29131-39-3Relevant academic research and scientific papers
Ionic substitution reaction in small dihalogenated benzene-(NH3)n clusters studied through threshold photoeleectron-photoion coincidences
Dedonder-Lardeux, C.,Dimicoli, I.,Jouvet, C.,Martrenchard-Barra,S.,Richard-Viard, M.,et al.
, p. 97 - 104 (2007/10/02)
Substitution reactions in small ionic fluorochlorobenzene-(NH3)n clusters have been studied through threshold photoelectron-photoion coincidence techniques using synchrotron radiation.In this experiment the internal energy of the cluster ion is well defined and therefore the change of the reactive pathways with the internal energy content of the parent ion can be evidenced.
Chemical Reactivity in Microscopic Systems: The Nucleophilic Substitution of Halogenated Benzene Ions by Ammonia Studied in Molecular Clusters
Martrenchard-Barra, S.,Dedonder-Lardeux, C.,Jouvet, C.,Rockland, U.,Solgadi, D.
, p. 13716 - 13730 (2007/10/02)
The reactivity of small dihalogenated benzene ions clustered with ammonia has been investigated through mass-selected two-color two-photon ionization.Two reaction channels are evidenced: halogen elimination and hydrogen halide elimination.Appearance thresholds of the different reactive paths have been measured as well as the kinetics of the reactions.From these measurements, a new reactive scheme is proposed.
Chemical Reactions in Mixed Molecular Clusters, Studied by Resonant Two-Photon Ionization
Brutschy, Bernhard
, p. 1154 - 1160 (2007/10/02)
After a short overview on the different types of intracluster reactions, observed so far, this survey focuses on nucleophilic ipso-substitution (SN) reactions in clusters consisting of one (1,n)-chlorofluorobenzene cation with one (1:1) of two (1:2) ammonia molecules.The reaction efficiencies are compared with that in bimolecular ion-molecule reactions as studied by Thoelmann and Gruetzmacher.Two types of (SN2)-reactions are observed, 1. abstraction of a chlorine radical, 2. abstraction of HX (X=Cl,F).The latter reaction is only observed in clusters but not in an ion-molecule gas phase collision.For both channels different mechanisms are proposed.The Cl-production strongly depends on the dipole moment of the neutral chromophore.It is rationalized in the framework of the theory of Shaik and Pross on polar reactions by an electron transfer as rate determining step.The HX formation channel, on the other hand is explained by a transition state with a concerted electron and proton transfer.It is strongly promoted by additional solvent molecules, probably due to bifunctional catalysis. Keywords: Catalysis / Clusters / Mass Spectrometry / Multi-photon Processes
Reactions of dihalobenzene radical cations with ammonia in the gas phase. Reactivity pattern for nucleophilic aromatic substitution
Th?lmann, Detlef,Grützmacher, Hans-Friedrich
, p. 3281 - 3287 (2007/10/02)
The reactions of homo- and heterodisubstituted dihalobenzene radical cations with NH3 were investigated by FT-ICR spectrometry. A halogen atom X (X = Cl, Br, I) is substituted in a gas-phase nucleophilic ipso substitution, yielding haloanilinium ions. The reaction efficiency, i.e., the percentage of reactive ion-molecule collisions, ranges from 3 proceeds by a multistep reaction mechanism with a double-well potential energy surface. The rate-determining step is the addition of NH3 to the aromatic radical cation in the collision complex. The structural parameters influencing this reaction step can be analyzed by the reactivity model of polar reactions of Shaik and Pross. From this the most important feature of the substitution reaction of mono- and dihalobenzene radical cations with NH3 is the different charge localization in reactants and products. This results in a strong influence of the difference of the ionization energies of the halogenated benzene and NH3 and of the dipole moment of the halogenated benzene, i.e., the precursor of the ionic reactant, on the activation energy of the addition step.
