17032-11-0Relevant articles and documents
Photoionization-Induced Intracluster Reactions of Chlorobenzene/Ammonia Mixed Complexes
Grover, J. R.,Cheng, B.-M.,Herron, W. J.,Coolbaugh, M. T.,Peifer, W. R.,Garvey, J. F.
, p. 7479 - 7487 (1994)
Complexes of chlorobenzene and ammonia, C6H5Cl*NH3, C6H5Cl(NH3)2, and C6H5Cl(NH3)3, were studied by single-photon ionization.The ionization potentials of these three complexes were measured to be 8.744 +/- 0.022, 8.652 +/- 0.013, and 8.555 +/- 0.012 eV, respectively.The appearance potential of C6H5NH3+ from C6H5Cl*NH3 was found at 8.935 +/- 0.004 eV, which, with the known heat of formation of anilinium ion, gives the dissociation energy D(C6H5Cl*NH3) = 2.9 +/- 0.5 kcal mol-1 (12.0 +/- 2.2 kJ mol-1).Then, from its onset energy from C6H5Cl*NH3, the dissociation energy of (C6H5Cl*NH3)+ is calculated to be D+> = 10.4 +/- 0.7 kcal mol-1 (43.5 +/- 2.9 kJ mol-1), unusually large for a heterodimer ion.No production of C6H5NH3+ from trimers could be detected in the onset region.The ion C6H5NH2+ has onsets of 8.849 +/- 0.009 and 8.855 +/- 0.029 eV from C6H5Cl*NH3 and C6H5Cl(NH3)2, respectively.These energies are below the onset for C6H5NH3+ but far above the thermochemical thresholds for aniline ion, which are near 7.6 eV.Evidently, C6H5NH2+ is not produced by dissociative ionization of the excited neutral complex.Instead, the complex must first be ionized and excited to at least 0.1 eV.Since the onsets for (C6H5Cl*NH3)+ and C6H5NH2+ are lower that for C6H5NH3+, then (C6H5Cl*NH3)+ in its ground state does not spontaneously form C6H5NH3+.Kinetic energy release distributions measured for C6H5NH2+ and C6H5NH3+ indicate that the formation of both ions is consistent with statistical process; i.e., no evidence for nonstatistical mechanisms was found, even for photon energies as large as 17.7 eV.
Calorimetric Determination of Thermodynamic Parameters for the Dissociations of Acids in Dipolar Aprotic Solvents
Izutsu, Kosuke,Nakamura, Toshio,Takizawa, Katsumi,Takeda, Akihiko
, p. 455 - 458 (1985)
A calorimetric method has been investigated for the determination of the thermodynamic parameters of acid dissociations in dipolar aprotic solvents.For the dissociations of monoprotonated bases BH+ (B: aniline, pyridine, triethylamine, tributyl
Nucleophilic Substitution within the Photoionized van der Waals Complex C6H5Cl-NH3
Maeyama, Toshihiko,Mikami, Naohiko
, p. 6973 - 6977 (1990)
Efficient generation of C6H5NH3+ was found after the selective ionization of the van der Waals complex C6H5Cl-NH3 which was prepared in a supersonic molecular beam.The action spectrum of the product and its appearance energy were observed by using the two-color mass-selected multiphoton ionization spectroscopy.From the energetics of the reaction it was concluded that the ion-molecule reaction is responsible for the process and the product is generated by the nucleophilic substitution reaction occurring within the photoionized van der Waals complex.
IR absorption spectra of aniline cation, anilino radical, and phenylnitrene isolated in solid argon
Chou, Sheng-Lung,Lin, Shu-Yu,Tseng, Chien-Ming,Wu, Yu-Jong
, (2022/04/12)
Electron bombardment of aniline (PhNH2) in an Ar matrix mainly generated the aniline cation (PhNH2+), anilino (PhNH) and phenyl (Ph) radicals, and phenylnitrene (PhN). Further irradiation of the electron-bombarded matrix s
Charged states of proteins. Reactions of doubly protonated alkyldiamines with NH3: Solvation or deprotonation. Extension of two proton cases to multiply protonated globular proteins observed in the gas phase
Peschke, Michael,Blades, Arthur,Kebarle, Paul
, p. 11519 - 11530 (2007/10/03)
The apparent gas-phase basicities (GBapp'S) of basic sites in multiply protonated molecules, such as proteins, can be approximately predicted. An approach used by Williams and co-workers was to develop an equation for a diprotonated system, NH
Benzene as a Selective Chemical Ionization Reagent Gas
Allgood, Charles,Lin, Yi,Ma, Yee-Chung,Munson, Burnaby
, p. 497 - 502 (2007/10/02)
Dilute mixtures of C6H6 or C6D6 in He provide abundant +. or +. ions and small amounts of + or + ions as chemical ionization (CI) reagent ions.The C6H6 or C6D6 CI spectra of alkylbenzenes and alkylanilines contain predominantly M+. ions from reactions of +. or +. and small amounts of MH+ or MD+ ions from reactions of + or +.Benzene CI spectra of aliphatic amines contain M+., fragment ions and sample-size dependent MH+ ions from sample ion-sample molecules reactions.The C6D6 CI spectra of substituted pyridines contain M+. and MD+ ions in different ratios depending on the substituent (which alters the ionization energy of the substituted pyridine), as well as sample-size-dependent MH+ ions from sample ion-sample molecule reactions.Two mechanisms are observed for the formation of MD+ ions: proton transfer from +. or charge transfer from +. to give M+., followed by deuteron transfer from C6D6 to M+..The mechanisms of reactions were established by ion cyclotron resonance (ICR) experiments.Proton transfer from +. or +. is rapid only for compounds for which proton transfer is exothermic and charge transfer is endothermic.For compounds for which both charge transfer and proton transfer are exothermic, charge transfer is the almost exclusive reaction.
