Photosubstitution-photoreduction mechanistic duality in the SET photoreactions of nitrophenyl ethers with amines. The role of the steps that follow the ET
作者:Miquel Mir、Jordi Marquet、Oriol Massot
DOI:10.1016/s0040-4020(99)00735-8
日期:1999.10
photoreduced by primary amines in water through a mechanism initiated by single electron transfer that is in direct competition with the single electron transfer photosubstitution mechanism (SNAr∗-SET). Our results indicate that the preferred pathway does not depend on the electron donor or proton donor ability of the amine. The key factor that determines the progress of the photoreaction is the structure
ion involve attack of the amine upon a triplet excited state of NVT.Mechanistic evidences indicate that the reaction with hydroxide ion is probably a SN23Ar* process whereas the reaction with piperidine involves a radical ion pair formed via electron transfer from the amine to a triplet excited state. Photoreactions. with primary amines involve attack of the amine upon a singlet excited state of NVT
4-硝基veratrole(NVT)被伯胺,哌啶和氢氧根离子光取代。伯胺和氢氧根离子导致相对于硝基的位置上的甲氧基取代,而哌啶将硝基上的甲氧基取代。哌啶和氢氧根离子的光反应涉及胺对NVT三重激发态的攻击。机理证据表明,与氢氧根离子的反应可能是S N 2 3 Ar *过程,而与哌啶的反应则涉及通过电子从胺转移到三重激发态。光反应。伯胺的反应涉及胺对NVT(S的单重激发态)的攻击N 2 1 Ar *工艺)。在亲核试剂电离势的考虑因素和基态供体-受体复合物形成能力的背景下讨论并证明了这些结果。
The search for new biochemical photoprobes. II. The nucleophilic photosubstitution of 2-fluoro-4-nitroanisole.
studied. The preparative results, the thermal stability of the photochemical substrate, and the limiting quantum yield values obtained from photoreactions with several nucleophiles suggest the possible usefulness of 2-fluoro-4-nitrophenyl ethers as biochemicalphotoprobes.
photosubstitutions of 2-fluoro-4-nitroanisole with several amines are studied from the preparative and the preliminary mechanistic points of view. The possible usefulness of this structure as biochemicalphotoprobe is discussed.
The photosubstitution of 2-fluoro-4-nitroanisole with n-hexylamine. Evidence of two different triplet excited states in a dual mechanistic pathway.
作者:Roser Pleixats、Jorge Marquet
DOI:10.1016/s0040-4020(01)86698-9
日期:1990.1
The photoreaction of 2-fluoro-4-nitroanisole with n-hexylamine gives rise to fluoride (major) and methoxy (minor) substitution. A continuous irradiation mechanistic study indicates that the first is produced through a SN23Ar* mechanism that Involves a π–π triplet excited state whereas the second is a consequence of n–π* triplet excited state chemistry via an electron transfer mechanism.
2-氟-4-硝基苯甲醚与正己胺的光反应产生氟(主要)和甲氧基(次要)取代。连续的辐射机理研究表明,第一个是通过S N 2 3 Ar *机理产生的,该机理涉及一个π-π三重激发态,而第二个是n-π*三重激发态化学反应通过电子转移机理产生的结果。