The ab initio method has been used to study the 1-3 H transfer reaction on formamidine substituted by halogen. The calculation results show that the substituted halogen has two effects on the 1-3 H transfer reaction...The ab initio method has been used to study the 1-3 H transfer reaction on formamidine substituted by halogen. The calculation results show that the substituted halogen has two effects on the 1-3 H transfer reaction: decreasing the activation energy and stabilizing the C=N double bond owing to the conjugative effect of p-π-p of products and transition states.展开更多
In situ electron paramagnetic resonance(EPR)monitoring of the photocatalytic halogen atom transfer(XAT)reaction with organic amines has provided insights into the dynamic transformations of intermediates,including cat...In situ electron paramagnetic resonance(EPR)monitoring of the photocatalytic halogen atom transfer(XAT)reaction with organic amines has provided insights into the dynamic transformations of intermediates,including catalyst intermediate states,amine alkyl radicals,and the dehalogenation of halogenated hydrocarbons to form carbon-centered radicals.This approach facilitated the photocatalytic single-linear state oxygen-promoted halogen atom transfer quinoxalinone alkylation reaction.展开更多
Cross-linked poly（diallyldimethylammonium chloride） and its derivative copolymers were synthesized and used as phase transfer catalyst in the nucleophilic substitution reaction especially halogen exchange reactions....Cross-linked poly（diallyldimethylammonium chloride） and its derivative copolymers were synthesized and used as phase transfer catalyst in the nucleophilic substitution reaction especially halogen exchange reactions.In addition,the effect of hydrophilic-hydrophobic character of the polymers in the nucleophilic reactions was investigated.展开更多
With an adjusted model, we reconsider simple 1,2-dyotropic reactions with the introduction of a concept based on the intramolecular dynamics of a tetrahedron (van ’t Hoff modeling). In fact the dyotropic reactions ar...With an adjusted model, we reconsider simple 1,2-dyotropic reactions with the introduction of a concept based on the intramolecular dynamics of a tetrahedron (van ’t Hoff modeling). In fact the dyotropic reactions are strongly related to conversions originated from neighbouring group participation or anchimeric assistance, defined as the interaction of a center with a lone pair of electrons in an atom and the electrons present in aδor π bond. The researchful 1,2-dyotropic reactions, based on the 1,2-interchange of halogens, methyl and hydrogen taking place in a concerted fashion, are in competition with the two-step reaction in which the neighbouring group participation or anchimeric assistance comes to full expression by ionic dissociation of the other exchangeable (halogen) atom. As to be expected there is an essential difference between halogen or methyl exchange regarding the number of electrons participating in the transition state. This aspect becomes evident in the geometries of the corresponding transition state geometries. In this paper we refer to ab initio MO calculations and VB considerations. We consider the 1,2-halogen exchange as a combination of two SN2 reactions each containing four electrons. The van ’t Hoff dynamics appears a useful model in order to illustrate the computations in a straightforward manner.展开更多
In this paper,we overview beifely some of our key projects that had contridubted to modifyprevious author’s conclusions and put forward new viewpoints that are being underinvestigation.The novel ideas worth mentionin...In this paper,we overview beifely some of our key projects that had contridubted to modifyprevious author’s conclusions and put forward new viewpoints that are being underinvestigation.The novel ideas worth mentioning are the calculation of the sequence distributionon the copolymerization with a new version of probability suggested,the characterization of stepgrowth polymerization that indicates the MDW may not be continuous in theory,and after all,the Nylon 6 polymerization engineering exploitation where the concept of water activity is usedin place of concentration so as to extend the applicability’of the kinetic model proposed previous-ly.展开更多
An efficient chlorination reaction of in situ generated(β-diazo-α,α-difluoroethyl)phosphonates has been achieved with hydrochloric acid as a chlorine source under mild and operationally convenient conditions.The re...An efficient chlorination reaction of in situ generated(β-diazo-α,α-difluoroethyl)phosphonates has been achieved with hydrochloric acid as a chlorine source under mild and operationally convenient conditions.The reaction does not need any catalyst and tolerates a wide scope of substrates,which affords the(β-chlorodifluoroethyl)phosphonate products in good to excellent yields.This reaction represents the first example of the halogenation of difluoroalkyl diazo compounds,and also provides an easy way for the synthesis of difluoromethylenephosphonate-containing compounds.展开更多
Existing organic halide synthesis routes typically employ elemental halogens(X_(2),X=Cl or Br),leading to low atom economy and significant environmental pollution.In this work,we developed an atom efficient electrosyn...Existing organic halide synthesis routes typically employ elemental halogens(X_(2),X=Cl or Br),leading to low atom economy and significant environmental pollution.In this work,we developed an atom efficient electrosynthesis and separation strategy for halogenation reagents—N-chlorosuccinimide(NCS)and N-bromosuccinimide(NBS)—at high current densities.Faradic efficiency(FE)of 91.0%and 81.3%was achieved for NCS and NBS generation on RuO_(x)/TiO_(2)/Ti in a batch cell,respectively.Electrosynthesis of NCS likely involves both heterogeneous catalytic and homogeneous tandem pathways,while NBS is likely formed in a Langmuir-Hinshelwood mechanism with a proton-coupled electron transfer as the rate-determining step.A coupled continuous electrocatalytic synthesis and in situ separation setup was developed for the efficient production of NCS and NBS,which yielded 0.77 g of NCS in 12000 s and 0.81 g of NBS in 15000 s,both with relative purity exceeding 95%.The halogenation of acetone using NCS and NBS enabled gram-scale production of the key intermediate in organic synthesis,1-halogenacetone,with over 95%recovery of succinimide.展开更多
基金Supported by the Yunnan Provincial Science and Technology Department (2003A0003M)
文摘The ab initio method has been used to study the 1-3 H transfer reaction on formamidine substituted by halogen. The calculation results show that the substituted halogen has two effects on the 1-3 H transfer reaction: decreasing the activation energy and stabilizing the C=N double bond owing to the conjugative effect of p-π-p of products and transition states.
