Kinetics of pyridine degradation along with toluene and methylene chloride with

1998 ◽  
Vol 18 (4) ◽  
pp. 303
Author(s):  
B. Uma ◽  
S. Sandhya
Keyword(s):  
Methylene Chloride ◽  
Pyridine Degradation ◽  
Kinetics Of

The non-stationary polymerization of styrene by HCIO 4 in CH 2 CI 2

1976 ◽  
Vol 351 (1667) ◽  
pp. 551-568 ◽  
Keyword(s):  
Rate Constants ◽  
Methylene Chloride ◽  
Dissociation Constants ◽  
Propagation Rate ◽  
Polymer Chains ◽  
Stage I ◽  
Electrically Conducting ◽  
Steady Stage ◽  
Ionic Components ◽  
Kinetics Of

The non-stationary precursor reaction (stage I) in the polymerization of styrene by perchloric acid in methylene chloride has been examined, by stopped-flow methods over the range 0 to –80 °C. At all temperatures there is evidence of a transient, electrically conducting, intermediate species, absorbing at 340 nm, which reaches its peak concentration at times ranging from 0.1s at 0° C to 0.5–3s at –80 °C (variable with reagent concentra­tions). At the low monomer concentrations (< 0.2M) accessible to the technique, stage I can be quantitatively discriminated from the subsequent steady stage II only below ca . –60 °C. At these low temperatures, contrary to expectations, the conversion during stage I proves to be by a dual mech­anism, the ionic reaction producing no more than about half the mass of polymer and a much smaller fraction of the number of polymer chains. The overall time-scale of stage I appears to be determined primarily by that of removal of free HCIO 4 by the non-ionic mechanism, rather than by the kinetics of the ionic polymerisation. The overall conversions cannot therefore be analysed to yield ionic rate constants. In reactions in presence of the salt n -Bu 4 NCIO 4 , the instantaneous rates can be separated into their non-ionic and ionic components, and approxi­mate values derived for the paired-ion propagation rate constants. k ± p 2000 at –80 °C; 4000–5000 at –60 °C; (unit: dm 3 mol –1 s –1 ). A more speculative analysis of the rates in salt-free systems permits estimates of the free ion propagation constants some 10–20 times the above values, and of ion-pair dissociation constants in the region of 1–5 x 10 –7 mol dm –3 at –60 to –80 °C.

Kinetics of Methylene Chloride Hydrolysis and the Salt Effect under Hydrothermal Conditions

2001 ◽  
Vol 40 (4) ◽  
pp. 1026-1031 ◽  
Author(s):  
Yoshito Oshima ◽  
Budianto Bijanto ◽  
Seiichiro Koda
Keyword(s):  
Methylene Chloride ◽  
Salt Effect ◽  
Hydrothermal Conditions ◽  
Kinetics Of

The thermal oxidation of methylene chloride

1959 ◽  
Vol 250 (1261) ◽  
pp. 197-211 ◽  
Keyword(s):  
Thermal Decomposition ◽  
Chain Length ◽  
Methylene Chloride ◽  
Decomposition Reaction ◽  
Average Chain Length ◽  
Static System ◽  
Chain Process ◽  
Branched Chain ◽  
Considerable Detail ◽  
Kinetics Of

A study of the kinetics of the slow oxidation of methylene chloride has been made using a static system and the results of this are compared with those of flow-system experiments in which the composition of the reacting system was determined in considerable detail by gaschromatographic analysis. The reaction shows all the symptoms of a degenerately branched chain process and is similar to the corresponding thermal decomposition reaction in many respects. Several of the chlorinated hydrocarbon minor products are identical with those found in the thermal decomposition and this, together with kinetic evidence, suggests that the primary chain is the same in both reactions, oxygen intervening only in the conversion of the intermediate, dichlorethylene, to the end products HCl and carbon monoxide, and in the branching step, through which it modifies the overall rate. As in the thermal decomposition several of the organic minor products are susceptible to attack by chlorine atoms participating in the main chain and this prevents an accurate evaluation of the chain length by measurement of the rate of formation of termination products. The average chain length, however, appears to be of the order of ten. Methylene chloride + oxygen mixtures show a single explosion limit above about 600° C, which obeys the Semenov equation log 10 p = A / T + B , A being a constant for the system and B depending on the geometry of the vessel.

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