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Dolbier HW Solutions 318 - 412 ETHERS EPOXIDES AND SULFIDES...

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16.29 The proper approach to this problem is to fi rst write the equations in full stereochemical detail. ( a ) It now becomes clear that the arrangement of groups around the stereogenic center remains un- changed in going from starting materials to products. Therefore, choose conditions such that the nu- cleophile attacks the CH 2 group of the epoxide rather than the stereogenic center. Base-catalyzed hydrolysis is required; aqueous sodium hydroxide is appropriate. The nucleophile (hydroxide ion) attacks the less hindered carbon of the epoxide ring. ( b ) Inversion of con fi guration at the stereogenic center is required. The nucleophile must therefore at- tack the stereogenic center, and acid-catalyzed hydrolysis should be chosen. Dilute sulfuric acid would be satisfactory. The nucleophile (a water molecule) attacks that carbon atom of the ring that can better support a positive charge. Carbocation character develops at the transition state and is better supported by the carbon atom that is more highly substituted. 16.30 The key intermediate in the preparation of bis(2-chloroethyl) ether from ethylene is 2-chloroethanol,
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