Reactions of thermal energy ions. VI. Hydrogen-transfer ion–molecule reactions involving polar molecules

1967 ◽  
Vol 45 (24) ◽  
pp. 3107-3117 ◽  
Author(s):  
S. K. Gupta ◽  
E. G. Jones ◽  
A. G. Harrison ◽  
J. J. Myher
Keyword(s):  
Mass Spectrometer ◽  
Thermal Energy ◽  
Pressure Measurement ◽  
Rate Constants ◽  
Hydrogen Transfer ◽  
Collision Theory ◽  
Protonated Molecule ◽  
Ion Molecule Reactions ◽  
Dipole Interactions ◽  
Made In

The rate constants for formation of the protonated molecule by ion–molecule reactions in CH3OH, (CH3)2O, and CH4 have been studied both at thermal energies and at 3.4 eV ion exit energy with a new mass spectrometer described in the present work. The rate constants are found to be approximately a factor of two greater than previously measured and it is concluded that an error in pressure measurement was made in the earlier work. Revised rate constants are presented for a number of systems studied previously. The results are compared with predictions of the collision theory modified in this paper to include the effect of ion-dipole interactions.

REACTIONS OF THERMAL ENERGY IONS: II. RATES OF SOME HYDROGEN TRANSFER ION–MOLECULE REACTIONS

1966 ◽  
Vol 44 (12) ◽  
pp. 1351-1359 ◽  
Author(s):  
A. G. Harrison ◽  
A. Ivko ◽  
T. W. Shannon
Keyword(s):  
Field Strength ◽  
Rate Constant ◽  
Thermal Energy ◽  
Rate Constants ◽  
Hydrogen Transfer ◽  
Thermal Reaction ◽  
Dipole Model ◽  
Protonated Molecule ◽  
Ion Molecule Reactions ◽  
Induced Dipole

The rate constants for the ion–molecule reactions forming the protonated molecule in CH3CN, H2, CH4, and CH3OCH3, the equivalent reactions in the deuteriated species, and the reactions forming COD+ in CO–CD4 mixtures have been measured at thermal energies and at 10.5 V/cm repeller field strength. For H2, HD, D2 and the reactions in CO–CD4 mixtures the rate constant for the thermal reaction is approximately 0.3–0.5 that of the 10.5 V/cm rate constant. For all other cases the ratio of rate constants is approximately unity as predicted by the ion-induced dipole model. The absolute values of the rate constants in most cases are considerably lower than predicted by theory.

Ion–molecule reactions in the binary mixture of acetaldehyde and trioxane. II. Mechanism for the reaction of acetaldehyde molecular ion with trioxane

1978 ◽  
Vol 56 (4) ◽  
pp. 533-537 ◽  
Author(s):  
Minoru Kumakura ◽  
Kazuo Arakawa ◽  
Toshio Sugiura
Keyword(s):  
Binary Mixture ◽  
Mass Spectrometer ◽  
Rate Constants ◽  
Positive Charge ◽  
Time Of Flight ◽  
Intermediate Complex ◽  
Hydrogen Atoms ◽  
Flight Mass Spectrometer ◽  
Ion Molecule Reactions ◽  
Product Ions

The ionic reaction of CH3CHO+with trioxane in acetaldehyde–trioxane mixtures has been studied using a time-of-flight mass spectrometer. The product ions, C3H5O2+, C3H6O2+, and C3H7O2+, were formed by condensation–elimination reactions, which involve the elimination of aformaldehyde molecule. The dissociation of the intermediate-complex, CH3CHO(CH2O)3+*, leads to the formation of the product ions. The structure of the complex is linear with localized positive charge. Rearrangement of hydrogen atoms occurs in the complex but not extensive scrambling. From the distribution of the isotopic product ions in acetaldehyde-d4–trioxane mixtures it was proposed that the origins of the product ions are the acetaldehyde molecule (reactant ion) and fragments from trioxane. The rate constants for the product ions formed in acetaldehyde (or acetaldehyde-d4)–trioxane mixtures were obtained.

