vanillin + formaldehyde => 2-methoxy-4-vinylphenol + O2
vanillin + formaldehyde => 2-methoxy-4-vinylphenol + o2
vanillin + formaldehyde => 2-methoxy-4-vinylphenol + O2
vanillin + formaldehyde => 2-methoxy-4-vinylphenol + o2