/13)
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