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Photoinduced reactions of chloranil with 1,1-diarylethenes and product photochemistry-intramolecular 总被引:1,自引:0,他引:1
Photoinduced reactions of chloranil (CA) with 1,1-diarylethenes 1 [(p-X-Ph)(2)C=CH(2), X = F, Cl, H, Me] in benzene afforded products 4-14, respectively, with the bicyclo[4.2.0]oct-3-ene-2,5-diones 4, the 6-diarylethenylcyclohexa-2,5-diene-1,4-diones 5, and 2,3,5, 6-tetrachlorohydroquinone 13 as the major primary products. The cyclobutane products 4 are formed via a triplet diradical intermediate without involvement of single electron transfer (SET) between the two reactants, while 5 is derived from a reaction sequence with initial SET interaction between (3)CA and the alkene. The 9-arylphenanthrene-1,4-diones 6 and its 10-hydroxy-derivatives 7 are secondary photochemical products derived from 5. The isomeric cage products 9-11 are formed from 4 via intramolecular benzene-alkene [2 + 2] (ortho-)photocycloadditions induced by the triplet excited enedione moiety. The relative amount of the two groups of products (4 and its secondary products 9-11 via non-SET route vs 5 and its secondary products 6, 7, 8, 12, and 14 via SET route) shows a rather regular change, with the ratio of non-SET route products gradually increasing with the increase in oxidation potential of the alkenes and in the positive free energy change for electron transfer (DeltaG(ET)) between (3)CA and the alkene, at the expense of the ratio of the products from the SET route. The competition between the SET and non-SET routes was also found to be drastically influenced by solvent polarity, with the SET pathways more favored in polar solvent. Photo-CIDNP investigations suggest the intermediacy of exciplexes or contact ion radical pairs in these reactions in benzene, while in acetonitrile, SET process led to the formation of CA(*)(-) and cation radical of the alkene in the form of solvent separated ion radical pairs and free ions. 相似文献
75.
Cai H Chen T Wang X Schultz AJ Koetzle TF Xue Z 《Chemical communications (Cambridge, England)》2002,(3):230-231
Reactions of Ta(NMe2)5 with D2SiR'Ph (R' = Me, Ph) were found to give a dideuteride eta 2-imine complex (Me2N)3Ta(mu-D)2(mu-N-eta 2-N,C-CH2NMe)Ta(NMe2)3(1-d2) through C-H activation of an amide ligand via beta-H abstraction, and the structure of 1 was confirmed by single crystal neutron and X-ray diffraction. 相似文献
76.
Studies on the Interaction of Beryllon Ш with Proteins by Voltammetric Technique and its Application 总被引:1,自引:0,他引:1
A new quantitative determination method of proteins using beryllon Ш by voltammetric technique was developed in this paper. In pH 3.5 Britton-Robinson (B-R) buffer solution, beryllon Ш can bind with human serum albumin (HSA) to form an electro-inactive supermolecular complex. Beryllon Ш has a well-defined voltammetric reduction peak at -0.38 V (vs. SCE) and the addition of protein in this solution can cause the decrease of the reductive peak current. Based on the decrease of the reduction peak current, a new electrochemical method for the determination of HSA was established with linear range of 1.0~40.0 mg/L and the detection limit of 1.0 mg/L. This method is further applied to the determination of real sample of healthy human serum. 相似文献
77.
交联助剂对PPC/NBR弹性体结构和性能的影响 总被引:2,自引:1,他引:2
研究了马来酸酐(MA)及异氰脲酸三烯丙酯(TAIC)对聚丙撑碳酸酯/丁腈橡胶共混弹性体结构和性能的影响,发出加入MA或TAIC能有效地改善交联网络;加入适量MA能显著改善共混弹性体热氧老化稳定性;加入TAIC使共混弹性体具有优良的高弹特性和力学性能。 相似文献
78.
氯磺化聚乙烯水解后是一种性能特异的离子交换膜。本文研究了低密度及高密度聚乙烯中空纤维氯磺化反应时间与交换容量之间的关系,并用红外光谱及广角X射线衍射法测定了氯磺化反应对聚乙烯晶体结构的影响。结果表明,氯磺化反应主要发生在聚乙烯的非晶区,最大交换容量及反应速度均与非晶区含量有关。反应对晶粒表面也有一定程度的侵蚀作用,随着交换容量的增加,结晶度下降,晶粒度减小。低密度及高密度聚乙烯的变化趋势相似,但前者比后者变化更显著。 相似文献
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Desulfurization of flue gas: SO(2) absorption by an ionic liquid 总被引:7,自引:0,他引:7