Formate decarboxylation kinetic parameters

Kinetic parameters for formation and decarboxylation of carbonato-rhod-ium(III) complexes are given in Tables 5.16 and 5.17. In acid solution, the cis-[Rh(en)2(C03)] cation loses carbon dioxide slowly. Rate constants and activation parameters (A// and A5 ) are reported for the two paths indicated by ... 

Rate constants and activation parameters are also given for loss of carbon dioxide from the intermediate d5-[Rh(en)2(C03H)(OH2)]. Here the rhodium(III) system has two advantages over its cobalt(III) counterpart, for not only is it possible to obtain kinetic data for the monodentate bicarbonato intermediate but also there is no concomitant isomerization to complicate the carbon dioxide loss kinetics in the rhodium(III) case. In the reverse direction, kinetic parameters were obtained for the reaction of c/5-[Rh(en)2(OH2)(OH)] and of d5-[Rh(en)2(OH)2] with carbon dioxide-(bi)carbonate. The products are cw-[Rh(en)2(C03)(0H2)] and d5-[Rh(en)2(C03)(0H)] there is no mention of a bidentate carbonato product. Kinetics of decarboxylation of the new complexes trans-[Rh(en)2(C03)(0H2)] and rra 5-[Rh(en)2(C03)2]" have been reported, with values for rate constants and activation parameters given. The bis(carbonato) complex loses both carbonate ligands at low pHs, but only one carbonate when pH > 6.5. The kinetics of the reverse carbonate-formation reactions, from trans-... 

The kinetics and mechanisms of gas-phase elimination of ethyl 1-piperidinecarboxyl-ate, ethyl pipecolinate, and ethyl 1-methylpipecolinate has been determined in a static reaction system.9 The reactions proved to be homogeneous, unimolecular, and obey a first-order rate law. The first step of decomposition of these esters is the formation of the corresponding carboxylic acids and ethylene. The acid intermediate undergoes a very fast decarboxylation process. The mechanism of these elimination reactions has been suggested on the basis of the kinetic and thermodynamic parameters. 

Experimental data of stearic acid decarboxylation in a laboratory-scale fixed bed reactor for formation of heptadecane were evaluated studied with the aid of mathematical modeling. Reaction kinetics, catalyst deactivation, and axial dispersion were the central elements of the model. The effect of internal mass transfer resistance in catalyst pores was found negligible due to the slow reaction rates. The model was used for an extensive sensitivity study and parameter estimation. With optimized parameters, the model was able to describe the experimentally observed trends adequately. A reactor scale-up study was made by selecting the reactor geometry (diameter and length of the reactor, size and the shape of the catalyst particles) and operating conditions (superficial liquid velocity, temperature, and pressure) in such a way that nonideal flow and mass and heat transfer phenomena in pilot scale were avoided. 

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