scholarly journals Pyrolysis of azetidinones. Part 2. Kinetics and mechanism of thermolysis of β-lactams and β-thiolactams

2016 ◽  
Vol 94 (9) ◽  
pp. 788-793 ◽  
Author(s):  
Nouf S. Al-Hamdan ◽  
Alya M. Al-Etaibi ◽  
Rasha F. Al-Bashir ◽  
Yahia A. Ibrahim ◽  
Nouria A. Al-Awadi ◽  
...  
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Kinetics And Mechanism ◽  
Energy Of Activation ◽  
The Novel ◽  
Temperature Range ◽  
Entropy Of Activation ◽  
Kinetics Of ◽  
Thermolysis Reaction

The kinetics of the gas-phase thermolysis reaction of seven β-lactams and their thione analogues were investigated over the temperature range 533–603 K for the β-lactams and 463–542 K for the β-thiolactams. The average values of the energy of activation (Ea) (kJ mol−1) and Arrhenius log A (s–1) were, respectively, 170.8 ± 18.6 and 12.4 ± 1.6 for the lactams and 131.7 ± 18.2 and 11.0 ± 2.0 for the thione analogues. The entropy of activation (ΔS#) was negative for of the substrates and slightly positive for three. The rate constants (k) (s−1) were calculated for 510 K and compared for the two series of azetidinones. The effects of substituents on rates and the novel role played by the C=O and C=S moieties on the relative reactivities of the cyclic amides are rationalized on the basis of a formal retro[2+2]cycloaddition mechanism used earlier to explain the products of the gas-phase thermolysis reaction of the present azetidinones.

scholarly journals Kinetics of the gas-phase reactions of OH radicals with alkanes and cycloalkanes

2003 ◽  
Vol 3 (6) ◽  
pp. 2233-2307 ◽  
Author(s):  
R. Atkinson
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Relative Rate ◽  
Oh Radicals ◽  
Gas Phase Reactions ◽  
Temperature Dependent ◽  
Temperature Range ◽  
Dependent Rate ◽  
Temperature Ranges ◽  
Kinetics Of

Abstract. The available database concerning rate constants for gas-phase reactions of the hydroxyl (OH) radical with alkanes through early 2003 is presented over the entire temperature range for which measurements have been made (~180-2000 K). Measurements made using relative rate methods are re-evaluated using recent rate data for the reference compound (generally recommendations from this review). In general, whenever more than one study has been carried out over an overlapping temperature range, recommended rate constants or temperature-dependent rate expressions are presented. The recommended 298 K rate constants, temperature-dependent parameters, and temperature ranges over which these recommendations are applicable are listed in Table 1.

Kinetics of the Nitrosation of Pyrrolidine and Proline

1974 ◽  
Vol 52 (7) ◽  
pp. 1050-1053 ◽  
Author(s):  
A. Okany ◽  
T. F. Massiah ◽  
L. J. Rubin ◽  
K. Yates
Keyword(s):  
Rate Constants ◽  
Nitroso Compounds ◽  
Meat Processing ◽  
Temperature Range ◽  
Buffer Solutions ◽  
Entropy Of Activation ◽  
Kinetics Of

The kinetics of the nitrosation of pyrrolidine and proline have been investigated in buffer solutions of mildly acidic pH's in the temperature range 40–100 °C. The rate constants were determined and the enthalpy and the entropy of activation were calculated for both reactions. Examples are presented in which are estimated the maximum amounts of nitroso compounds formed under conditions relevant to meat processing.

scholarly journals Kinetics of the gas-phase reactions of OH radicals with alkanes and cycloalkanes

2003 ◽  
Vol 3 (4) ◽  
pp. 4183-4358 ◽  
Author(s):  
R. Atkinson
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Relative Rate ◽  
Oh Radicals ◽  
Reference Compound ◽  
Gas Phase Reactions ◽  
Temperature Dependent ◽  
Temperature Range ◽  
Dependent Rate ◽  
Kinetics Of

Abstract. The available database concerning rate constants for gas-phase reactions of the hydroxyl (OH) radical with alkanes through early 2003 is presented ove the entire temperature range for which measurements have been made (~180–2000 K). Measurements made using relative rate methods are re-evaluated using recent rate data for the reference compound (generally recommendations from this review). In general, whenever more than one study has been carried out over an overlapping temperature range, recommended rate constants or temperature-dependent rate expressions are presented.

Rate constants for the gas-phase reactions of cyclo-CXCXCF2CF2– (X=H, F) with OH radicals at a temperature range of 253–328K

2013 ◽  
Vol 572 ◽  
pp. 21-25 ◽  
Author(s):  
Xiaoqing Jia ◽  
Liang Chen ◽  
Junji Mizukado ◽  
Shuzo Kutsuna ◽  
Kazuaki Tokuhashi
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Oh Radicals ◽  
Gas Phase Reactions ◽  
Temperature Range

The Elimination Reactions of Some Alkyl Cyanides in the Gas Phase

1973 ◽  
Vol 51 (3) ◽  
pp. 366-369 ◽  
Author(s):  
P. N. Dastoor ◽  
E. U. Emovon
Keyword(s):  
Thermal Decomposition ◽  
Gas Phase ◽  
Rate Constants ◽  
Flow System ◽  
Elimination Reactions ◽  
Kinetics Of

The kinetics of the thermal decomposition of ethyl, isopropyl, and t-butyl cyanides into HCN and the corresponding defines have been studied in a seasoned silica vessel in a flow system in the absence and presence of toluene as inhibitor. The reactions are homogeneous and the unimolecular rate constants are expressible by the following Arrhenius equations:[Formula: see text]

scholarly journals The rupture of carbon-nitrogen bonds. Kinetics of the thermal decomposition of ω-azotoluene vapour

1936 ◽  
Vol 156 (888) ◽  
pp. 455-462 ◽  
Keyword(s):  
Thermal Decomposition ◽  
Energy Of Activation ◽  
Azo Compounds ◽  
Temperature Range ◽  
The Difference ◽  
Lower Temperature ◽  
Nitrogen Bonds ◽  
Kinetics Of

The energy of activation found for the benzalazine decomposition is somewhat higher than those hitherto recorded for the decompositions of azo-compounds. The difference between the azine- and azo-decompositions can only be appreciated, however, on comparing the decomposition of benzalazine with that of its aromatic azo-analogue, i . e ., ω-azotoluene. According to Thiele,* when the latter substance is heated in vacuo , gas liberation begins at 15°-180° C. C 6 H 5 . CH 2 ─ N = N ─ CH 2 . C 6 H 5 = N 2 + C 6 H 5 . CH 2 . CH 2 . C 6 H 5 . This reaction is analogous to the benzalazine decomposition (measured at 318°- 180° C), C 6 H 5 . CH = N ─ N = CH. C 6 H 5 = N 2 + C 6 H 5 . CH = CH. C 6 H 5 , and resembles the aliphatic azo-decompositions investigated by Rams-perger over the temperature range 250° - 350° C, though occurring at a lower temperature than these.

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