Ion–molecule reactions in formic-d acid and methyl formate

1968 ◽  
Vol 46 (12) ◽  
pp. 2141-2146 ◽  
Author(s):  
Howard Pritchard ◽  
J. C. J. Thynne ◽  
A. G. Harrison
Keyword(s):  
Rate Constants ◽  
Methyl Formate ◽  
Ion Molecule Reactions ◽  
Dipole Interactions ◽  
Induced Dipole ◽  
Energy Formula ◽  
Good Agreement

The following ion–molecules reactions have been found to occur in DCOOH for ions produced by bombardment with electrons of 10–15 eV energy (all rate constants in cm3 molecule−1 units).[Formula: see text]In methyl formate the following reactions have been identified and rate constants measured for ions formed by bombardment with electrons of 10–15 eV energy.[Formula: see text]Experiments using DCO2CH3 show that reaction [f] involves transfer of the methyl hydrogen at a rate 1.5 times that of the formyl hydrogen while reaction [g] involves transfer from only the methyl position of CH3OH+. The rate constants for all reactions are considerably higher than predicted on the basis of ion–induced dipole interactions only but are in good agreement with values calculated by including ion–dipole interactions.

Rate constants of thermal energy binary ion-molecule reactions of aeronomic interest

1973 ◽  
Vol 12 (2) ◽  
pp. 159-178 ◽  
Author(s):  
Eldon E. Ferguson
Keyword(s):  
Thermal Energy ◽  
Rate Constants ◽  
Ion Molecule Reactions

Thermal Ion-Molecule Reactions in Oxygen-Containing Molecules. Condensation-Elimination Reactions in Dimethyl Ether-Trioxane Mixtures

1977 ◽  
Vol 32 (12) ◽  
pp. 1533-1540 ◽  
Author(s):  
Minoru Kumakura ◽  
Toshio Sugiura
Keyword(s):  
Isotope Effect ◽  
Dimethyl Ether ◽  
Mass Spectrometer ◽  
Rate Constants ◽  
Linear Structure ◽  
Ionization Efficiency ◽  
Ion Molecule Reactions ◽  
Fragment Ions ◽  
Product Ions ◽  
Elimination Reactions

Abstract Thermal ion-molecule reactions in dimethyl ether - trioxane mixtures have been studied with a time-of-flight mass spectrometer. The appearance potentials and ionization efficiency curves of product and major fragment ions were measured by an RPD technique. The product ions, having a linear structure such as CH3OCH3(CH2O)n+, CH3OCH3(CH2O)nH+, CH3OCH2(CH2O)n+, and CH3OCH2(CH2O)nH+ (n = 1 - 3), are formed by condensation-elimination reactions of CH3OCH3+ and CH3OCH2+ with trioxane. The formation of the product ions involves the dissociation of an intermediate-complex, which has a linear structure. It was found that homo-elimination of neutral products occurs preferentially from the trioxane molecule site in the complex. Extensive scrambling does not take place. The rate constants for the ions formed in dimethyl ether (or dimethyl-d6 ether) - trioxane mixtures are obtained, and a small isotope effect is observed. The rate constants of the condensation-elimination reactions of CH3OCH2+ with trioxane are compared with those with dimethyl ether.

