2-propyl tosylate

Table 5.22. Extent of Solvolysis with Aryl Participation as a Function of Substituent and Solvent for l-Aryl-2-propyl Tosylates...

Figure 17. Correlation of solvolytic rate constants at 25° for 2-propyl tosylate and Y (data from Bentley and Schleyer, 1976, and Leffek et al., 1960). Log [kEW/kAeOH] = B-A.

Figure 20. Correlation of solvolysis rate constants at 25° for 2-propyl tosylate and yOTs or (0 4Noxs + 0-58YoTs)- (From Schadt et al., 1976, and reproduced with permission of the American Chemical Society.)...

We have studied three data sets for the solvolysis of l-(3 - or 4 -substituted phenyl)-2-propyl tosylates We have used the MYT equation in the form ... 

Fig. 10. Taft treatment of the acetolysis of secondary alkyl and l-aryl-2-propyl tosylates. [Lancelot, C. J., Cram, D. Y., Schleyer, P. v. R., in Carbonium ions. Olah,...

Table 12. Rate-product correlation for the solvolysis of l-phenyl-2-propyl tosylate (345)...

Steric Effects on Solvent Nucleophilicity. The N0Ts values (Table III) show that TFA is, by this measure, less nucleophilic than HFIP. As the rate ratios 2-AdOTs (CH3)2CHOTs in TFA and 97% HFIP were very similar, we initially proposed (17) that solvolyses of (CH3)2CHOTs in these two weakly nucleophilic solvents were kc processes. More detailed studies (4, 50) later showed that solvolyses of secondary tosylates in 100% HFIP were closer to limiting (kc) than those in TFA. This apparent reverse of the order of nucleophilicity could be caused by steric effects (50), which could also contribute to the lower precision of the iN/mY equation (5) in correlations of rate data for secondary substrates for example, for 2-propyl tosylate, solvolyses in TFE and HFIP are predicted to be slower than observed, whereas reaction in CF3C02H is predicted to be faster than observed (3). 

It is known that for SnI ewaction (substitution-nucleophilic-unimolecular) [140-141] a key intermediate is a carbocation, therefore the more reactive substrate will be the one that can produce the most stable carbocation. The reactivity of methyl, ethyl, 2-propyl, and 2-methyl-2-propyl tosylates under SnI reaction conditions is inversely proportional to the calculated hydride affinity of the corresponding carbocations. The calculated values were in agreement with the experimental findings which were obtained through solvolysis rate measurement of these tosylates under SnI conditions [142, 143]. Correlation of the cation stability-hydride and affinity-solvolytic rate of the reaction under Sn 1 reaction conditions was observed for the allyl cation (allyl, 3-penten-2-yl, and 2-methyl-3-butene-2-yl cations)[144] and the benzyl cation (benzyl, 1-phenylethyl, and 2-phenyl-2-propyl cations) [145] series. The most reactive substrates were the ones that formed the carbocations with the lowest hydride affinity. 

Extent of solvolysis with aryl participation as a function of substituent and solvent for l-aryl-2-propyl tosylates... 

Methyl-4(5)-nitroimidazole added to a soln. of Na in methanol, evaporated to dryness, and the resulting Na-salt refluxed 2 hrs. in a mixture of isopropyl iodide and dimethylformamide -> 12 g. l-isopropyl-2-methyl-4-nitroimidazole. - The 5-nitro isomer was obtained by refluxing the above startg. m. with 2-propyl tosylate in benzene. M. Hoffer et al., J. Med. Chem. 14, 993 (1971). 

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