the taste of organic(2)

if 67% nitrtic acid is used in 1:3 molar ratio in presence of vanadium as catalyst => adipic acid formed in 90% yield

if no catalyst used => adipic acid formed with yeild of 82%

also if u want to know the role of vanadium in the oxidation of cyclohexanol to adipic acid by nitric acid

here is it ...

The oxidation of cyclohexanol to adipic acid by nitric acid takes place by two routes. One of these, in which 2-nitro-2-nitrosocyclohexanone and the nitrolic acid are intermediates, is not influenced by the presence of vanadium(V). The other, involving cyclohexane-1,2-dione and its tautomer, only gives a significant amount of adipic acid if the metal ion is present. The dione and predione, a dimeric species which can be isolated from the system, appear to be in equilibrium with the monohydrate (. It is this last compound which is selectively oxidised by vanadium(V). The mono-enol is formed by slow tautomerisation of the dione and is selectively oxidised in the presence of vanadium(V) to glutaric acid. The mono-oxime appears to be the key intermediate linking the two routes.

i was looking for such a brilliant answer......well done eureka!!!!!!