Reactivity differential

Expanding the square in Eq. (7.26) gives the reactive differential scattering cross section as (where we drop the initial state labels for convenience) f... 

Highly selective synthetic transformations can be performed readily by taking advantage of the che-moselectivity of SmI . It has been pointed out that there is a tremendous reactivity differential in the Bar-bier-type reaction between primary organic iodides or tosylates on the one hand, and organic chlorides on the other. As expected, selective alkylation of ketones can be accomplished by utilizing appropriately functionalized dihalides or chlorosulfonates (equation 24). Alkenyl halides and, presumably, aryl halides can also be tolerated under these reaction conditions. 

Hayes, E. F.J Walker, R. B. "Reactive differential cross sections in the rotating linear model reactions of fluorine atoms with hydrogen molecules and their isotopic variants, Zt. 

Differential and Integral Cross Sections. In Figure 7 are shown the state-to-state 1-average reactive differential cross sections for F-fH2 (degeneracy-averaged over m., summed over m and but resolved with respect to the final vibrational state v ). In each figure. 

Since most of the physical properties of the asphaltenes did not show any major differences, thermal reactivity was investigated to discern any differences which might exist in chemical reactivity. Differential scanning calorimetry and thermogravi-metric analysis as well as rapid pyrolysis were employed. The only notable features of the DSC analyses were what appeared to be glass transitions occurring at 175°C and 172°C for the crude and residuum asphaltenes, respectively. The TGA curves for the two materials were also virtually identical, differing by less than one percent volatile matter at any temperature. Both of these techniques thus indicate essentially no discemable differences in the two asphaltenes. 

Peptide synthesis. Mediated by MesAl, thiol esters condense with amines to form amides. Note the reactivity differentiation of two thiol esters in the amino acid components in the following equation. 

It is apparent that the breadth of the MWD is highly dependent on the extent of reaction (conversion) attained in these reactions, as B increases with the conversion. At low conversions, the MWD for an AB system corresponds to a Flory distribution (B 2) however, B trends toward infinity as full conversion is approached. Eor trifunctional monomers, including equally reactive A3 monomers and ABC monomers with reactivity differentials, the MWD also depends on the DP but in a different way B is proportional to DP in an A3 system, while for an ABC system it is proportional to (DP) [49, 50]. 

Attention was then directed towards the development of a one pot procedure. The success of the tethering reaction with NIS indicated a reactivity differential between the enol ether and the anomeric thiophenyl group. Choice of solvent proved to be crucial, with 1,2-dichloroethane giving the best results. 

Void coefficients were measured through the use of thln-wall aluminum tubes. The reactivity differential between the void and no-void condition was evaluated by a measurement of the change in t e reactor period between the two conditions with the core fully reflected. 

We highlight some recent work from our laboratory on reactions of atoms and radicals with simple molecules by the crossed molecular beam scattering method with mass-spectrometric detection. Emphasis is on three-atom (Cl + H2) and four-atom (OH + H2 and OH + CO) systems for which the interplay between experiment and theory is the strongest and the most detailed. Reactive differential cross sections are presented and compared with the results of quasiclassical and quantum mechanical scattering calculations on ab initio potential energy surfaces in an effort to assess the status of theory versus experiment. 

We have carried out reactive differential cross section measurements in CMB experiments [21,22] and determined the spatial distribution and energy distribution of the products from reaction (1) and (2). The results are compared with those of quasiclassical and quantum mechanical (approximate) dynamical computations on ab initio surfaces, which have been carried out by Schatz [13,25,26] and by Clary [12,26,27] at the experimental energies. 

The determination of the reactive differential cross section IC ) from quasiclassical trajectory calculations has been reviewed by Truhlar and Muckerman. Two procedures have been used in the past to display the cross section. The first is the histogram method. One serious problem with this method is that a continuous function 1(0) is being approximated by a discontinous histogram. In addition, there are problems with choosing the locations and widths of the angular bins. The second procedure is to expand 1(0) in a series of Legendre polynomials. " However, there are also problems with this method. First, it isn t certain at what point to truncate the series to minimize the uncertainty in 1(0). In addition, there is no simple expression for the uncertainty in the differential cross section. Because of these problems only a small number of comparisons of differential cross sections for different potential energy surfaces have been made. 

Fig. 2. Reactive differential cross section for the LEPS potential based upon 10,026 reactive trajectories. The uncertainties were estimated from equations (7) and (8) as follows the uncertainty shown in the top part is 6f and that shown in the bottom part is 6f/sin 9 or 51, whichever is smaller.

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