Thinking Mechanistically About Alkynes

The preparation and properties of alkynes extend some topics explored in earlier chapters  

The greater character of sp hybrid orbitals compared with sp and sp gives alkynes certain properties beyond those seen in alkanes and alkenes. It is convenient to think of. yp-hybridized carbon as more electronegative than its sp or sp counterparts. 

Problems 9.38-9.42 emphasize mechanistic reasoning. By thinking mechanistically you reduce the need to memorize facts while increasing your ability to analyze and understand new material. Nucleophilic addition to alkynes, for example, is not covered in this chapter but is the focus of problem 9.42, which can be solved by thinking mechanistically. 

38 Which of the following best describes what happens in the first step in the mechanism of the reaction shown  

39 Which of the following best describes what happens in 

CH3CH2CH2—CHBr CH3CH2CH2—CHBr CH3CH2CH—CBr CH3CH2CH- CHBr 

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