Degree parallel reaction

Such hydrogenolysis indicates that the following two parallel reactions occur and that their ratio will vary substantially with degree and location of methyl group in the catalytic hydrogenolysis of asymmetric diarylmethanes (Ar—CH2—Ar ) ... 

In the parallel reaction scheme (fifth row in Table 2.1), competition is observed between the two reactions when only one of the products is required and the other one is a secondary undesired or a low value product. In this case, the degree of... 

Fig. 5 shows how the discolouration developed in these semibatch experiments is correlated against conversion. At low conversion levels up to 50K, the reaction and mass transfer conditions do not affect the extent of discolouration achieved. Beyond 50K, there is some evidence that under severe conditions (ie. 3011 SO-) the degree of discolouration is accelerating. However for the purposes of initial assessment, the by-product colour can be represented by a parallel reaction where the sulphonation and discolouration reactions have similar activation energies. Brostrom s colour results are different, and shown in Fig. 5 for comparison (15). 

If the reaction rate is comparable with the rate of the local micro-mixing, similar information can be obtained from competitive parallel reactions as from competitive consecutive reactions. However, parallel reactions offer the experimenter greater degrees of freedom with respect to different feed sequences or different stoichiometric ratios. 

B and D form an addition reaction with the excited states A or A", respectively, in two linear independent steps of the reaction. In this case the correlation between the degrees of advancement is equivalent to that in the case of analogous thermal reactions treated in Section 2.4.2.1 as independent parallel reactions. If the reaction takes place according to this mechanism, the relationship will differ from that in the example given above. 

The distributor -type membrane reactor possesses different residence-time characteristics and different local concentration profiles compared to the conventional FBR. The additional degrees of freedom allow in complex networks of consecutive and parallel reactions, the selectivity and the yield to be enhanced with respect to a certain target product. The concept can be considered as an interesting option in the current attempts to improve and intensify reaction processes. 

The same applies to the oxyethylation of FAME. Thus, the reaction depends on the rate of EO transport to the liquid phase. The delivered EO is immediately consumed in successive parallel reactions giving products with various numbers of oxyethylene groups. The rate constants of the first, second, third, and nth reaction steps are denoted by Kq, k-y, and respectively. However, the contribution of the reaction depends on the process temperature and degree of oxyethylation. An increase in temperature enhances the role of diffusion, whereas an increase in oxyethylation degree has an opposite effect caused by an increased concentration of EO dissolved in the liquid phase. All this means that the computed constants cannot be considered as typical kinetic constants but only as relative estimates of consecutive reaction steps. 

Apart from SiH-methylation, attention must be paid to C-hydrogenation (that is, formation of a CHCl group as a competing and paralleling reaction). The latter compounds will increase in yield as the degree of methylation increases. This yield will therefore be determined from the amounts of MeMgCl used. Moreover, the pro-... 

The reaction can be run under differing mass ttansfer rates by changes in impeller speed and system pressure. These changes can also affect the addition time necessary for completion of gas uptake. If the yield increases with increased mass transfer (higher impeller speed and/or higher system pressure), mixing conditions are clearly demonstrated to be critical. The maximum possible yield may not have been achieved because these factors can all affect overall reaction time and the degree to which by-products can form in the films and the continuous phases in consecutive and parallel reactions. 

Although both stereoisomers yield 4 tert butylcyclohexene as the only alkene they do so at quite different rates The cis isomer reacts over 500 times faster than the trans The difference in reaction rate results from different degrees of rr bond develop ment in the E2 transition state Since rr overlap of p orbitals requires their axes to be parallel rr bond formation is best achieved when the four atoms of the H—C—C—X unit he in the same plane at the transition state The two conformations that permit this are termed syn coplanar and anti coplanar... 

For the same production capacity, the oxygen-based process requires fewer reactors, all of which operate in parallel and are exposed to reaction gas of the same composition. However, the use of purge reactors in series for an air-based process in conjunction with the associated energy recovery system increases the overall complexity of the unit. Given the same degree of automation, the operation of an oxygen-based unit is simpler and easier if the air-separation plant is outside the battery limits of the ethylene oxide process (97). 

The degree to which an electrode will influence the reaction rates is different for different electrochemical reactions, hi complex electrochemical reactions having parallel pathways, such as a reaction involving organic substances, the electrode material might selectively influence the rates of certain individual steps and thus influence the selectivity of the reaction (i.e., the overall direction of the reaction and the relative yields of primary and secondary reaction products). 

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