Alkylation of benzene by alkyl cations. Stability of the tert-butyl benzenium ion

1982 ◽  
Vol 60 (18) ◽  
pp. 2325-2331 ◽  
Author(s):  
D. K. Sen Sharma ◽  
S. Ikuta ◽  
P. Kebarle
Keyword(s):  
Gas Phase ◽  
Equilibrium Constants ◽  
Ion Source ◽  
Phase Reaction ◽  
Source Pressure ◽  
Pulsed Electron Beam ◽  
Gas Phase Reaction ◽  
Alkyl Cations ◽  
Alkylation Of Benzene ◽  
Energy Formula

The kinetics and equilibria of the gas phase reaction [1] tert-C4H9+ + C6H6 = tert-C4H9C6H6+ were studied with a high ion source pressure pulsed electron beam mass spectrometer. Equilibria [1] could be observed in the temperature range 285–325 K. van't Hoff plots of the equilibrium constants led to [Formula: see text] and [Formula: see text]. The rate constants at 305 K were klf = 1.5 × 10−28 molecules−2 cm6 s−1 and klr = 2.9 × 10−1 molecules−1 cm3 s−1. tert-C4H9C6H6+ dissociates easily via [lr] not only because of the low dissociation energy [Formula: see text] but also because of the unusually favorable entropy [Formula: see text]. The occurrence of transalkylation reactions: tert-C4H9C6H6+ + alkylbenzene = tert-C4H9 alkylbenzene+ + benzene, was discovered in the present work.

Stabilities of complexes (N2)nH+, and (O2)nH+ for n = 1 to 7 based on gas phase ion-equilibria measurements

1979 ◽  
Vol 57 (16) ◽  
pp. 2159-2166 ◽  
Author(s):  
K. Hiraoka ◽  
P. P. S. Saluja ◽  
P. Kebarle
Keyword(s):  
Electron Beam ◽  
Gas Phase ◽  
Equilibrium Constants ◽  
Ion Source ◽  
Large Decrease ◽  
Proton Affinities ◽  
Source Pressure ◽  
Pulsed Electron Beam ◽  
The Stability ◽  
Gas Phase Ion

The equilibria Bn−1H+ + B = BnH+ for B = N2, CO, and O2 were measured with a pulsed electron beam high ion source pressure mass spectrometer. Equilibria up to n = 7 could be observed. van't Hoff plots of the equilibrium constants lead to ΔGn−1,n0, ΔHn−1,n0, and ΔSn−1,n0. While the proton affinities increase in the order O2 < N2 < CO, the stabilities of the B2H+ towards dissociation to BH+ + B increase in the reverse order, i.e. CO < N2 < O2. The stabilities towards dissociation of B for BnH+ where n > 2 are much lower for all three compounds; however for N2 and CO the stability decreases only very slowly from n = 3 to n = 6, then there is a large fall off for n = 7. The (O2)nH+ clusters show large decrease of stabilities as n increases. The BnH+ (for n > 3) of CO are more stable than those of N2 or O2. The above experimental results can be partially explained with the help of results from molecular orbital STO-3G calculations for B, BH+, and B2H+ and general considerations. BH+ and B2H+ for CO and N2 are found to be linear while those for O2 are bent. The most stable O2H+ is a triplet, while (O2)2H+ is a quintuplet.

Formation of tert-butyl cation in methane

1976 ◽  
Vol 54 (11) ◽  
pp. 1739-1743 ◽  
Author(s):  
K. Hiraoka ◽  
P. Kebarle
Keyword(s):  
Temperature Dependence ◽  
Gas Phase ◽  
Arrhenius Plot ◽  
Ion Source ◽  
Probable Mechanism ◽  
Positive Temperature ◽  
Phase Reaction ◽  
Source Pressure ◽  
Gas Phase Reaction ◽  
Pure Methane

The reactions of CH3+ with pure methane in the torr range show an interesting temperature dependence. C2H5+ is formed at all temperatures by the well known reaction: CH3+ + CH4 = C2H5+ + H2. In the lowest temperature interval studied (105–125 K) C2H5+ adds two CH4 molecules to give a C4H13+ species. At higher temperatures only one CH4 molecule is added on. The resulting C3H9+ then reacts with one more CH4 molecule according to reaction 6.[Formula: see text]The rate constant k6 is found to be second order and has a positive temperature dependence. An Arrhenius plot gives:[Formula: see text]At temperatures above 200 K reaction 6 ceases to occur since C3H9+, being unstable at high temperatures, decomposes to s-C3H7+ + H2.The reactions were studied using ultra pure methane irradiated with electrons in a pulsed beam high ion source pressure mass spectrometer.The gas phase reaction mechanism for the formation of t-C4H9+ is found to bear close re-semblance to the probable mechanism by which the t-C4H9+ ion is formed from methane dissolved in superacid media.

