Amines correlation table

Variation of the pKa of the amine enabled us to show that the process occurred via path A since intermediate 8 was clearly visible in all reactions and conversion to product 10 correlated with the pKas of the primary amines 11 and the secondary amines 8 (Table 2, Figs. 4a and b). 

The correlation tables for amines and amine salts are in Appendix 2, Table A2.7. 

The left-hand side of Equation 2.15 refers to a ratio of experimental rate constants kQ K and ksoiv are obtained entirely from kinetic data (Equation 2.12) and the ratio k0 K/k0 v is the rate enhancement for a particular concentration of amine for example, if the ratio is 2.0, addition of the amine has doubled the rate, corresponding to a rate enhancement of 100%. The right-hand side refers to the observed product ratio, which is obtained by independent measurements (e.g. by HPLC). A fit to Equation 2.15, as observed for m-nitroaniline in methanol at 25°C, exemplifies a rate-product correlation (Table 2.4) [44]. From the agreement between calculated and observed yields of amide shown in Table 2.4, we conclude that there are indeed competing second-order reactions, as assumed in Scheme 2.21. If the mechanism proceeded via an intermediate formed in a slow step, which was trapped by the amine in a subsequent rapid step, then more amide product would be formed than predicted by Equation 2.15. 

Interestingly, comparison of the values of pAHB and the acidity constants pKa in a series of the same family of compounds, such as carbonyl compounds, amines, pyridines and sulphoxides, shows that a good correlation exists between p/CHB and pgiving straight lines in each series of compounds with parallel slopes. This enables one to calculate the difference of the several pKa values at the same p/CHB value, and vice versa. Thus, at p= 0, p/CHB values of various functional groups were determined and are shown in Table 13. 

Data given in Tables 1-6 clearly show a significant dependence of P2 and p4 on amine concentration, that is, at least one of the apparent rate constants kj contains a concentration factor. Thus, according to the mathematical considerations outlined in the Analysis of Data Paragraph, both p2, P4 exponents and the derived variables -(P2 + p)4> P2 P4 ind Z (see Eqns. 8-12) are the combinations of the apparent rate constants (kj). To characterize these dependences, derived variables -(p2+p)4, P2 P4 and Z (Eqns. 8,11 and 12) were correlated with the amine concentration using a non-linear regression program to find the best fit. Computation resulted in a linear dependence for -(p2 + p)4 and Z, that is... 

Table 2 shows a strong correlation between the p7fa s of amines 11 and 8 with the most basic 11a proceeding to 98% conversion to product over 48 h at rt (Table 2, entry 1) and the least basic Table 2 (entries 5 and 6) exhibiting very low conversion to product. 

Table 2 Correlation of conversion to isoindolone with pA"a primary 11 and secondary 8 amines...

A recent study of the reactions of 2,4-dinitrochlorobenzene and of picryl chloride with a series of nucleophiles that are presented in Table 6 shows that a plot (not shown) of log k against the pK values of all the nucleophiles is badly scattered77. Differences of up to 108 are observed for bases with similar pKa values. Part of this scatter is due to deviations that result because different families of nucleophiles (with different nucleophilic atoms) give rise to different Br0nsted correlation lines. Thus, for the reactions of picryl chloride good correlations are observed for a family of oxyanions (ft = 0.38, plot not shown), primary and secondary amines (Figure 4, ft = 0.52) and quinuclidines (Figure 4, P = 0.66). 

In the first DNMR studies of push-pull ethylenes, a strong effect of solvent polarity on the C=C barriers was noted. Thus Kende et al. (64) found AG = 18.0 kcal/mol for 46a in N,/V-dimethylformamide (dielectric constant e = 38) and 19.4 kcal/mol in Ph20 ( = 4). Similar observations have been made by many other workers, and they have been seen as a strong support for a zwitterionic transition state. Kessler et al. (140) observed reasonably linear correlations between AG for two ketene aminals and the solvent polarity parameter T (141) with variations in AG of ca. 2.5 kcal/mol over T values between 25 and 46. Similarly, Shvo et al. (78) found linear correlations between log km and the polarity parameter Z (141) for three compounds from Table 12. 

---