The reactions of O(3P) with the butanols

1983 ◽  
Vol 61 (12) ◽  
pp. 2716-2720 ◽  
Author(s):  
John M. Roscoe
Keyword(s):  
Free Energy ◽  
Gas Phase ◽  
Rate Constants ◽  
Substrate Concentration ◽  
Kinetic Data ◽  
Absolute Rate ◽  
Gas Phase Reactions ◽  
Linear Free Energy ◽  
Different Types ◽  
Energy Relations

The reactions of O(3P) with the butanols were studied kinetically as a function of temperature and substrate concentration. The absolute rate constants for the gas phase reactions, in the units M−1 s−1, obey the following relations.[Formula: see text]The results suggest that although the α-CH bond in these alcohols is the most reactive one, reaction of O(3P) with other CH bonds in the alcohols is also appreciable. The kinetic data for these and other alcohols are separated into contributions from the different types of CH bonds and the results are discussed in terms of linear free energy relations.

The reactions of O(3P) with 2-propanone, 2-butanone, and 3-pentanone

1986 ◽  
Vol 64 (7) ◽  
pp. 1408-1414 ◽  
Author(s):  
John M. Roscoe
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Substrate Concentration ◽  
Activation Energies ◽  
Absolute Rate ◽  
The Absolute

The reactions of O(3P) with 2-propanone, 2-butanone, and 3-pentanone have been studied kinetically as a function of temperature and substrate concentration. The absolute rate constants for these reactions in the gas phase, in the units M−1 s−1, obey the following relations.[Formula: see text]The activation energies for these reactions are comparable to those for the reactions of O(3P) with alcohols, but the preexponential factors for the reactions of O(3P) with these ketones are significantly smaller than those for the analogous reactions with alcohols. The available data indicate that the reactivity of O(3P) toward ketones shows a variation with polar effects of substituents which is similar to that found for the reactions of OH with ketones.

Absolute rate constants for the gas-phase reactions of silylene with silane, disilane and the methylsilanes

1990 ◽  
Vol 86 (1) ◽  
pp. 27 ◽  
Author(s):  
James E. Baggott ◽  
H. Monty Frey ◽  
Phillip D. Lightfoot ◽  
Robin Walsh ◽  
Ivy M. Watts
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Absolute Rate ◽  
Gas Phase Reactions

Rate constants for decarboxylation reactions calculated using no barrier theory

2010 ◽  
Vol 88 (2) ◽  
pp. 79-98 ◽  
Author(s):  
J. Peter Guthrie ◽  
Sriyawathie Peiris ◽  
Margaret Simkin ◽  
Yun Wang
Keyword(s):  
Free Energy ◽  
Rate Constant ◽  
Rate Constants ◽  
Proton Exchange ◽  
Linear Free Energy ◽  
Free Energy Of Activation ◽  
Carbon Acids ◽  
Decarboxylation Rate ◽  
Energy Relations ◽  
Exchange Data

No barrier theory (NBT) provides both a qualitative way of thinking about what makes a reaction fast or slow and a quantitative way of calculating the rate constant (free energy of activation) corresponding to a particular mechanism. The origin and development of this idea are reviewed and examples of its use for qualitative understanding are presented before applying it to a set of decarboxylations. From the literature, a set of best values for rate constants for decarboxylation was picked. Detailed mechanistic models were developed for reactions leading to delocalized “anions” or to localized anions. It was necessary to have pKa values for ionizaion of the carbon acids corresponding to all of these species and these were selected from the literature or estimated by linear free energy relations (or occasionally calculated from proton exchange data). Over the entire range of measured decarboxylation rate constants, a range of 1025 in rate constant, the calculated values were in good agreement with experiment, with two exceptions: malonate dianion, which has been reported but probably not measured, and glycine, where it is possible that a different mechanism is being followed, unfortunately, one which we do not yet know how to treat by NBT. NBT is both a qualitatively and quantitatively useful tool for understanding chemistry.

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