Generation of Chloropolyfluoromethylene-1-indanyl Cations and Their Isomerization into Chloropolyfluoromethylindenyl Cations

Chlorooctafluoro-3-methylene-1-indanyl, 3-(chlorofluoromethylene)heptafluoro-1-indanyl, and 2- and 3-(dichloromethylene)heptafluoro-1-indanyl cations were generated from the corresponding dihalomethyleneindans in the system SbF₅-SO₂ClF. Isomerization of these cations yields thermodynamically more stable polyfluoromethylindenyl cations with chlorine atoms in the five-membered ring.     

带功能基的全氟烷基乙烯基醚的研究——4.四氟乙烯与全氟-3,6-二氧杂-4-甲基-△~7-辛基磺酰氟溶液共聚反应单体竞聚率的测定

在乙烯-四氟乙烯溶液共聚合体系研究中,我们曾编制了一个简易的计算机程序,用于测定二种单体的共聚竞聚率,这一方法计算方便,而且可以避免原先作图法中的误差,结果较为可靠。前文我们报道了四氟乙烯与两个新的全氟烷基乙烯基醚的共聚合反应,并对其中一个新单体——7,7-二氯-3-氧杂-全氟庚烯-1——与四氟乙烯的共聚进行了单体竞聚率的测定。结果表明,这一新的含氟烯醚单体的聚合活性较其它已有报道的同类单体大。为了验证这一     

Reaction of Perfluoro-1-methylbenzocyclobutene with Pentafluorobenzene in SbF5 Medium

A reaction of perfluoro-1-methylbenzocyclobutene with pentafluorobenzene in SbF₅ medium followed by treating the reaction mixture with water gave rise to perfluoro-1-methyl-1-phenylbenzocyclobutene, perfluoro-1-methyl-2-phenylbenzocyclobutene, 2-hydroxyperfluoro-1-methyl-2-phenylbenzocyclobutene, and also to small amounts of 1-(2-trifluoromethyltetrafluorophenyl)-1-pentafluorophenyl-2,2,2-trifluoroethane, and perfluoro-1-(2-methylphenyl)-1-phenylethylene. In a crystal of (E)-2-hydroxyperfluoro-1-methyl-2-phenylbenzocyclobutene for a dimer molecular pair a -stacking interaction between pentafluorophenyl groups was found.     

A Germacyclopropene with Electronegative Groups at the Ring Carbon Atoms [1]

The reaction of tetrakis(2‐tert‐butyl‐4, 5, 6‐trimethylphenyl)digermene, which dissociates into germylene molecules in solution, with hexafluorobut‐2‐yne furnishes the corresponding germacyclopropene 3 by a [1+2] cycloaddition of the germylene to the C≡C triple bond. The X‐ray structure analysis of 3 reveals a short C=C double bond length of 132.4(5) pm and an acute C—Ge—C bond angle of 39.93(14)°.     

Generation and Characterization of Psoralen Radical Cations

Abstract— Radical cations of psoralen, 8-methoxypsoralen(8-MOP) and 5-methoxypsoralen have been generated by photosensitized electron transfer in acetonitrile and aqueous buffer/acetonitrile (1:1) and have absorption maxima at 600, 650 and 550 nm, respectively. The radical cations have lifetimes of 5 p.s under these conditions, are unreactive toward oxygen and show behavior typical of ar-ylalkene radical cations in their reactivity toward nucle-ophiles and the precursor psoralens. Direct 355 nm excitation of 8-MOP in aqueous buffer at physiological pH results in monophotonic photoionization to give 8-MOP_*+ with a quantum yield of 0.015.The 8-MOP_*+ reacts with both guanosine and adenosine mononucleotides ( k = 2.5 times 10₉ and 3.4 times 10₇ M_-1 s₁, respectively) via electron transfer to give the purine radical cations, but does not react with pyrimidine mononucleotides. These results suggest that reactions of psoralen radical cations generated by electron transfer or photoionization may be involved in psoralen/UVA therapy.     

