The relative rates of bromination of cyclohexane and cyclopentane with molecular bromine. Comparison of the reactions in solution and in vapor phase

1981 ◽  
Vol 59 (9) ◽  
pp. 1368-1374 ◽  
Author(s):  
Dennis D. Tanner ◽  
Tomoki C-S. Ruo ◽  
Hideki Takiguchi ◽  
Andre Guillaume
Keyword(s):  
Vapor Phase ◽  
Hydrogen Bromide ◽  
Bromine Atom ◽  
Relative Rate ◽  
Solution Phase ◽  
Molecular Bromine ◽  
Transfer Rates ◽  
Relative Rate Constants ◽  
Halogenated Alkanes ◽  
Relative Transfer

The relative rates of transfer of the cyclopentyl radical with molecular bromine and hydrogen bromide (k2′/k−1′) and with hydrogen tribromide and hydrogen bromide (k3′/k−1′) have been determined. The relative transfer rates are compared with the analogous values previously reported for the reactions of cyclohexyl radicals (k2/k−1 and k3/k−1). Utilizing the values of k2′/k−1 and k2/k−1 the competitive vapor phase rates of bromine atom abstraction of hydrogen from the two substrates could be obtained. An expression using a combination of the five sets of relative rate constants was used to determine the effect of competitive cage reversal which occurs in the solution phase bromination of the two substrate radicals with caged hydrogen bromide. For two structurally similar radicals, cage reversal (internal return) was found to affect the relative rates of bromination by 30%, while the relative transfer rates, although differing each by a factor of two, fortuitously nearly cancel each other's effect.The effect of both internal and external reversal reactions on the relative rates of bromination of structurally dissimilar substrates, halogenated alkanes and their parent hydrocarbons, is discussed.

ELECTROPHILIC CHARACTER OF OXYGEN ATOMS

1960 ◽  
Vol 38 (10) ◽  
pp. 1678-1687 ◽  
Author(s):  
R. J. Cvetanović
Keyword(s):  
Vapor Phase ◽  
Rate Constants ◽  
Relative Rate ◽  
Potential Significance ◽  
Relative Rate Constants ◽  
Electrophilic Character ◽  
Oxygen Atoms

The relative rates of reactions of oxygen atoms with a number of olefins in the vapor phase determined in previous work are summarized and supplemented by some additional results. The uncertainty in the values of the relative rate constants is now believed to be reduced to only a few per cent. A number of simple correlations observed previously have been re-examined on the basis of the more complete and more accurate list of values available at present. These correlations show a distinct electrophilic character of oxygen atoms in their reactions with olefins and their potential significance for the understanding of the finer details of these addition processes is discussed.

A reinvestigation of the vapor phase bromination of 2-bromobutane

1984 ◽  
Vol 62 (11) ◽  
pp. 2310-2316 ◽  
Author(s):  
Dennis D. Tanner ◽  
Tomoki C. S. Ruo ◽  
Yoshio Kosugi ◽  
Alan Potter
Keyword(s):  
Vapor Phase ◽  
Thermal Instability ◽  
Addition Reaction ◽  
Bromine Atom ◽  
Solution Phase ◽  
Reaction Schemes

The solution phase photobromination of 2-bromobutane yields 2,2-dibromobutane, meso-2,3-dibromobutane, dl-2,3-dibromobutane, small amounts of 1,2-dibromobutane, and 2,2,3-tribromobutane. However, in the corresponding vapor phase bromination these products appear along with other polybrominated products. The yield of these polybromides increases with temperature. The increase in yield of the polyhalogenated materials is rationalized by considering the thermal instability of the β-bromoalkyl radical, which eliminates a bromine atom to form the corresponding alkene. It is demonstrated that in the vapor phase allylic bromination competes successfully with bromine addition. Reaction schemes are suggested to explain the formation of polybromides. An explanation is also offered for the discrepancy between these results and those of previously reported vapor phase work.

Kinetics of the successive chlorination of 1,2-dichloroethane in the liquid phase

1969 ◽  
Vol 22 (6) ◽  
pp. 1177 ◽  
Author(s):  
DS Caines ◽  
RB Paton ◽  
DA Williams ◽  
PR Wilkinson
Keyword(s):  
Liquid Phase ◽  
Rate Constants ◽  
Relative Rate ◽  
Stirred Tank ◽  
Continuous Stirred Tank Reactor ◽  
Alternative Pathways ◽  
Tank Reactor ◽  
Relative Rate Constants ◽  
Continuous Stirred Tank ◽  
Kinetics Of

Liquid 1,2-dichloroethane has been chlorinated by dissolved chlorine to a succession of chloroethanes up to the ultimate hexachloroethane. The results of both batch and continuous stirred tank reactor systems have been analysed by computer techniques to give a set of relative rate constants from which one can predict the product composition for a given chlorine uptake, the aim in this work being to optimize the production of tetrachloroethanes. An unusual feature of the kinetics is that 1,1,1,2- and 1,1,2,2-tetrachloroethanes provide alternative pathways between 1,1,2-trichloroethane and pentachloroethane.

