228 of the textbook hydrolysis needs more vigorous

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Unformatted text preview: acetal. Why were the other acetals (one is a thio- acetal) not affected by this treatment? How would you hydrolyse them? Chloroform (CHCl3) is the solvent. MeO S CF3CO2H H2O S O MeO O CHCl3 0°C 1 hour OHC S S O O Purpose of the problem Revision of the different types of acetal and their relative reactivity. Suggested solution Cyclic acetals are more stable than non- cyclic ones as we explain on p. 228 of the textbook. Hydrolysis needs more vigorous conditions. Thioacetals are much harder to hydrolyse because sulfides are even less basic than ethers. They can be hydrolysed using electrophiles that attack sulfur readily, such as Hg(II) or methylating agents. This is one possible solution: OHC S TsOH H2O S O O heat OHC S S CHO Hg(OAc)2 AcOH, H2O O OHC CHO Solutions for Chapter 11 ...
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This document was uploaded on 02/10/2014.

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