Aminomethyl置于paraquat Dichloride体系中,化学反应生成亚甲基亚胺
参考文献:Glycine Decarboxylation: The Free Radical Mechanism
标题:Glycine Decarboxylation: The Free Radical Mechanism
摘要:Radiation Chemical Methods Were Used To Investigate The Reactions Of Glycine Anions,H2Nch2Co2-(Gly(-)),With (Oh)-O-.,(Ch3)(2)(Coh)-O-.,And (Ch3)-C-. Radicals. A Major And Most Significant Product From All Of These Processes Is Co2. Pulse-Radiolysis Revealed That The Initial Step In The (Oh)-O-.-Induced Mechanism Is Oxidation Of The Amino Group,Producing (+h2N.)-Ch2-Co2-And Hn.-Ch2-Co2-With Yields Of 63% And 37%,Respectively. The Amino Radical Cation,(+h2N.)-Ch2-Co2-,Suffers Fast (Less Than Or Equal To 100 Ns) Fragmentation Into Co2 + (Ch2Nh2)-C-.. The Other Primary Radical,Hn.-Ch2-Co2-,Can Also Be Converted Into The Decarboxylating (+h2N.)-Ch2-Co2-By Reaction With Proton Donors Such As Phosphate (H2Po4-/k = 7.4 X 10(7) M-1 S(-1),And Hpo42-/k = 2.5 X 10(5) M-1 S(-1)) Or The Glycine Zwitterion,Gly(+/-) (K = 3.9 X 10(5) M-1 S(-1)),But Only On A Much Longer (Typically Mu S To Ms) Time Scale (K Approximate To 4 X 10(5) M-1 S(-1)). Competitively,The Hn.-Ch2-Co2-Transforms Into A Carbon-Centered Radical H2N-(Ch)-H-.-Co2-Either By An Intramolecular 1,2-H-Atom Shift (K = (1.2 +/-1.0) X 10(3) S(-1)) Or By Bimolecular Reaction With Gly(-) (K = (3.0 +/-0.2) X 10(4) M-1 S(-1)). Both C-Centered Radicals,H2N-(Ch)-H-.-Co2-And (Ch2Nh2)-C-.,Are Reductants As Verified Through Their Reactions With Fe(Cn)(6)(3-) And Methyl Viologen (Mv2+) In Pulse-Radiolysis Experiments (K Approximate To 4 X 10(9) M-1 S(-1)). The Eventual Complete Transformation Of All Primary Radicals Into H2N-(Ch)-H-.-Co2-And (Ch2Nh2)-C-. Was Further Substantiated By Gamma-Radiolytic Reduction Of Fe(Cn)(6)(3-). In The Presence Of Suitable Electron Donors,The Hn.-Ch2-Co2-Radical Acts As An Oxidant. This Was Demonstrated Through Its Reaction With Hydroquinone (K = (7.4 +/-0.5) X 10(7) M-1 S(-1)).Although The C-Centered H2N-(Ch)-H-.-Co2-Radical Is Not Generated In A Direct H-Atom Abstraction By (Oh)-O-.,This Radical Appears To Be The Exclusive Product In The Reaction Of Gly(-) With (Ch3)(2)(Coh)-O-.,(Ch2Nh2)-C-.,And (Ch3)-C-. (K Approximate To 10(2) M-1 S(-1)). A Most Significant Finding Is That H2N-(Ch)-H-.-Co2-Can Be Converted Into The Decarboxylating N-Centered Radical Cation (+h2N.)-Ch2-Co2-By Reaction With Proton Donors Such As Gly(+/-) (K Approximate To 3 X 10(3) M-1 S(-1)) Or Phosphate And Thus Also Becomes A Source Of Co2. The (Ch2Nh2)-C-.-Induced Route Establishes,In Fact,A Chain Mechanism Which Could Be Proven Through Dose Rate Effect Experiments And Suppression Of The Chain Upon Addition Of Fe(Cn)(6)(3-) Or Mv2+ As A Scavenger For The Reducing Precursor Radicals. The Possible Initiation Of Amino Acid Decarboxylation By C-Centered Radicals And The Assistance Of Proton Donors At Various Stages Within The Overall Mechanism Are Considered To Be Of General Significance And Interest In Chemical And Biological Systems.
Doi:10.1021/ja9815428