基金Project supported by the Domestic Visiting Fellows Program of Hangzhou Normal University(No.4095C5022521106)。
文摘In situ electron paramagnetic resonance(EPR)monitoring of the photocatalytic halogen atom transfer(XAT)reaction with organic amines has provided insights into the dynamic transformations of intermediates,including catalyst intermediate states,amine alkyl radicals,and the dehalogenation of halogenated hydrocarbons to form carbon-centered radicals.This approach facilitated the photocatalytic single-linear state oxygen-promoted halogen atom transfer quinoxalinone alkylation reaction.
文摘Cross-linked poly（diallyldimethylammonium chloride） and its derivative copolymers were synthesized and used as phase transfer catalyst in the nucleophilic substitution reaction especially halogen exchange reactions.In addition,the effect of hydrophilic-hydrophobic character of the polymers in the nucleophilic reactions was investigated.
文摘With an adjusted model, we reconsider simple 1,2-dyotropic reactions with the introduction of a concept based on the intramolecular dynamics of a tetrahedron (van ’t Hoff modeling). In fact the dyotropic reactions are strongly related to conversions originated from neighbouring group participation or anchimeric assistance, defined as the interaction of a center with a lone pair of electrons in an atom and the electrons present in aδor π bond. The researchful 1,2-dyotropic reactions, based on the 1,2-interchange of halogens, methyl and hydrogen taking place in a concerted fashion, are in competition with the two-step reaction in which the neighbouring group participation or anchimeric assistance comes to full expression by ionic dissociation of the other exchangeable (halogen) atom. As to be expected there is an essential difference between halogen or methyl exchange regarding the number of electrons participating in the transition state. This aspect becomes evident in the geometries of the corresponding transition state geometries. In this paper we refer to ab initio MO calculations and VB considerations. We consider the 1,2-halogen exchange as a combination of two SN2 reactions each containing four electrons. The van ’t Hoff dynamics appears a useful model in order to illustrate the computations in a straightforward manner.
文摘In this paper,we overview beifely some of our key projects that had contridubted to modifyprevious author’s conclusions and put forward new viewpoints that are being underinvestigation.The novel ideas worth mentioning are the calculation of the sequence distributionon the copolymerization with a new version of probability suggested,the characterization of stepgrowth polymerization that indicates the MDW may not be continuous in theory,and after all,the Nylon 6 polymerization engineering exploitation where the concept of water activity is usedin place of concentration so as to extend the applicability’of the kinetic model proposed previous-ly.
基金supports from the National Natural Science Foundation of China (No. 21761132021)German Research Foundation (No. RO362/74–1)Qin Lan project from Jiangsu Province for JLH is also acknowledged
文摘An efficient chlorination reaction of in situ generated(β-diazo-α,α-difluoroethyl)phosphonates has been achieved with hydrochloric acid as a chlorine source under mild and operationally convenient conditions.The reaction does not need any catalyst and tolerates a wide scope of substrates,which affords the(β-chlorodifluoroethyl)phosphonate products in good to excellent yields.This reaction represents the first example of the halogenation of difluoroalkyl diazo compounds,and also provides an easy way for the synthesis of difluoromethylenephosphonate-containing compounds.
文摘Existing organic halide synthesis routes typically employ elemental halogens(X_(2),X=Cl or Br),leading to low atom economy and significant environmental pollution.In this work,we developed an atom efficient electrosynthesis and separation strategy for halogenation reagents—N-chlorosuccinimide(NCS)and N-bromosuccinimide(NBS)—at high current densities.Faradic efficiency(FE)of 91.0%and 81.3%was achieved for NCS and NBS generation on RuO_(x)/TiO_(2)/Ti in a batch cell,respectively.Electrosynthesis of NCS likely involves both heterogeneous catalytic and homogeneous tandem pathways,while NBS is likely formed in a Langmuir-Hinshelwood mechanism with a proton-coupled electron transfer as the rate-determining step.A coupled continuous electrocatalytic synthesis and in situ separation setup was developed for the efficient production of NCS and NBS,which yielded 0.77 g of NCS in 12000 s and 0.81 g of NBS in 15000 s,both with relative purity exceeding 95%.The halogenation of acetone using NCS and NBS enabled gram-scale production of the key intermediate in organic synthesis,1-halogenacetone,with over 95%recovery of succinimide.
