. ▁ ▁Similar ▁p ig ments ▁have ▁been ▁observed ▁in ▁qu in oline ▁de grad ation , ▁also ▁ow ing ▁to ▁transformation ▁of ▁met abol ites , ▁however ▁the ▁yellow ▁p ig ments ▁often ▁reported ▁in ▁de grad ation ▁of ▁many ▁py rid ine ▁sol vent s , ▁such ▁as ▁un subst it uted ▁py rid ine ▁or ▁p icol ine , ▁generally ▁result ▁from ▁over production ▁of ▁rib of la vin ▁in ▁the ▁presence ▁of ▁these ▁sol vent s . ▁ ▁Gener ally ▁speaking , ▁de grad ation ▁of ▁py rid ones , ▁di h ydro x yp y rid ines , ▁and ▁py rid ine car box y lic ▁ac ids ▁is ▁commonly ▁medi ated ▁by ▁o xygen ases , ▁whereas ▁de grad ation ▁of ▁py rid ine ▁sol vent s ▁often ▁is ▁not , ▁and ▁may ▁in ▁some ▁cases ▁involve ▁an ▁initial ▁re duct ive ▁step . ▁ ▁See ▁also ▁▁ 2 - Py rid one ▁( data ▁page ) ▁▁ 2 - P yr one ▁▁ 4 - Py rid one ▁The ▁ 5 - m eth yl - 2 - py rid one ▁is ▁used ▁to ▁make ▁pir fen id one . ▁ ▁References ▁ ▁General ▁references ▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁ ▁▁▁ ▁Category : C atal yst s ▁Category : 2 - Py rid ones ▁Category : L act ims <0x0A> </s> ▁Kl ara ▁H . ▁Coll itz ▁( born ▁ 3 0 ▁May ▁ 1 8 6 3 , ▁R he yd t ▁bei ▁M ön ch eng lad bach