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.

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].

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.

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.

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].

THE PYROLYSIS OF TOLUENE

1962 ◽  
Vol 40 (7) ◽  
pp. 1310-1317 ◽  
Author(s):  
S. J. Price
Keyword(s):  
Activation Energy ◽  
Rate Constant ◽  
Rate Constants ◽  
Contact Time ◽  
Flow System ◽  
Kcal Mole ◽  
Homogeneous Process ◽  
First Order ◽  
Order Rate ◽  
Toluene Concentration

The pyrolysis of toluene has been studied in a flow system from 913 to 1143 °K. First-order rate constants are independent of the toluene concentration but decrease approximately 9% when the contact time is reduced from 1.0 to 0.41 second. Increasing the contact time from 1.0 second to 2.07 seconds does not affect the rate constant. The overall rate has been resolved into homogeneous and heterogeneous components. It is suggested that the activation energy of the homogeneous process, 85 kcal/mole, may be associated with D(C6H5CH2—H).

PRESSURE-INDEPENDENT FLOW SYSTEM PYROLYSIS OF DIMETHYL MERCURY

1963 ◽  
Vol 41 (2) ◽  
pp. 224-227 ◽  
Author(s):  
M. Krech ◽  
S. J. Price
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
Rate Constants ◽  
Flow System ◽  
Kcal Mole ◽  
Carrier System ◽  
Pressure Independent

The pyrolysis of HgMe2 has been investigated in a benzene carrier system using temperatures from 693 °K to 800 °K and pressures from 0.36 cm to 26.0 cm. High-pressure limiting rate constants were obtained above approximately 10 cm pressure. The high-pressure activation energy, E0, of 53.7 ± 0.5 kcal/mole is identified with D(MeHg—Me) within the limits D < E0 < D + RT.

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.

scholarly journals KINETICS OF PALM OIL TRANSESTERIFICATION IN METHANOL WITH POTASSIUM HYDROXIDE AS A CATALYST

2010 ◽  
Vol 8 (2) ◽  
pp. 219-225
Author(s):  
Yoeswono Yoeswono ◽  
Triyono Triyono ◽  
Iqmal Tahir
Keyword(s):  
Activation Energy ◽  
Palm Oil ◽  
Rate Constants ◽  
Potassium Hydroxide ◽  
Catalyst Concentration ◽  
Time Interval ◽  
Pseudo First Order Reaction ◽  
Exponential Factor ◽  
Potassium Methoxide ◽  
First Order

A study on palm oil transesterification to evaluate the effect of some parameters in the reaction on the reaction kinetics has been carried out. Transesterification was started by preparing potassium methoxide from potassium hydroxide and methanol and then mixed it with the palm oil. An aliquot was taken at certain time interval during transesterification and poured into test tube filled with distilled water to stop the reaction immediately. The oil phase that separated from the glycerol phase by centrifugation was analyzed by 1H-NMR spectrometer to determine the percentage of methyl ester conversion. Temperature and catalyst concentration were varied in order to determine the reaction rate constants, activation energies, pre-exponential factors, and effective collisions. The results showed that palm oil transesterification in methanol with 0.5 and 1 % w/w KOH/palm oil catalyst concentration appeared to follow pseudo-first order reaction. The rate constants increase with temperature. After 13 min of reaction, More methyl esters were formed using KOH 1 % than using 0.5 % w/w KOH/palm oil catalyst concentration. The activation energy (Ea) and pre-exponential factor (A) for reaction using 1 % w/w KOH was lower than those using 0.5 % w/w KOH.   Keywords: palm oil, transesterification, catalyst, first order kinetics, activation energy, pre-exponential factor

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