Kinetics of the free-radical chain chlorination of hydrocarbons by tert-butyl hypochlorite

1972 ◽  
Vol 94 (13) ◽  
pp. 4603-4608 ◽  
Author(s):  
Andreas A. Zavitsas ◽  
Blank John D.
Keyword(s):  
Free Radical ◽  
Radical Chain ◽  
Tert Butyl ◽  
Kinetics Of

Kinetics of Ionic and Free Radical Chain Reactions in Radiation Chemistry

1969 ◽  
Vol 6 (5) ◽  
pp. 466-473
Author(s):  
Donald H. Martin ◽  
Robert B. Taylor ◽  
Ffrancon Williams
Keyword(s):  
Free Radical ◽  
Radiation Chemistry ◽  
Radical Chain ◽  
Chain Reactions ◽  
Kinetics Of

scholarly journals Inhibiting oxidation and enhancing absorption characteristics of sodium sulfite for SO2 removal from the non-ferrous smelting flue gas

2020 ◽  
Vol 26 (2) ◽  
pp. 200043-0
Author(s):  
Yongpeng Ma ◽  
Dongli Yuan ◽  
Xiaojing Zhang ◽  
Zan Qu ◽  
Wenjun Huang
Keyword(s):  
Free Radical ◽  
Flue Gas ◽  
Absorption Capacity ◽  
Inhibition Mechanism ◽  
Radical Chain ◽  
Consumption Rates ◽  
Free Radical Chain Reaction ◽  
Kinetics Of ◽  
Radical Chain Reaction ◽  
Absorption Characteristics

In this work, we investigated the absorption characteristics of SO2 and the effect of inhibitors on the desulfurization performances of Na2SO3. The results showed that the NO2 had a competitive effect with SO2 on SO32- which resulted in a significant decrease in the absorption capacity of SO2. O2 in the flue gas could decrease the absorption capacity of SO2 due to the oxidation of Na2SO3. Besides, Na2S2O3 had more excellent inhibiting effect on the oxidation of SO32-; the inhibition mechanism is understood on the basis of the free radical chain reaction, whereby S2O32- combined with the sulfite free radical to form an inert substance, thus, quenching the reaction of free radical with the dissolved oxygen and invariably inhibiting the oxidation of SO32-. Furthermore, the intrinsic and the apparent oxidation kinetics of Na2SO3 oxidation process with Na2S2O3 were investigated to explain the relationships between consumption rates of SO32- and the absorption capacities of SO2 under different components in flue gas and absorption solution.

The antioxidant activities of phenolic antioxidants in free radical peroxidation of phospholipid membranes

1990 ◽  
Vol 68 (12) ◽  
pp. 2258-2269 ◽  
Author(s):  
Lawrence Ross Coates Barclay ◽  
Kimberly Ann Baskin ◽  
Kelly Andrea Dakin ◽  
Steven Jefffrey Locke ◽  
Melinda Ruth Vinqvist
Keyword(s):  
Hydrogen Bonding ◽  
Free Radical ◽  
Rate Constants ◽  
Antioxidant Activities ◽  
Hydrogen Abstraction ◽  
Peroxyl Radicals ◽  
Phenolic Antioxidants ◽  
Inhibition Rate ◽  
Radical Chain ◽  
Tert Butyl

