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.

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 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.

Sign in / Sign up

Export Citation Format

Share Document