16.35Recall that p-toluenesulfonate (tosylate) is a good leaving group in nucleophilic substitution reac-tions. The nucleophile that displaces tosylate from carbon is the alkoxide ion derived from the hy-droxyl group within the molecule. The product is a cyclic ether, and the nature of the union of thetwo rings is that they are spirocyclic.16.36(a)Because all the peaks in the 1H NMR spectrum of this ether are singlets, none of the protonscan be vicinal to any other nonequivalent proton. The only C5H12O ether that satisfes this re-quirement is tert-butyl methyl ether.(b)A doublet–septet pattern is characteristic of an isopropyl group. Two isomeric C5H12O etherscontain an isopropyl group: ethyl isopropyl ether and isobutyl methyl ether.The signal of the methine proton in isobutyl methyl ether will be split into more than a septet,however, because in addition to being split by two methyl groups, it is coupled to the two pro-tons in the methylene group. Thus, isobutyl methyl ether does not have the correct splitting
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