ION–MOLECULE REACTIONS IN METHYL ALCOHOL AND METHYL-d3 ALCOHOL

1966 ◽  
Vol 44 (14) ◽  
pp. 1655-1661 ◽  
Author(s):  
J. C. J. Thynne ◽  
F. K. Amenu-Kpodo ◽  
A. G. Harrison
Keyword(s):  
Methyl Alcohol ◽  
Rate Constants ◽  
Hydrogen Transfer ◽  
Rate Coefficients ◽  
Collision Complex ◽  
Ion Molecule Reactions ◽  
Ion Energies ◽  
Hydroxyl Hydrogen

The rate constants for the hydrogen-transfer ion-molecule reactions[Formula: see text]have been measured at thermal ion energies and found to be 12 × 10−10 cm3 molecule−1 s−1 and 8.0 × 10−10 cm3 molecule−1 s−1 respectively. The rate coefficients at higher ion energies (3.7 eV ion exit energy) show little change from these values. Reactions [a] and [b] have also been studied using CD3OH and it is found that in reaction [a] the hydroxyl hydrogen is transferred 2.5 times more readily at low ion energies and 1.8 times more readily at high ion energies than a methyl hydrogen. This rather small specificity would appear to preclude formation of a "locked-in" collision complex even at low ion energies.

Calculations of rate constants for ion—molecule reactions in a pulsed-source mass spectrometer

1969 ◽  
Vol 2 (4-5) ◽  
pp. 385-390 ◽  
Author(s):  
Bryan G. Reuben ◽  
Assa Lifshitz ◽  
Chava Lifshitz
Keyword(s):  
Mass Spectrometer ◽  
Rate Constants ◽  
Source Mass ◽  
Ion Molecule Reactions

Ion–molecule reactions in carbonyl sulfide – hydrocarbon mixtures

1970 ◽  
Vol 48 (4) ◽  
pp. 664-673 ◽  
Author(s):  
I. Džidić ◽  
A. Good ◽  
P. Kebarle
Keyword(s):  
Mass Spectrometer ◽  
Cross Sections ◽  
Rate Constants ◽  
Carbonyl Sulfide ◽  
Independent Set ◽  
Graphical Analysis ◽  
Ion Molecule Reactions ◽  
Product Ions ◽  
The Individual ◽  
Approximate Rate

The major ion–molecule reactions occurring in pure COS and in mixtures of COS with methane, methyl iodide, ethane, and ethylene were investigated in a Nier-type mass spectrometer. In cases where two or more reactions could be postulated to account for the observed product ions, appearance potential data and graphical analysis were used to evaluate the contributions of the individual reactions. Phenomenological cross sections were obtained for the reactions studied and approximate rate constants were then calculated.An independent set of measurements were carried out in a high-pressure pulsed-beam mass spectrometer, in which the absolute rate constants for reactions occurring in COS were measured, using nitrogen as a carrier gas. The rate constants thus obtained were used to verify the validity of the rate constants calculated from the measured cross sections.

PLATELET AGGREGATION DOES NOT CONFORM TO SIMPLE PARTICLE COLLISION THEORY

1987 ◽  
Author(s):  
Moideen P Jamaluddin
Keyword(s):  
Platelet Aggregation ◽  
Rate Equation ◽  
Rate Constants ◽  
Kinetic Scheme ◽  
Order Type ◽  
Second Order ◽  
Particle Collision ◽  
Collision Theory ◽  
Rate Law ◽  
First Order

Platelet aggregation kinetics, according to the particle collision theory, generally assumed to apply, ought to conform to a second order type of rate law. But published data on the time-course of ADP-induced single platelet recruitment into aggregates were found not to do so and to lead to abnormal second order rate constants much larger than even their theoretical upper bounds. The data were, instead, found to fit a first order type of rate law rather well with rate constants in the range of 0.04 - 0.27 s-1. These results were confirmed in our laboratory employing gelfiltered calf platelets. Thus a mechanism much more complex than hithertofore recognized, is operative. The following kinetic scheme was formulated on the basis of information gleaned from the literature.where P is the nonaggregable, discoid platelet, A the agonist, P* an aggregable platelet form with membranous protrusions, and P** another aggregable platelet form with pseudopods. Taking into account the relative magnitudes of the k*s and assuming aggregation to be driven by hydrophobic interaction between complementary surfaces of P* and P** species, a rate equation was derived for aggregation. The kinetic scheme and the rate equation could account for the apparent first order rate law and other empirical observations in the literature.

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