β-取代卟啉及卟啉锰对氧化破坏的稳定性  

The Oxidative Destruction Stabilities of β-Substituted Porphyrins and Manganic Porphyrins

作　　者：唐渝[1] 张渊明[1] 岑颖洲[1] 

机构地区：[1]暨南大学化学系,广东广州510632

出　　处：《化学世界》2004年第10期515-518,共4页Chemical World

摘　　要：在假一级条件下,以亚碘酰苯为氧化剂,通过测定β-未取代的四苯基卟啉(TPP),以及不同β-取代的β-Cl8TPP、β-Br8TPP、β-Br4TPP、β-NO2TPP、β-(CH3)8TPP及其金属锰配合物的氧化破坏反应的表观动力学常数,获得了卟啉配体的稳定性顺序为TPP>β-(CH3)8TPP>β-Br8TPP>β-Cl8TPP>β-Br4TPP>β-NO2TPP,β位位阻越大相应的卟啉配体越稳定,并由此推导PhIO由β位进攻卟啉配体。β-取代锰卟啉的稳定性顺序为:Mn(β-Cl8TPP)Cl>Mn(β-Br8TPP)Cl>Mn(β-Br4TPP)Cl>Mn(β-NO2TPP)Cl>Mn(TPP)Cl>Mn[β-(CH3)8TPP]Cl,并与在催化氧化环己烷反应中的稳定性一致,β位吸电子作用越大相应的锰卟啉越稳定,并推导由氧化能力更强的高价金属-氧中间体以位阻较小的面对面方式进攻β-取代锰卟啉。Using iodosobenzene as oxidant and assuming the reaction to be pseudo first order, the rate constants of oxidative destruction of β-unsubstituted tetraphenylporphyrins (TPP), β-Cl_8TPP,β-Br_8TPP,β-Br_4TPP,β-NO_2TPP,β-(CH_3)_8TPP and their manganic complexes were determined. The stability of the porphyrin ligands and their manganic complexes was compared with respect to their rate constants. The stability sequence of the porphyrin ligands was TPP>β-(CH_3)_8TPP>β-Br_8TPP>β-Cl_8TPP>β-NO_2TPP. The porphyrin ligand with bigger β steric hindrance and better conjugation was more stable, therefore the porphyrin ligands might be attacked at β position by iodosobenzene during reaction. The stability consequence of the manganic porphyrins was Mn(β-Cl_8TPP)Cl>Mn(β-Br_8TPP)Cl>Mn(β-Br_4TPP)Cl>Mn(β-NO_2TPP)Cl>Mn(TPP)Cl>Mn[β-(CH_3)_8TPP]Cl, same to that in catalyzed oxidation of cyclohexane, showing that the stronger the electrophilic at β position the more stable the manganic porphyrin. It was suggested that manganic porphyrins could be attacked by more oxidative high valent metal-oxygen intermediates face to face with less steric hindranc.

关 键 词：β-取代卟啉 β-取代锰卟啉 氧化 稳定性 

分 类 号：O621.16[理学—有机化学]