scholarly journals The Pyrolysis of Tetramethyltin

1972 ◽  
Vol 50 (1) ◽  
pp. 50-54 ◽  
Author(s):  
R. P. Johnson ◽  
S. J. W. Price
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
Flow System ◽  
Heterogeneous Reaction ◽  
Methyl Radicals ◽  
Product Analysis ◽  
First Order ◽  
Carrier Flow ◽  
Pressure Limit

The pyrolysis of tetramethyltin has been studied in a toluene carrier flow system from 803–941 °K using total pressures of 10.6 to 52.4 mm. Contact times varied from 0.49 to 13.8 s and the amount of decomposition from 1.35–98.7%. The progress of the reaction was followed by measuring the amount of methane, ethane, ethylene, and ethylbenzene formed. No appreciable heterogeneous reaction was detected and the first order rates constants appear to have been determined at the high pressure limit. The quantity of undecomposed alkyl was also measured and was found to be in agreement with the product analysis if four methyl radicals are released for each molecule undergoing reaction.Least squares analysis gives[Formula: see text]with an estimated uncertainty in E of ± 1 kcal mol−1. The activation energy should be a good approximation to D[(CH3)3Sn—CH3].

The pyrolysis of trimethylarsine

1970 ◽  
Vol 48 (20) ◽  
pp. 3209-3212 ◽  
Author(s):  
S. J. W. Price ◽  
J. P. Richard
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
Rate Constants ◽  
Flow System ◽  
Heterogeneous Reaction ◽  
Methyl Radicals ◽  
Product Analysis ◽  
First Order ◽  
Carrier Flow ◽  
Pressure Limit

The pyrolysis of trimethylarsine has been studied in a toluene carrier flow system from 764 to 858 °K using total pressures from 6.35 to 35.5 mm. Contact times varied from 0.9 to 3.7 s and the amount of decomposition, from 1.2 to 73 %. The progress of the reaction was followed by measuring the amount of methane, ethane, ethylene, and ethylbenzene formed. No heterogeneous reaction was detected and the first order rate constants appear to have been determined at approximately the high pressure limit. In seven runs the undecomposed alkyl was also measured. The quantity found was in agreement with the product analysis if three methyl radicals are released for each molecule undergoing reaction.Least squares analysis of the results gives[Formula: see text]The activation energy should be a good approximation to D[(CH3)2As—CH3]. The product analysis and the values of k4/k51/2 are consistent with the simple consecutive release of three methyl radicals but thermodynamic and kinetic considerations may preclude this possibility.

Determination of Conditions for the Suppression of CH3 + Sb(CH3)2→Sb(CH3)3 and Evaluation of D[(CH3)2Sb—CH3]

1972 ◽  
Vol 50 (7) ◽  
pp. 966-971 ◽  
Author(s):  
S. J. W. Price ◽  
J. P. Richard
Keyword(s):  
Activation Energy ◽  
Least Squares ◽  
Flow System ◽  
Heterogeneous Reaction ◽  
Methyl Radicals ◽  
Product Analysis ◽  
Temperature Range ◽  
Carrier Flow

The pyrolysis of trimethylantimony has been studied in a toluene carrier flow system over the temperature range 690–803 °K (total pressures 3.6–173.4 mm, contact times 1.0–13.5 s, decomposition 3.9–89.5%). The progress of the reaction was followed by measuring the amount of methane, ethane, and ethylbenzene formed. In 23 runs the undecomposed alkyl was also determined. The quantity found was in agreement with that expected from the product analysis if three methyl radicals are released for each molecule undergoing reaction. No heterogeneous reaction was detected.Deuterium labeling led to the conclusion that regeneration of the parent alkyl occurred during the course of the decomposition. This regeneration reaction was effectively eliminated by working at toluene pressures above 150 mm. Least squares analysis of the results obtained under conditions where regeneration should not be important givenLog10k/s−1 = 15.33 − (55 900 ± 1 000)/2.3RTThe activation energy should be a good approximation to D[(CH3)2Sb—CH3].Significant decomposition of SbCH3 probably does not occur. It seems most likely that free Sb is formed via 2Sb(CH3) → Sb(CH3)2 + Sb.