有机正离子自由基的产生及其结构研究的进展

本文介绍了产生正离子自由基的方法,对正离子自由基的结构特点作了详细的讨论。     

Attempts at Solvolytic Generation of Phenyl Cations

New substrates and reaction conditions which may be expected to yield phenyl cation intermediates have been investigated. The approaches used were: (a) solvolysis of PhX in fluorinated alcohols, where X = ? N (O) = NOTs (tosyloxyazoxy), ? N (O) = NONf (Nf = C₄F₉SO) and ? OSO₂\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm N}\limits^{\rm + } $\end{document} (CH₃)₃ōTf (Tf=CF₃SO); (b) solvolysis of ArBr, PhOTf and PhOSO₂\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm N}\limits^{\rm + } $\end{document}(CH₃)₃ōTf (phenyl ‘betylate triflate’) in super-acid solvents (FSO₃H · SbF₅, SbF₅, AgSbF₆). Analysis of the product mixtures provided no evidence for the intermediacy of phenyl cations as a major pathway in any of the reactions. This result is remarkable, since the ‘betylate’, for example, is a better leaving group by a factor of at least 10⁵ than the ‘super’ leaving group triflate in the solvolysis of alkyl sulfonates. These results are a further indication of the extremely low stability of phenyl cations, as well as of the very special properties of the nitrogen leaving group in arenediazonium ions.     

Reactions of 1-Cyanoimidazole and 1-Cyanobenzimidazole with Aliphatic Alcohols

Alkyl imidazole-1-carboximidates and alkyl benzimidazole-1-carboximidates were synthesized by reaction of 1-cyanoimidazole and 1-cyanobenzimidazole with aliphatic alcohols. The reaction time and the product yield depend on the structure of the alcohol.     

Synthesis and Properties of Perfluoroalkyl Groups Containing Double Four-Ring Spherosilicate (Siloxysilsesquioxane) Precursors

Organically modified cage-like double four-ring spherosilicates have received considerable interest in the construction of nanosized hybrid materials, as well as building units for structural well-defined polymers. This group is extended by perfluoroalkyl ligands containing spherosilicates, synthesized by addition reaction of the octahydridodimethylsiloxyoctasilsesquioxane [H(CH₃)₂Si]₈Si₈O₂₀ and heptadecafluorodecyl methacrylate. The resultant liquid spherosilicate substituted with eight terminal perfluoroalkyl groups was characterized by ²⁹Si and ¹³C NMR spectroscopies and MALDI Time-of-Flight mass spectrometry. Partial substitution of perfluoroalkyl ligands by trimethoxysilyl containing groups provides condensable precursors for the synthesis of hydrophobic and oleophobic materials via the sol-gel process. This new spherosilicate, carrying on average four perfluoroalkyl groups and four trimethoxysilyl groups shows better hydrophobic and oleophobic properties compared with commonly used perfluoroalkyltrialkoxysilanes under identical concentration of perfluoroalkyl chains. In addition a comprehensive literature survey is given on structural well characterized, organically modified cage-like double four-ring spherosilicates.     

脂肪型超支化聚酯的端基改性研究

近年来 ,超支化聚合物以其独特的结构和性能而受到广泛的重视 ,已成为 2 1世纪高分子科学研究的重要方向[1～ 4 ] .超支化聚合物通常是通过 AB2 型单体的缩聚来合成的 ,由于超支化聚酯的单体容易合成 ,因此 ,有关超支化聚酯的研究最为深入 .目前所报道的脂肪型超支化聚酯都是以 2 ,2 -二甲醇基丙酸为原料来合成的 ,Malstrom等 [5～ 7]系统研究了该聚合物的合成及结构 .最近 ,Johansson[8]采用丙烯酰氯对该聚合物端基改性 ,获得了可用于紫外光固化的涂料 ,但是所采用的合成及提纯方法都很复杂 ,并且需要很长的反应时间 .本文采用一种新的…     

Comparison of the Retention of Aliphatic Hydrocarbons with Polar Groups in RP-HPLC Systems with Different Modifiers of the Binary Eluent

The retention of aliphatic hydrocarbons with polar groups has been compared in respect to the separation selectivity changes in reversed-phase high-performance liquid chromatography with C18 stationary phase type and binary water eluent composed of methanol, acetonitrile, or tetrahydrofuran as modifiers. The changes in separation selectivity when one modifier is replaced by another in the eluent is explained, taking into consideration molecular interactions of the solutes with components of the stationary phase region, i.e., extracted modifier, and ordering of the stationary phase by the modifier.     