A systematic entropy relationship for the general-base catalysis of the deprotonation of a carbon acid. A quantitative probe of transition-state solvation
Bunting, John W.,Stefanidis, Dimitrios
, p. 779 - 786 (2007/10/02)
The general-base-catalyzed deprotonation of a carbon acid, the l-methyl-4-(phenylacetyl)pyridinium cation (pKa = 9.02 at 25 °C), has been investigated for 32 general-base catalysts (25 amines and seven phenoxide ions) in aqueous solution. Amines give a generally scattered Bronsted plot; ring-substituted benzylamines have ?= 0.52, and ring-substituted phenoxides have ?= 0.60, with the phenoxides being more reactive than amines of similar basicity. The temperature dependences of the general-base-catalyzed deprotonation of this carbon acid have been measured over the range 15-45 °C for 12 base catalysts (eight primary, secondary, and tertiary amines; 4-(dimethylamino)pyridine; two phenoxide ions; hydroxide ion). The entropies of activation for these deprotonations show a clean curvilinear dependence upon the entropies of protonation of these base species, with the hydroxide ion being the only significant deviant from this relationship. This observation quantitatively establishes the importance of solvation effects as the major source of deviations that are commonly observed in Bronsted relationships for general-base-catalyzed processes.
Investigation of Reaction Barriers in Mixed Organic Aggregates by Two-Color Resonant Two Photon Ionization
Awdiew, J.,Riehn, Ch.,Brutschy, B.,Baumgaertel, H.
, p. 1353 - 1357 (2007/10/02)
We used two-color resonant two-photon ionization combined with time-of-flight mass spectrometry to study nucleophilic ipso-substitution reactions with halobenzenes radical cations.Molecular clusters serve as microscopic test tubes to tackle the reactivity problem of solvated radical cations.The reaction paths - van der Waals fragmentation and chemical reaction - could be energetically separated.The substitution reactions turned out to be nearly activationless.The particularities of the excitation process are discussed.
Electrostatic Catalysis by Ionic Aggregates. 6. Modulation of Proton-Transfer Equilibria by Lithium Perchlorate-Diethyl Ether Clusters
Pocker, Y.,Ciula, James C.
, p. 2904 - 2909 (2007/10/02)
This study shows that the proton-transfer reaction of tropolone (2-hydroxy-2,4,6,-cycloheptatrien-1-one) with amine bases in diethyl ether is subject to substantial changes in the apparent equilibrium constant with changes in the concentration of lithium
Thermochemistry of Silaethylene and Methylsilylene from Experiment and Theory
Shin, Seung Koo,Irikura, Karl K.,Beauchamp, J. L.,Goddard, William A.
, p. 24 - 30 (2007/10/02)
Fourier transform ion cyclotron resonance spectroscopy has been used to examine the deprotonation energetics of the methylsilyl cation, CH3SiD2+, to yield silaethylene and methylsilylene proton affinities of 205 +/- 3 and 215 +/- 4 kcal/mol, respectively.These values combined with the known heat of formation of methylsilyl cation, yield ΔHof 298(CH2SiH2) = 43 +/- 3 kcal/mol and ΔHof 298(CH3SiH) = 53 +/- 4 kcal/mol.These results are corroborated by ab initio generalized valence bond-configuration interaction calculations which indicate that silaethylene is more stable than methylsilylene by 11.6 kcal/mol, in excellent agreement with the experimental difference (10 +/- 3 kcal/mol).The adiabatic ionization potential of methylsilylene is calculated to be 8.22 eV, which is lower than the value of 8.85 eV determined for silaethyene using photoelectron spectroscopy.