scholarly journals Kinetic study of the photochemical changes of (ZZ)-bilirubin IX α bound to human serum albumin. Demonstration of (EZ)-bilirubin IX α as an intermediate in photochemical changes from (ZZ)-bilirubin IX α to (EZ)-cyclobilirubin IX α

1985 ◽  
Vol 226 (1) ◽  
pp. 251-258 ◽  
Author(s):  
S Itoh ◽  
S Onishi
Keyword(s):  
Human Serum Albumin ◽  
Serum Albumin ◽  
Kinetic Study ◽  
Human Serum ◽  
Photochemical Reaction ◽  
Relative Rate ◽  
Significant Preference ◽  
Geometrical Isomers ◽  
Relative Rate Constants

The present study was performed to elucidate why the photochemical reaction of (ZZ)-bilirubin bound to human serum albumin is singularly selective, and only one of the two (EZ)- and (ZE)-bilirubins, the (ZE)-isomer, is produced. In a kinetic study of the photochemical reaction in vitro, the sum of the relative rate constants of photochemical transformation of (EZ)-bilirubin into both (EZ)-cyclobilirubin and (ZZ)-bilirubin, with a significant preference for the former, was proved to be considerably larger than that of the transformation of (ZZ)-bilirubin into (EZ)-bilirubin. Therefore only one of the geometrical isomers, namely (ZE)-bilirubin, is apparently formed. It was concluded that (EZ)-bilirubin photochemically undergoes (EZ)-cyclization, i.e. structural photoisomerization, while bound to its high-affinity site on human serum albumin, and is an intermediate in the transformation of (ZZ)-bilirubin into (EZ)-cyclobilirubin.

RECOMBINATION OF OPPOSITELY CHARGED AQUEOUS CLUSTER IONS USING ELECTROSTATICALLY MERGED ION BEAMS

1996 ◽  
Vol 03 (01) ◽  
pp. 655-660 ◽  
Author(s):  
B. PLASTRIDGE ◽  
K.A. COWEN ◽  
D.A. WOOD ◽  
M.H. COHEN ◽  
J.V. COE
Keyword(s):  
Rate Constants ◽  
Cluster Size ◽  
Collision Energy ◽  
Relative Rate ◽  
Center Of Mass ◽  
Cluster Ions ◽  
Charged Cluster ◽  
Relative Rate Constants ◽  
Oppositely Charged ◽  
Electrostatic Quadrupole

A new method for studying cluster-cluster interactions is introduced which involves merging mass-selected beams of oppositely charged cluster ions with an electrostatic quadrupole deflector. Recombination is monitored by measuring the rate of fast neutral production. Relative rate constants have been measured for the reaction of H 3O+( H 2 O )n+ OH −( H 2 O )m as a function of cluster size (m=n=0–3), which display a pronounced enhancement with clustering. Relative rate constants have also been measured as a function of center-of-mass collision energy for a heavily clustered reaction (n=3, m=3) and a lightly clustered reaction (n=1, m=0) revealing that clustering produces a dramatic change in the reaction mechanism.

REACTION OF OXYGEN ATOMS WITH BUTADIENE

1960 ◽  
Vol 38 (11) ◽  
pp. 2187-2195 ◽  
Author(s):  
R. J. Cvetanović ◽  
L. C. Doyle
Keyword(s):  
Pressure Dependence ◽  
Rate Constants ◽  
Room Temperature ◽  
Relative Rate ◽  
Excess Energy ◽  
General Mechanism ◽  
Arrhenius Parameters ◽  
Heats Of Reaction ◽  
Relative Rate Constants ◽  
Oxygen Atoms

Reaction of oxygen atoms with 1,3-butadiene has been investigated at room temperature. It is found that it conforms to the general mechanism established previously for the analogous reactions of monoolefins. Only 1,2-addition occurs, and the addition products, butadiene monoxide and 3-butenal, possess excess energy when formed as a result of high heats of reaction. The pressure dependence of the formation of the addition products yields the values of the "lifetimes" of the initially produced "hot" molecules. The relative rate constants have been determined at 25 and 127 °C and from these the relative values of the Arrhenius parameters have been calculated.

Untersuchung konkurrierender Reaktionen in strömenden Kohlenwasserstoff-Gemischen / Investigation of Competing Reactions in Flowing Mixtures of Hydrocarbons

1974 ◽  
Vol 29 (4) ◽  
pp. 642-649 ◽  
Author(s):  
R. Laupert ◽  
G. von Bünau
Keyword(s):  
Rate Constants ◽  
Atomic Hydrogen ◽  
Relative Rate ◽  
Experimental Conditions ◽  
Kinetic Evaluation ◽  
Alkyl Radicals ◽  
Relative Rate Constants ◽  
Flow Apparatus ◽  
Competing Reactions

The reactions of atomic hydrogen with propene, butene-2, and trimethylethylene, and with mixtures of these olefins with ethylene have been studied using flow apparatus. It was found that under the experimental conditions intermediate alkyl radicals reacted practically only with atomic hydrogen. This made possible a kinetic evaluation of the results yielding numerical values of several relative rate constants of competing intermediate reactions.

Sign in / Sign up

Export Citation Format

Share Document