Comparison of the Retention of Aliphatic Hydrocarbons with Polar Groups in RP-HPLC Systems with Different Modifiers of the Binary Eluent

The retention of aliphatic hydrocarbons with polar groups has been compared in respect to the separation selectivity changes in reversed-phase high-performance liquid chromatography with C18 stationary phase type and binary water eluent composed of methanol, acetonitrile, or tetrahydrofuran as modifiers. The changes in separation selectivity when one modifier is replaced by another in the eluent is explained, taking into consideration molecular interactions of the solutes with components of the stationary phase region, i.e., extracted modifier, and ordering of the stationary phase by the modifier.

     

Perfluoro-1-(butylimino)butyl isothiocyanate. Synthesis and reaction with n-propylamine

The reaction of perfluoro-5-azanon-4-ene with KSCN in an aprotic dipolar solvent provides perfluoro-1-(butylimino)butyl isothiocyanate. The latter was reacted with n-propylamine in the presence of triethylamine to obtain fluoro-substituted derivatives of thiourea, heptafluoropropionic acid, and 1,3,5-thiadiazine.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 10, 2004, pp. 1655–1658.Original Russian Text Copyright © 2004 by Furin, Zhuzhgov.This revised version was published online in April 2005 with a corrected cover date.     

Crosslinked Polystyrene Beads Modified with Sulfonyl Groups and Their Application in Aromatic/Aliphatic Hydrocarbons Separation

The separation of aromatic hydrocarbons from aromatic/aliphatic mixtures was investigated with cross- linked polystyrene（CPS） beads modified with sulfonyl groups. Three sulfonating agents, i.e. benzenesulfonyl chlo- ride（BsCl）, 4-toluene sulfonyl chloride（TsC1） and methanesulfonyl chloride（MsC1） were used to prepare sulfonyl CPS beads by Friedel-Crafts reaction. The CPS beads modified with BsC1 exhibited higher sulfonation rate than those modified with MsC1 and TsCI and obtained optimum selectivity in the experiments of toluene/n-heptane separation. Further separation tests with various other aromatic/aliphatic mixtures were carried out at an initial aromatic concen- tration of 13%（mass fraction） with the results showing that the modified beads have preferential selectivity for aro- matic hydrocarbons in all aromatic/aliphatic mixtures, and especially a separation factor of 8.21 and a swelling ratio of 30% for toluene/cyclohexane system. The thermal stability and regeneration test indicate that the used polystyrene beads can be recovered through heat-drying and reused effectively.     

Photosynthesis of Tetrahydroprotoberberines with Electron withdrawing Groups on Ring D

Althoughmanymethodshavesofarbeendevelopedforthesynthesisoftetrahydroprotoberberinesl'2,mostofthemareonlysuitableforthepreparationofthecompoundswithhydroxyoralkoxylgroupsonthebenzeneringsandcannotbeusedtosynthesizecompoundswithelectron-withdrawinggroupsonthebenzenemoieties.Infact,thepresenceofanelectron-withdrawinggrouponthearomaticringspreventtheringBorCclosureundertheclassicalreactionconditions3.Lenzanhasreportedthesynthesisofseveraltetrahydroprotoberberineswithmethoxyandmethylenedioxygroupso…     

Synthesis and Characterization of Novel Aliphatic Polycarbonates Bearing Pendant Allyl Ether Groups

To fulfill the diverse requirements in surgery and medicine, biomedical polymers have been drawing interests and attentions increasingly since the last decade1. In these fields, aliphatic carbonates have been proved to be a kind of material with excellent…