The reactions of perfluorinated α- and β-alkoxyradicals with hydrogen chloride, chlorine and fluorine

The kinetics of the reactions of the macroradicals R_f′OCF₂ (I) and R_f′OCF₂CF₂ (II) with HCl, Cl₂ and F₂ have been studied in the liquid phase, being R_f′ a poly(oxydifluoromethylene-oxytetrafluoroethylene) chain with average molecular weight of about 10⁴ Da. Radical (I) showed a higher reactivity compared to radical (II) with all the three radical transfer agents.In case of HCl the activation energy for the reaction:

     

Chemistry in microstructured reactors

The application of microstructured reactors in the chemical process industry has gained significant importance in recent years. Companies that offer not only microstructured reactors, but also entire chemical process plants and services relating to them, are already in existence. In addition, many institutes and universities are active within this field, and process-engineering-oriented reviews and a specialized book are available. Microstructured systems can be applied with particular success in the investigation of highly exothermic and fast reactions. Often the presence of temperature-induced side reactions can be significantly reduced through isothermal operations. Although microstructured reaction techniques have been shown to optimize many synthetic procedures, they have not yet received the attention they deserve in organic chemistry. For this reason, this Review aims to address this by providing an overview of the chemistry in microstructured reactors, grouped into liquid-phase, gas-phase, and gas-liquid reactions.     

Silicon polypodands: powerful metal cation complexing agents and solid-liquid phase-transfer catalysts of new generation

Silicon polypodands 5-7 are found to be powerful complexing agents of alkali metal salts in low polarity solvents and very efficient catalysts in anion-promoted reactions under solid-liquid PTC conditions. The catalytic activity is comparable with that of the cyclic polyether PHDB18C6 8.     

Gas-phase activation and reaction dynamics of chiral ion-dipole complexes

A family of enantiomerically pure oxonium ions, that is O-protonated 1-aryl-1-methoxyethanes, has been generated in the gas phase by the (CH(3))(2)Cl(+) methylation of the corresponding 1-arylethanols. Some information on their reaction dynamics was obtained from a detailed kinetic study of their inversion of configuration and dissociation. The activation parameters of the inversion reaction are found to obey two different isokinetic relationships depending upon the nature and the position of the substituents in the oxonium ions. In contrast, the activation parameters of the dissociation reaction obey a single isokinetic relationship. The inversion and dissociation rate constants do not follow simple linear free-energy relationships. This complicated kinetic picture has been rationalized in terms of different activation dynamics in gaseous CH(3)Cl, which, in turn, determine the reaction dynamics of the oxonium ion. When the predominant activation of the oxonium ion involves resonant energy exchange from the 1015 cm(-1) CH(3) rocking mode of unperturbed CH(3)Cl, the inversion reaction proceeds through the dynamically most favored TS, characterized by the unassisted C(alpha)bond;O bond elongation. When, instead, the activation of the oxonium ions requires the formation of an intimate encounter complex with CH(3)Cl, the inversion reaction takes place via the energetically most favored TS, characterized by multiple coordination of the CH(3)OH moiety with the H(alpha) and H(ortho) atoms of the benzylic residue. The activation dynamics operating in the intimate encounter complex with CH(3)Cl is also responsible for the dissociation of most selected oxonium ions.     

Sequential reaction of p-toluidine with 2,3-dichloromaleic anhydride: Synthesis and molecular structure of 2-chloro-3-p-toluidino-N-p-tolylmaleimide

The reaction of equimolar amounts of p-toluidine with 2,3-dichloromaleic anhydride in refluxing toluene affords 2,3-dichloro-N-p-tolylmaleimide (1) and 2-chloro-3-p-toluidino-N-p-tolylmaleimide (2), as the major and minor products, respectively. While increasing the amount of p-toluidine relative to 2,3-dichloromaleic anhydride yields the latter compound as the major product, the replacement of the chloro group in 2-chloro-3-p-toluidino-N-p-tolylmaleimide by added p-toluidine was not observed in refluxing toluene. Both 1 and 2 were isolated by column chromatography and characterized in solution by IR and NMR spectroscopies. The solid-state structure of 2-chloro-3-p-toluidino-N-p-tolylmaleimide was solved by X-ray crystallography. Further, 2-Chloro-3-p-toluidino-N-p-tolylmaleimide crystallizes in the monoclinic space group C2/c, a = 33.191(8) Å, b = 4.037(1) Å, c = 24.876(6) Å, = 107.050(4)°, V = 3187(1) ų, Z = 8, and d _calc = 1.362 mg/m³; R = 0.0561, R _w = 0.1246 for 2087 reflections with I > 2 (I).