2 vanillin => 1,2-bis(4-hydroxy-3-methoxyphenyl)ethylene + O2
2 vanillin => 1,2-bis(4-hydroxy-3-methoxyphenyl)ethylene + o2
2 vanillin => 1,2-bis(4-hydroxy-3-methoxyphenyl)ethylene + O2
2 vanillin => 1,2-bis(4-hydroxy-3-methoxyphenyl)ethylene + o2