Bransted plot

The data in Table 5 were used (Miles et al., 1966) to construct a Bransted plot of the variation of the rate coefficient for proton removal with acidity along the series of substituted malonate monoanions the plot is reproduced in Fig. 12. The value of the gradient of the best line (a = ca 0.5) was interpreted (Miles et al., 1966) as indicating that proton removal by hydroxide ion occurs in a single step through a transition state in which the... 

The Bransted plots for the (La3 + ( OCH3))2 and 9 Zn2 + ( OCH3)-catalyzed methanolyses of 20 and 21 shown in Figs 7 and 8 exhibit gradients that are much steeper than the corresponding Bra ns ted plots for the methoxide reactions. This is easily visualized in the log/log plot of the second-order rate constants of the metal-catalyzed reactions vs. the methoxide reaction which is shown in Fig. 12 where the gradient of the La3+ plot is 1.94 + 0.10 while that for the 9 Zn2+( OMe) plot is 1.49 + 0.11. The situation for the phosphorothioates is not nearly so pronounced since the similar plots for series 21 (not shown) has a gradient for the La3+ plot of 1.15 + 0.10 while that for the 9 Zn2 + ( OMe) plot is 0.99 0.06.17c... 

General-base catalysis was also detected in this reaction and attributed to general-acid catalysis of breakdown of the monoanion (18). The Bransted P-value was 0.57 and so the a-value for expulsion of the alcohol from the ionized form is 0.43. The point for the water-catalysed reaction lies on the Bransted plot for catalysis by other bases which supports the view that these reactions proceed by similar mechanisms as formulated in (17) and (18). 6... 

Fig 3 Bransted plot for water-promoted a-proton abstraction for a series of protonated acetophenones [411 (Dubois et ai, 1981)... 

Figure 3. Bransted-type plots for aminolysis in 1 M KC1 at 25 °C 0,2-nitrophenyl acetate , 3-chlorobenzoic acid 0,2,6-dinitrobenzoic acid.

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