Three other commercial ε- processes avoid cyclohexanone oxime and therefore the Beckmann rearrangement. They are:
1. The Snia Viscosa cyclohexanecarboxylic acid process
2. The UCC caprolactone process
3. The Techni-Chem nitrocyclohexanone process

To 1:

The first step in the Snia Viscosa process is an air oxidation of toluene to benzoic acid at 160- 170°C and 8-10 bar over a Co catalyst with a yield of ca. 30%. The acid is then hydrogenated almost quantitatively to cyclohexanecarboxylic acid in the liquid phase over a Pd/C catalyst at 170°C and 10-17 bar.

The cyclohexanecarboxylic acid is then reacted with nitrosyl-sulfuric acid in oleum at temperatures up to 80 °C. The reaction apparently goes through formation of a mixed anhydride and several other intermediate steps to eliminate CO₂ and giveε-Caprolactam as the sulfate:

Processing of the acidic caprolactam solution takes place in the usual manner with NH₃. In a newer version, ε-caprolactam is extracted from the sulfuric acid solution with alkylphenols, and then stripped with H₂O.

Operated this way, the Snia Viscosa route can be a salt-free process. With a 50% conversion of cyclohexanecarboxylic acid, the selectivity to ε-caprolactam is 90%.

Two plants in Italy with a total capacity of 100000 tonnes per year and one 80000 tonne-per-year plant in the CIS use the Snia Viscosa process.

To 2:

In the UCC process, cyclohexanone is first oxidized to ε-caprolactone with peracetic acid at 50°C and atmospheric pressure. The selectivities are 90% (based on cyclohexanone) and 85-90% (based on peracetic acid). The ε-caprolactone is then reacted with NH₃ at 170 bar and 300-400°C to ε-caprolactam:

The selectivity for both steps is about 70%. The UCC process has been operating in a 25000 tonne-per-year plant since 1967. In 1972 the ammonolysis was discontinued, but the plant is still being used to manufacture ε-caprolactone.

Many firms have been working on similar processes, i. e., synthesis of ε-hydroxycaproic acid or ε-caprolactone intermediates.lnterox in England, for example, has been producing caprolactone since 1975, increasing their capacity to 10000 tonnes per year. Daicel in Japan also manufactures caprolactone.

To 3:

The advantage of the Techni-Chem process (USA) over all other processes is that no byproducts arc formed. In this process, cyclohexanone is acetylated with ketene/acetic anhydride to cyclohexenyl acetate, which is then nitrated to 2-nitrocyclohexanone with elimination of acetic acid. The hydrolytic ring opening leads to nitrocaproic acid which is thcn hydrogenated to ε-aminocaproic acid. This can then be converted into ε-caprolactam at 300°C and 100 bar:

This process has been practiced only at the pilot-plant scale.