A New Route to Lactam Precursors from Cycloalkanes: Direct Production of Nitrosocycloalkanes or Cycloalkanone Oximes by Using tert-Butyl Nitrite and N-Hydroxyphthalimide

摘要

The development of an innovative methodology for the production of bulk and commodity chemicals, in particular one that takes account of effects on the environment, becomes more and more important in industrial chemistry worldwide. ε-Caprolactam is one of the monomers most widely used for the production of nylon 6; the world production capacity of ε-caprolactam in 1998 was about 4.2 million tons. Currently, ε-caprolactam is produced by the following methods (Scheme 1): 1) Beckmann rearrangement of cyclohexanone oxime derived from cyclohexanone and hydroxylamine (Route A) or from cyclohexane and NOCl by the photonitrosation of cyclohexane (PNC) process (Route B), or 2) nitrosation of cyclohexane carboxylic acid with NOHSO_4 (Route C). Of these approaches, Route A is most often employed and accounts for about 70 % of the total production of ε-caprolactam worldwide. However, this method has several drawbacks. Cyclohexanone is supplied by the aerobic oxidation of cyclohexane, which leads to a mixture of cyclohexanone and cyclohexanol (K/A oil), but the conversion of cyclohexane must be kept at only 3-6 % to avoid the formation of further oxidation products such as adipic acid and glutaric acid. Another serious drawback of this method is the coproduction of a large amount of ammonium sulfate waste in both the hydroxylamine production and the Beckmann rearrangement processes.