Reactivity comparison

Some results obtained by the HMO method (one of the more useful for reactivities comparisons) are summarized in Tables III-17 and III-18. 

Deng B, Stone A (1996) Surface-catalyzed chromium(VI) reduction reactivity comparisons of different... 

The reactivity of 1,8-naphthyridine (27) is greater than expected.61,79 Here, unlike the diazines, the two heteroatoms with their unshared electron pairs are in separate rings. After correction for the two kinetically equivalent reactive sites, the rate constant for 27 is nearly the same as that for pyridine and four times larger than that for quinoline. These results are surprising, especially when it is remembered that the diaza substrate is substantially less basic than the comparison compounds. Correcting for the diminished nucleophilicity expected to be associated with the lower basicity of 27 serves to make the reactivity comparisons even more striking.61... 

It can be concluded that significant differences in metal-carbon bond distances to coordinated olefins are not reflected in either the slip parameter or the barrier to rotation of the indenyl ring in this series of complexes. However, the relative strengths of the interactions between the [Rh( /5-indenyl)] fragment and OFCOT and COT are illustrated by some reactivity comparisons in Section VIII,F,2. 

An interesting reactivity comparison was carried out with l-(l-methyl-2-indolyl)-l-(jV-methyl-2 -pyrrolyl)ethene 57 obtained via the corresponding carbinol. An inspection of its structure suggests that the molecule could react in a cycloaddition reaction as a vinylindole or as a 2-vinylpyrrole. In reactions with dienophiles, which include DMAD, it reacted as a 2-vinylindole, affording a carbazole derivative 58 (89JHC1869). 

Figure 13 Reactivity comparisons of peroxo-dicopper(II) complexes 3, 8, and 15.

The notion of an electrophilic attack mediated by the peroxo group in [Cu2(R-XYL-H)(02)]2+ (7) is also in accord with studies on reactivity comparisons of three classes of peroxo-dicopper(II) complexes, including [ (TMPA)Cu 2(02)]2+ (3) and [Cu2(Nn)(02)]2+ (5, n = 4) (Figure 5) (48). We found that the ii-rfirf-022 ) group in [Cu2(N4)(02)]2+ (5) behaves as a nonbasic or electrophilic peroxo ligand, in contrast to the basic or nucleophilic behavior of the peroxo group in 3, which possesses end-on coordination. For example, in reactions with H+, C02, and PPh3,... 

Figure 5. Summary of reactivity comparisons of end-on vs. side-on bound peroxo-dicopper(II) complexes (48,).

A Mo —N Reactivity comparison between ring and isomeric nitride complex 20040M3126... 

Because of the deactivated ir-deficient nature of the ring, nucleophilic attack can readily occur on tetrazoles. Nucleophilic replacement of halogens at the C-5 position has been widely used for the synthesis of disubstituted tetrazoles, e.g. (56). Kinetic studies of the reaction between 5-bromo-l-methyltetrazole and the 2-methyl isomer with piperidine have shown the 1-methyl compound to be considerably more reactive. Comparison of these kinetics with similar reactions for a series of azoles has suggested that two to three deactivating doubly bound nitrogens (—N=) are required to overcome the electron release from one pyrrole-type nitrogen atom in these systems <67JCS(B)64l>. 

The reactions of furansulfonyl chlorides with anilines (entry 11)123 in MeOH yield a linear Bronsted plot with fix =0.51, which indicates an Sw2 mechanism rather than a stepwise process. This value is quite similar to those found for the reactions of anilines with benzenesulfonyl chloride (0.63)117, with 2-thiophenesulfonyl chloride (0.53)124 and with 3-thiophenesulfonyl chloride (0.54)125. Thus their anilinolysis mechanism is also expected to be S/y2. The reaction rate therefore depends not only on the nucleophile basicity but also on the substrate reactivity. Comparison of the reaction rates leads to the following reactivity order for the Ar moiety benzene > 3-thiophene > 3-furan > 2-furan > 2-thiophene. This reactivity sequence follows the order of the resonance interaction between the... 

Table II Cross Reactivity Comparison for Various Analytes on Different Antisera/Coating Antigen Systems (NI refers to non inhibition of ELISA system by that analyte)...

Reactivity Comparison Between Various Classes Table of Examples Classification Process Reactivity Table... 

Scheme 29 Reactivity comparison of Pd-NHC complexes 27 and 29 in the Negishi coupling...

Later the same authors61 published a study on the reactivities of a number of electrogenerated radical cations toward St and isobutyl vinyl ether (IBVE). The reactivity comparison was made among 9-phenylanthracene (9PA), 9,10-dimethyl-anthracene (DMA), 9,10-diphenylanthracene (DPA), 1,3,6,8-tetraphenylpyrene (TPP), rubrene (RU), triphenylene (TP), perylene (p). The stability of the ion radicals, in the absence of the monomers, is in the order ... 

Strucmre-reactivity comparisons of the reactions of thioalkyl carbene complexes with those of the alkoxy analogs reveal interesting differences as well as similarities. Table 17 provides a comparison of rate and equilibrium constants between the reactions of n-PrS with 97 and 11 or 13. The following points are noteworthy. 

---