2. Consider the first four mechanisms we proposed for the acid catalyzed hydrolysis of an acetal to the hemiacetal and one equivalent of alcohol at the end of the first lecture notes set to answer the following questions. H3O+ +ROH (a) When isotopically labeled water/acid is used (H2O18,H3O+18), if the labeled oxygen is found in the hemiacetal OH group which mechanism/mechanisms can be eliminated? (b) When isotopically labeled water/acid is used (H2O18,H3O+18), if the labeled oxygen is found in the alcohol ROH, which mechanism/mechanisms can be eliminated? (c) When isotopically labeled acetal 18OR is used, what position/positions in the products would the labelled oxygen atom end up when: (i) mechanism A is operating? (i) mechanism B is operating? (i) mechanism C is operating? (i) mechanism D is operating? (d) If chiral R groups are used on the acetal (OR*), which mechanisms are supported when the stereochemistry of the R group in the alcohol is: (i) retained? (ii) inverted? (iii) racemized