X2Ge=Sn:(X=H,Me,F,Cl,Br,Ph,Ar…)are new species of chemistry.The cycloaddition reaction of X2Ge=Sn:is a new study field of stannylene chemistry.To explore the rules of cycloaddition reaction between X2Ge=Sn:and the symmetric p-bonded compounds,the cycloaddition reactions of Me2Ge=Sn:and ethylene were selected as model reactions in this paper,and the mechanism was investigated for the first time here using the MP2 theory together with the 6-311++G**basis set for C,H and Ge atoms and the LanL2dzbasis set for Sn atoms.From the potential energy profile,it could be predicted that the reaction has one dominant reaction channel.The reaction rule present is that the 5p unoccupied orbital of Sn in Me2Ge=Sn:and theπorbital of ethylene form a p→p donor–acceptor bond,resulting in an intermediate which,due to its instability,makes itself isomerize into a four-membered Ge-heterocyclic ring stannylene.Because the 5p unoccupied orbital of Sn atom in the four-membered Ge-heterocyclic ring stannylene and theπorbital of ethylene form a p→p donor-acceptor bond,the four-membered Ge-heterocyclic ring stannylene further combines with ethylene to get another intermediate.Because the Sn atom in this intermediate exhibits sp3 hybridization after transition state,the intermediate isomerizes to a Ge-heterocyclic spiro-Sn-heterocyclic ring compound.The research result indicates the laws of cycloaddition reaction between X2Ge=Sn:and the symmetricπ-bonded compounds.This study opens up a new research field for stannylene chemistry.
纯化牛血获得的高纯度血红蛋白,在不同条件下进行戊二醛交联反应得到聚合牛血红蛋白,应用SDS-PAGE对其分子量分布进行分析比较。利用葡萄糖-葡萄糖氧化酶系统和黄嘌呤-黄嘌呤氧化酶系统,研究氧化应激状态下过氧化氢和超氧化物对血红蛋白携氧性能的影响。结果表明,戊二醛交联血红蛋白反应的最佳条件为:溶液总体系5 m L、血红蛋白质量浓度82 g/L、磷酸钾缓冲液(p H=7.4)的浓度为0.1 mol/L、0.47 mol/L的赖氨酸0.2 m L、0.25 mol/L的冷戊二醛1.2 m L及在4℃下150 r/min摇荡24 h;葡萄糖-葡萄糖氧化酶和黄嘌呤-黄嘌呤氧化酶的存在会使血红蛋白被氧化,体系中存在抗氧化剂超氧化物歧化酶(SOD)和过氧化氢酶(CAT),会有效减弱血红蛋白氧化程度,提高其携氧性能。