The Pyrolysis of Trimethylthallium and Evaluation of D[(CH3)2Tl—CH3]

1973 ◽  
Vol 51 (9) ◽  
pp. 1397-1401 ◽  
Author(s):  
S. J. Price ◽  
J. P. Richard ◽  
R. C. Rumfeldt ◽  
M. G. Jacko
Keyword(s):  
Contact Time ◽  
Total Pressure ◽  
Flow System ◽  
Heterogeneous Reaction ◽  
Product Analysis ◽  
Carrier Flow

The pyrolysis of trimethylthallium has been studied in a mercury free toluene carrier flow system (452–536 °K, total pressure 6.7–39.3 mm, contact time 0.9–5.1 s, 5.4–90.2% decomposition). In a vessel cleaned with boiling concentrated HNO3 and coated by decomposing 0.1 g Tl(CH3)3 no heterogeneous reaction could be detected. The extent of reaction measured by product analysis (CH4, C2H6, C6H5C2H5) assuming three CH3 per Tl(CH3)3 undergoing reaction 1

THE PYROLYSIS OF TRIMETHYLTHALLIUM

1965 ◽  
Vol 43 (7) ◽  
pp. 1961-1967 ◽  
Author(s):  
M. G. Jacko ◽  
S. J. W. Price
Keyword(s):  
Activation Energy ◽  
Rate Constant ◽  
Total Pressure ◽  
Flow System ◽  
Total Darkness ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
Homogeneous Process ◽  
Carrier Flow ◽  
Reaction Proceeds

The pyrolysis of trimethylthallium has been studied in a toluene carrier flow system from 458 to 591 °K using total pressures from 5.6 to 33.0 mm. The progress of the reaction was followed by measuring the amount of methane, ethane, ethylene, and ethylbenzene formed and, in 21 runs, by direct thallium analysis. All preparative and kinetic work was carried out in total darkness where possible. A shielded 10 W lamp was used when some illumination was necessary.The decomposition is approximately 80% heterogeneous in an unconditioned vessel and 14–27% heterogeneous in a vessel pretreated with hot 50% HF for 10 min. The reaction proceeds by the simple consecutive release of three methyl radicals. The rate constant depends only slightly on the total pressure in the system so that the activation energy of the homogeneous process, 27.4 kcal/mole, may be equated to D[(CH3)2Tl—CH3].

Determination of D[(CH3)3Pb—CH3] by the Toluene Carrier Method

1972 ◽  
Vol 50 (16) ◽  
pp. 2639-2641 ◽  
Author(s):  
K. M. Gilroy ◽  
S. J. Price ◽  
N. J. Webster
Keyword(s):  
Least Squares ◽  
Flow System ◽  
Methyl Radicals ◽  
Product Analysis ◽  
Method Of Least Squares ◽  
Temperature Range ◽  
Carrier Flow

The pyrolysis of tetramethyl lead has been studied in a toluene carrier flow system over the temperature range 671–753 °K (contact times 0.72–1.67 s, 3–77% decomposition). The reaction was followed by measuring the amount of methane, ethane, and ethylbenzene formed. Comparison of the extent of reaction based on product analysis and on alkyl recovery indicates that approximately four methyl radicals are released for each molecule undergoing reaction 1.[Formula: see text]The method of least squares gives k1 = 5.0 × 1014 exp (−49 400/RT) sB1 with an estimated uncertainty of ± 1 000 cal mol−1 in E1. Under the conditions used E1 should be a reasonable measure of D[(CH3)3Pb—CH3].

The reaction of methyl radicals with neopentane in flow photolysis at 607–823 K

1984 ◽  
Vol 62 (6) ◽  
pp. 1203-1206 ◽  
Author(s):  
Hiroshi Furue ◽  
Kim C. Manthorne ◽  
Philip D. Pacey
Keyword(s):  
Heat Capacity ◽  
High Pressure ◽  
Arrhenius Plot ◽  
Flow System ◽  
Rate Coefficients ◽  
Methyl Radicals ◽  
Large Excess ◽  
Arrhenius Parameters ◽  
Temperature Range ◽  
Pressure Limit

Acetone was photolyzed in the presence of a large excess of neopentane in a flow system at total pressures between 7 and 150 Torr and at 607–823 K. For reactions[Formula: see text]and[Formula: see text]the quotient of rate coefficients, k12/k2, was calculated from CH4 and C2H6 yields and was extrapolated to the high pressure limit, k12/k2,x. Taking k2,x as 2.2 × 1010 L mol−1 s1, Arrhenius parameters for reaction [1] were found to be: log10A (L mol−1 s−1) = 10.0 ± 0.1, EA = 62( ± 2) kJ mol−1. In combination with data from the literature for the temperature range 365–953 K, the Arrhenius plot for k1/k2,x1/2 was strongly curved, with a heat capacity of activation of 71 ± 4 J K−1 mol−1.

