2-propyl tosylate, solvolysis

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

Rates are thus expected to show the first-order dependence on the concentration ofT added, and the rate enhancement (RE, Equation 9.8) for a given concentration of T is easily shown to be the corresponding product ratio [Q] / [P ]. Behaviour of this kind occurs, for example, in the solvolysis of2-propyl tosylate in aqueous ethanol [22]. Products are those of nucleophilic substitution - a mixture of 2-propanol and 2-propyl ethyl ether. When the reaction is rim in the presence of sodium azide, an excellent nucleophile, rates of disappearance of the tosylate are enhanced and 2-propyl azide is also formed. The relationships between amounts of azide product and rate enhancements for a series of different azide concentrations were accurately described by Equations 9.5-9.8. 

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 ... 

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

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... 

The nitrous acid deamination appears to be as complex as the nitrosoamide reaction, and in a common solvent it appears that similar mechanisms are followed. For example, the nitrosonaphthamide of 1-phenylethylamine in acetic acid, and the reaction of 1-phenyl-ethylamine with nitrous acid in the same solvent yield 1-phenylethyl naphthoate (Table 7) and 1-phenylethanol respectively, both with 79-81% retention of configuration. These products are the intramolecular products from the respective reactions, and thte stereochemical results suggest that they are formed by a common path. Similar results were also found in the deaminations of S-cholC stanylamine 2-phenyl-2-butylamine ° and 1,2,2-triphenylethyl amine Also pertinent, is the finding that the acetates fi-om the deamination of n-propylamine in acetic acid, by the two methods, contained similar amounts of the isomeric product, isopropyl acetate the amount of isomerization observed was far greater than in the solvolysis of n-propyl tosylate in the same solvent... 

The nitrous acid deamination of n-propylamine in acetic acid yields an acetate fraction containing far more isopropyl acetate (32%) than the acetate from the solvolysis of n-propyl tosylate in the same solvent (2-8%) Also, the deamination of n-butylamine in acetic acid yields a butanol fraction containing 35% of 2-butanol, whereas the solvolysis of n-butyl -nitrobenzenesulfonate in the same solvent was reported to give exclusively n-butyl acetate . These results are reasonable in terms of the larger positive charge on the cation formed in deamination, relative to the charge on the more solvated ion formed in solvolysis. 

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