Tosylate—Another Good Leaving Group

We have now learned two methods to convert the OH group of an alcohol to a better leaving group treatment with strong acids (Section 9.8), and conversion to an alkyl halide (Sections 9.11-9.12). Alcohols can also be converted to alkyl tosylates. 

Recall from Section 1.4B that a third-row element like sulfur can have 10 or 12 electrons around it in a valid Lewis structure. 

An alkyl tosylate is often called simply a tosylate. 

An alkyl tosylate is composed of two parts the alkyl group R, derived from an alcohol and the tosylate (short for p-toluenesulfonate), which is a good leaving group. A tosyl group, CH3C6H4SO2-, is abbreviated as Ts, so an alkyl tosylate becomes ROTs. 

Problem 9.29 Draw the products of each reaction, and indicate the stereochemistry at any stereogenic centers. 

organic chemists try to devise several different ways to perform the same overall reaction. For now, though, concentrate on one or two of the most general methods, so you can better understand the underlying concepts. 

Why are there so many ways to convert an alcohol to an alkyl halide Alkyl halides are versatile starting materials in organic synthesis, as shown in Sample Problem 9.5. 

Problem 9.27 Draw two steps to convert (CH3)2CHOH into each of the following compounds (CH3)2CHN3 and (CH3)2CHC)CH2CH3. 

---