Temperature dependence of rate constants for reaction of oxygen atoms, O(3P), with allene and 1,3-butadiene

1979 ◽  
Vol 57 (9) ◽  
pp. 949-952 ◽  
Author(s):  
W. S. Nip ◽  
D. L. Singleton ◽  
R. J. Cvetanović

Rate constants were determined for the reactions of O(3P) atoms with allene and with 1,3-butadiene by a phase shift technique in which oxygen atoms were generated by modulated mercury photosensitized decomposition of nitrous oxide and monitored by the chemiluminescence from their reaction with NO. Over the temperature interval 297–574 K, the Arrhenius equation for the O(3P) + allene reaction is k1A = (2.99 ± 0.41) × 10−11 exp [(−941 ± 54)/T] cm3 molecule−1 s−1, where the indicated uncertainties are 95% confidence limits. At 299 and 488 K, the rate constant for O(3P) + 1,3-butadiene is essentially the same, within 10%, with an average value of 2.07 × 10−11 cm3 molecule−1 s−1.


1978 ◽  
Vol 56 (23) ◽  
pp. 2934-2939 ◽  
Author(s):  
D. L. Singleton ◽  
R. J. Cvetanović

Rate constants for the reactions O(3P) + HX → OH + X (X = Br, I) have been determined by a phase shift technique. Oxygen atoms were generated by modulated mercury photosensitized decomposition of nitrous oxide, and were monitored by the chemiluminescence from the reaction with nitric oxide. Over the temperature interval 298–554 K, the rate constants are satisfactorily represented by the Arrhenius expressions kO+HBr = (8.09 ± 0.86) × 109 exp (−3.59 ± 0.08)/RT and kO+HI = (2.82 ± 0.27) × 1010 exp (−1.99 ± 0.07)/RT, where the units are ℓ mol−1 s−1 and kcal mol−1. The indicated uncertainties are one standard deviation. The results of bond energy–bond order calculations, incorporating recently proposed modifications, are discussed.



1975 ◽  
Vol 63 (2) ◽  
pp. 1003-1007 ◽  
Author(s):  
D. L. Singleton ◽  
S. Furuyama ◽  
R. J. Cvetanović ◽  
R. S. Irwin


1977 ◽  
Vol 55 (18) ◽  
pp. 3321-3327 ◽  
Author(s):  
D. L. Singleton ◽  
R. S. Irwin ◽  
R. J. Cvetanović

The phase-shift technique has been used to determine the temperature dependence of the reaction of ground state oxygen atoms with several aldehydes. Oxygen atoms were generated by modulated photosensitized decomposition of nitrous oxide and were monitored by the chemiluminescence from their reaction with nitric oxide. The Arrhenius expressions determined over the temperature interval 298–472 K are: k1 (acetaldehyde) = (7.21 ± 1.49) × 109 exp (−1960 ± 153/RT); k1(propionaldehyde) = (7.78 ± 0.75) × 109 exp (−1727 ± 66/RT); k1(butyralde-hyde) = (9.99 ± 0.56) × 109 exp (−1702 ± 40/RT); k1(isobutyraldehyde) = (7.92 ± 1.02) × 109 exp (−1445 ± 91/RT), where the units are ℓ mol−1 s−1 and cal mol−1. The indicated uncertainties are one standard deviation. After small corrections were made for the potential abstraction of alkyl hydrogens, the activation energies of aldehydic hydrogen abstraction were used to estimate the aldehydic C—H bond dissociation energies, D(RCO—H). The trend of slightly decreasing values of D(RCO—H) thus obtained for the sequence H2CO, CH3CHO, C2H5CHO, n-C3H7CHO, i-C3H7CHO was also indicated by the aldehydic C—H stretching frequencies.







2002 ◽  
Vol 67 (5) ◽  
pp. 347-351 ◽  
Author(s):  
Smiljana Markovic ◽  
Novica Rakicevic ◽  
Djuro Misljenovic

The aim of this work was to examine the disproportionation reaction of iodous acid, HOIO, in aqueous 0.18 mol/dm3H2SO4 solution, by spectrophotometric measurements of the absorbance. The absorbing HgI+-ion species were generated during the observed disproportionation process. The specific rate constants of disproportionation were calculated in the temperature range from 12 to 30 ?C. The average values ranged from 1.20 to 2.94 mol-1dm3 s-1, respectively. In addition, the values of the activation energies were determined by a graphical method. An average value of 71.20 kJ/mol was found for the chosen temperature interval.



1959 ◽  
Vol 37 (5) ◽  
pp. 953-965 ◽  
Author(s):  
S. Sato ◽  
R. J. Cvetanović

The effect of the presence of nitrogen, oxygen, and nitric oxide on the reaction between cis-2-pentene and oxygen atoms has been investigated at room temperature (25 ± 2 °C). For production of oxygen atoms use was made of mercury-photosensitized decomposition of nitrous oxide and of the photolysis of nitrogen dioxide at 3660 Å.In the N2O work, the presence of molecular oxygen induced the formation of acetaldehyde, propanal, methanol, and ethanol. In the NO2 work, the amounts of acetaldehyde, propanal, and ethyl nitrate formed increased rapidly with increasing pressure of molecular oxygen. Possible reaction mechanisms for the formation of these compounds are discussed.Additional information was obtained on the pressure-independent fragmentation in the reaction of oxygen atoms with cis-2-pentene.



1956 ◽  
Vol 34 (6) ◽  
pp. 775-784 ◽  
Author(s):  
R. J. Cvetanović

Reaction of oxygen atoms, produced by mercury photosensitized decomposition of nitrous oxide, with acetaldehyde has been studied at room temperature. The major products of the reaction are water and biacetyl and the only primary process appears to be[Formula: see text]followed by[Formula: see text]and[Formula: see text]At room temperature oxygen atoms react with acetaldehyde 0.7 ± 0.1 times as fast as with ethylene, so that the activation energy of reaction [1] is likely to be close to 3 kcal./mole.



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