Gas phase ion equilibria: heats of formation of acylium ions RCO+ and protonated acids RC(OH)2+; gas phase catalysis of proton shift RC(OH)2+ → RCO(OH2)+

1979 ◽  
Vol 57 (24) ◽  
pp. 3205-3215 ◽  
Author(s):  
W. R. Davidson ◽  
S. Meza-Höjer ◽  
P. Kebarle
Keyword(s):  
Gas Phase ◽  
Negative Temperature ◽  
Ion Source ◽  
Activation Energy Barrier ◽  
Third Order ◽  
Source Pressure ◽  
Pulsed Electron Beam ◽  
Proton Shift ◽  
Gas Phase Ion ◽  
Good Agreement

The equilibria [2]: [Formula: see text] for R = CH3, C2H5, and C6H5 were studied in a pulsed electron beam high ion source pressure mass spectrometer. van't Hoff plots led to ΔH2 values: (CH3), 24.6; (C2H5), 22.7; (C6H5), 21.9 kcal/mol. ΔHf(RC(OH)2+) were obtained from gas phase basicity ladders combined with the new ΔHf(t-butyl+) = 163 kcal/mol (Beauchamp). The ΔHf(RC(OH)2+) were: (CH3), 71.3; (C2H5), 63.6; (C6H5), 95.5 kcal/mol. Combination of ΔH2 with ΔHf(RC(OH)2+) leads to ΔHf(RCO+): (CH3), 153.7; (C2H5), 144; (C6H5), 174.6 kcal/mol. These results are in agreement with selected data from appearance potentials. The energies and structures of the participants in reaction [2] were calculated by MINDO/3 and STO-3G. MINDO/3 gave good agreement with ΔH2. The establishment of the equilibria [2] was unusually slow. A study of the kinetics revealed that k2f is approximately third order, unusually small, and has an unusually large negative temperature coefficient. Furthermore, reaction [2] was found to be catalyzed by RCOOH. An explanation of these observations is given by assuming that the proton shift RCO(OH2)+ → RC(OH)2+ has a large activation energy barrier in the gas phase. This barrier is removed by formation of a hydrogen bonded complex with RCOOH.

Prediction of Alkanolamine pKa Values by Combined Molecular Dynamics Free Energy Simulations and ab initio Calculations

2019 ◽  
Author(s):  
Javad Noroozi ◽  
William Smith
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
Ab Initio Calculations ◽  
Gas Phase ◽  
Quantum Chemical ◽  
Phase Reaction ◽  
Pka Values ◽  
Gas Phase Reaction ◽  
Reaction Free Energy ◽  
Energy Simulations

We use molecular dynamics free energy simulations in conjunction with quantum chemical calculations of gas phase reaction free energy to predict alkanolamines pka values. <br>

Metabolic alteration of Methylococcus capsulatus str. Bath during a microbial gas-phase reaction

2021 ◽  
Vol 330 ◽  
pp. 125002
Author(s):  
Yan-Yu Chen ◽  
Yuki Soma ◽  
Masahito Ishikawa ◽  
Masatomo Takahashi ◽  
Yoshihiro Izumi ◽  
...  
Keyword(s):  
Gas Phase ◽  
Phase Reaction ◽  
Methylococcus Capsulatus ◽  
Gas Phase Reaction ◽  
Metabolic Alteration

scholarly journals Influence of Water on the Gas-Phase Reaction of Dimethyl Sulfide with BrO in the Marine Boundary Layer

ACS Omega ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 2410-2419
Author(s):  
Junyao Li ◽  
Narcisse T. Tsona ◽  
Shanshan Tang ◽  
Xiuhui Zhang ◽  
Lin Du
Keyword(s):  
Boundary Layer ◽  
Gas Phase ◽  
Dimethyl Sulfide ◽  
Marine Boundary Layer ◽  
Phase Reaction ◽  
Gas Phase Reaction ◽  
Influence Of Water

Preparation of SiC hollow particles by gas-phase reaction in the SiH4-CH4-H2 system

1989 ◽  
Vol 24 (10) ◽  
pp. 3679-3685 ◽  
Author(s):  
C. H. Pai ◽  
K. Koumoto ◽  
S. Takeda ◽  
H. Yanagida
Keyword(s):  
Gas Phase ◽  
Phase Reaction ◽  
Hollow Particles ◽  
Gas Phase Reaction

scholarly journals Fabrication and Particle Size Control of Oxide Nanoparticles by Gas Phase Reaction Assisted with DC Plasma

2007 ◽  
Vol 44 (6) ◽  
pp. 447-452 ◽  
Author(s):  
Akira Watanabe ◽  
Motoharu Fujii ◽  
Masayoshi Kawahara ◽  
Takehisa Fukui ◽  
Kiyoshi Nogi
Keyword(s):  
Particle Size ◽  
Gas Phase ◽  
Size Control ◽  
Oxide Nanoparticles ◽  
Phase Reaction ◽  
Dc Plasma ◽  
Gas Phase Reaction ◽  
Particle Size Control

Formation of Carbamate Anions by the Gas-phase Reaction of Anilide Ions with CO2

2016 ◽  
Vol 27 (5) ◽  
pp. 927-939 ◽  
Author(s):  
Chongming Liu ◽  
Upul Nishshanka ◽  
Athula B. Attygalle
Keyword(s):  
Gas Phase ◽  
Phase Reaction ◽  
Gas Phase Reaction
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