Patent ID: 7635596

Claim:
A method for monitoring degradation of lubricating oils; said method comprising steps of: (a) adding to a lubricating oil at least one compound having formula (I) wherein R 1 and R 2 independently are hydrogen, hydroxy, OR 11 , amino or NR 11 R 12 ; R 3 and R 5 independently are alkyl, aryl, aralkyl, heteroalkyl or heterocyclic; R 4 and R 6 independently are hydrogen or alkyl; R 7 , R 8 , R 9 and R 10 independently are cyano, nitro, amide, carboxyl, ester, alkyl or hydrogen; R 11 is alkyl, aryl, aralkyl, heteroalkyl, heterocyclic or alkanoyl; R 12 is hydrogen or alkyl; provided that said at least one compound of formula (I) has at least one substituent selected from among cyano, nitro, hydroxy, hydroxyalkyl, amide, carboxyl, ester and unsaturated alkyl; (b) measuring a spectroscopic property of the oil to determine degradation of said at least one compound by comparing absorption intensity displayed by a cyano, nitro, hydroxyl, hydroxyalkyl, amide, carboxyl, ester or unsaturated alkyl substituent with absorption intensity of the cyano, nitro, hydroxy, hydroxyalkyl, amide, carboxyl, ester or unsaturated alkyl substituent when said at least one compound was first introduced into the lubricating oil, and determining a fraction of molecules containing the cyano, nitro, hydroxy, hydroxyalkyl, amide, carboxyl, ester or unsaturated alkyl substituent that have been degraded; and (c) correlating said fraction with degradation of the lubricating oil.