Kinetics and Activation Parameters for the Alkaline Aqueous Rearrangement of Trichorfon [O,O-Dimethyl-(2,2,2-Trichloro-1-Hydroxyethyl) Phosphonate] to Dichlorvos [O,O-Dimethyl-O-(2,2-Dichloroethenyl)Phosphate]

2001 ◽  
Vol 36 (3) ◽  
pp. 589-604 ◽  
Author(s):  
Julian M. Dust ◽  
Christopher S. Warren
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
Activation Parameters ◽  
Base Catalysis ◽  
Rearrangement Product ◽  
Exponential Factor ◽  
First Order ◽  
Pseudo First Order ◽  
Order Plot ◽  
Kinetics Of

Abstract The kinetics of the alkaline rearrangement of O,O-dimethyl-(2,2,2-trichloro-1- hydroxyethyl)phosphonate, (trichlorfon, 1), the active insecticidal component in such formulations as Dylox, was followed at 25±0.5°C by high pressure liquid chromatography (UV-vis detector, 210 nm). The rearrangement product, O,Odimethyl- O-(2,2-dichloroethenyl)phosphate (dichlorovos, 2), which is a more potent biocide than trichlorfon, undergoes further reaction, and the kinetics, consequently, cannot be treated by a standard pseudo-first-order plot. A two-point van't Hoff (initial rates) method was used to obtain pseudo-first-order rate constants (kѱ) at 25, 35 and 45°C: 2.6 × 10-6, 7.4 × 10-6 and 2.5 × 10-5 s-1, respectively. Arrhenius treatment of this data gave an activation energy (Ea) of 88 kJ·mol-1 with a pre-exponential factor (A) of 5.5 × 109 s-1. Kinetic trials at pH 8.0 using phosphate and tris buffer systems show no buffer catalysis in this reaction and indicate that the rearrangement is subject to specific base catalysis. Estimates are reported for pseudo-first-order half-lives for trichlorfon at pH 8.0 for environmental conditions in aqueous systems in the Corner Brook region of western Newfoundland, part of the site of a recent trichlorfon aerial spray program.

PRESSURE-INDEPENDENT FLOW SYSTEM PYROLYSIS OF DIMETHYL CADMIUM

1965 ◽  
Vol 43 (7) ◽  
pp. 1929-1933 ◽  
Author(s):  
M. Krech ◽  
S. J. Price
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
Rate Constants ◽  
Flow System ◽  
Kcal Mole ◽  
Pressure Independent

The pyrolysis of CdMe2 has been investigated in a benzene carried flow system using temperatures from 743 °K to 800 °K and pressures from 1.63 cm to 16.2 cm. High pressure limiting rate constants were obtained above approximately 8 cm pressures. The high pressure activation energy, E0, of 48.8 ± 1 kcal/mole is identified with D(MeCd—Me) within the limits D < E0 < D + RT.

Die Kinetik des Zerfalls von tert. Butylperoxypivalat bei hohen Drücken und Temperaturen / The Kinetics of the Decomposition of tert.Butylperoxypivalate up to High Pressures and Temperatures

1981 ◽  
Vol 36 (12) ◽  
pp. 1371-1377 ◽  
Author(s):  
M. Buback ◽  
H. Lendle
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
High Pressures ◽  
Activation Volume ◽  
Rate Law ◽  
First Order ◽  
Order Rate ◽  
High Pressures And Temperatures ◽  
Kinetics Of

AbstractThe decomposition of tert. butylperoxypivalate dissolved in n-heptane has been measured ir-spectroscopically in optical high-pressure cells up to 2000 bar at temperatures between 65 °C and 105 °C. The reaction follows a first order rate law with an activation energy Ea = 122.3 ±3.0 kJ · mol-1 and an activation volume ⊿V≠ = 1.6 ± 1.0 cm3 mol-1 .

The thermal isomerisation of allyl isocyanide

1979 ◽  
Vol 57 (18) ◽  
pp. 2482-2483 ◽  
Author(s):  
Marsha T. J. Glionna ◽  
Huw O. Pritchard
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
Gas Phase ◽  
Frequency Factor ◽  
First Order ◽  
Temperature Range

The thermal isomerisation of allyl isocyanide to allyl cyanide has been studied in the gas phase over the temperature range 130–200 °C. The reaction is homogeneous and first order, and at high pressure (20 Torr) has an activation energy of 40.8 ± 0.6 (2sdm) kcal mol−1; the corresponding range of frequency factor is 1014.77±0.30 s−1.

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