Autoxidation of dilinoleoylphosphatidylcholine (DLPC) bilayers photoinitiated by benzophenone takes place by a free radical chain mechanism according to product studies of the cis, trans and trans, trans-9- and -13-linoleate hydroperoxides formed and kinetic studies of the reaction order as a function of light intensity. The absolute rate constant for hydrogen abstraction from DLPC bilayers by peroxyl radicals is found to be 36.1 M−1 s−1 at 37 °C. Preliminary measurements of activities of phenolic antioxidants, α-tocopherol (α-T), 2,2,5,7,8-pentamethyl-6-hydroxychroman (PMHC), 2,5,7,8-tetramethyl-6-hydroxychroman-2-carboxylate (Trolox), and 2,6-di-tert-butyl-4-methylphenol (BHT) by oxygen uptake studies during inhibition periods using photoinitiation gave uncorrected inhibition rate constants, Kinh, for α-T, PMHC, and Trolox several orders of magnitude lower than observed earlier in chlorobenzene. Three series of phenolic antioxidants, (a) polyalkyl-6-hydroxychromans, (b) polyalkyl-4-methoxyphenols, and (c) trialkylphenols, were examined for their antioxidant activities in DLPC membranes during thermally initiated autoxidation by azobis-2,4-dimethylvaleronitrile (DMVN). The corrected inhibition rate constants, kinh, observed in (a), α-T (5.8 × 103), PMHC (17.8 × 103), Trolox (5.8 × 103), 2,2-dimethyl-5,7-diisopropyl-6-hydroxychroman, 4a (55 × 103), and 2,2,5-trimethyl-7-tert-butyl-6-hydroxychroman, 5a (61 × 103) M−1 s−1, are dramatically lower, by several orders of magnitude, than those measured earlier in chlorobenzene and significantly lower (about 1/40–1/10) than those measured in solution in tert-butyl alcohol and less than kinh measurements (1/2–1/5) in aqueous SDS micelles. The kinh values for series (b) were 2,3,5,6-tetramethyl-4-methoxyphenol (TTMMP) (2.1 × 103), 2,3,6-trimethyl-4-methoxyphenol (TMMP) (10.4 × 103), and 2,6-di-tert-butyl-4-methoxyphenol (DBHA) (27.5 × 103) M−1 s−1 and for (c) were 2,6-di-tert-butyl-4-methylphenol (BHT) (3.7 × 103) and 2,4,6-trimethylphenol (TMP) (0.56 × 103) M−1 s−1. The results show an overall leveling and depression of antioxidant activities in DLPC membranes in the series (a), (b), (c) compared to those reported in solution in chlorobenzene, where large differences were attributed to steroelectronic effects of the para ether oxygen stabilizing the derived phenoxyl radicals in (a) and (b) types. The results in aqueous micellar and membrane systems are interpreted in terms of polar solvation effects. Hydrogen bonding by water at both the ether and phenolic groups decreases the activity of the (a) series. Hydrogen bonding at the phenolic hydroxyl appears to be the more significant factor since steric hindrance to H-bonding at hydroxyl allows 4a and 5a to be the most active antioxidants of the α-tocopherol series (a) and DBHA to be the most active antioxidant of the (b) series. Keywords: antioxidant activities, phenols, membranes, peroxidation, kinetics.

Kinetics of the thermal reactions of ethylene. Part II. Ethylene–ethane mixtures

1968 ◽  
Vol 46 (14) ◽  
pp. 2427-2433 ◽  
Author(s):  
M. L. Boyd ◽  
M. H. Back
Keyword(s):  
Free Radical ◽  
Product Formation ◽  
Radical Chain ◽  
Thermal Reactions ◽  
Temperature Range ◽  
Initiation Step ◽  
Chain Polymerization ◽  
Main Effects ◽  
Kinetics Of ◽  
Simplified Mechanism

Mixtures of ethane and ethylene have been pyrolyzed in the temperature range 563–600 °C and at pressures from 30–60 cm. The products were similar to those obtained from the pyrolysis of ethylene by itself, described m Part I, with a marked increase in the yields of the saturated products. The initial rates of product formation and the dependence of these rates on the concentration of ethane suggest that the initiation step is the same as that proposed in the pyrolysis of ethylene alone, viz.[Formula: see text]and that the reaction[Formula: see text]is not an important source of radicals. A simplified mechanism is outlined to account for the main effects of ethane on the free radical chain polymerization.

THE KINETICS OF THE DECOMPOSITION REACTIONS OF THE LOWER PARAFFINS: VII. THE NITRIC OXIDE INHIBITED DECOMPOSITION OF ETHANE

1940 ◽  
Vol 18b (11) ◽  
pp. 351-357 ◽  
Author(s):  
E. W. R. Steacie ◽  
Gerald Shane
Keyword(s):  
Nitric Oxide ◽  
Activation Energy ◽  
Thermal Decomposition ◽  
Free Radical ◽  
Radical Chain ◽  
Decomposition Reactions ◽  
Rearrangement Mechanism ◽  
Chain Lengths ◽  
Kinetics Of

An investigation has been made of the nitric oxide inhibited thermal decomposition of ethane. Apparent chain lengths of 2.4 to 5 are found at temperatures from 640° to 565 °C. The activation energy of the inhibited reaction is found to be 77.3 Kcal. The results are discussed and it is concluded that the thermal decomposition of ethane proceeds mainly by a rearrangement mechanism and that free-radical chain mechanisms for the ethane decomposition are untenable.

The oxidation of phenol and chlorophenols by manganate(VI) ion

1981 ◽  
Vol 59 (18) ◽  
pp. 2780-2786 ◽  
Author(s):  
Donald G. Lee ◽  
Carlos F. Sebastián
Keyword(s):  
Free Radical ◽  
Fractional Order ◽  
Reaction Rate ◽  
Acid Catalysis ◽  
Chain Mechanism ◽  
Radical Chain ◽  
First Order ◽  
Alkaline Conditions ◽  
Oxidation Of Phenol ◽  
Kinetics Of

The kinetics of the oxidation of phenol and three chlorophenols have been studied under alkaline conditions. Although the reaction is first order with respect to the oxidant it exhibits a fractional order with respect to the substrates, thus suggesting a free radical chain mechanism (eqs. [3]–[7]). The inverse dependence of the reaction rate on base concentration has been attributed to acid catalysis of the chain initiating step.

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