1. 54c) Fill in the blanks. 12 3

2. f) 1 2 3

5. j) 12 34

6. k) 12 3 4 5

7. 55d) 12 3 4

8. f) 12 3 4 5

9. j) 1 2 3 4

10. k) 12 3 4 5

11. Oxidation and Reduction Alcohols are oxidized to a variety of carbonyl compounds. Oxidation of Alcohols

12. Oxidation and Reduction Recall that the oxidation of alcohols to carbonyl compounds is typically carried out with Cr 6 + oxidants, which are reduced to Cr 3 + products. CrO 3, Na 2 Cr 2 O 7, and K 2 Cr 2 O 7 are strong, nonselective oxidants used in aqueous acid (H 2 SO 4 + H 2 O). PCC is soluble in CH 2 Cl 2 (dichloromethane) and can be used without strong acid present, making it a more selective, milder oxidant. Oxidation of Alcohols

13. Oxidation and Reduction Any of the Cr 6+ oxidants effectively oxidize 2° alcohols to ketones. Oxidation of 2 ° Alcohols

14. Oxidation and Reduction 1° Alcohols are oxidized to either aldehydes or carboxylic acids, depending on the reagent. Oxidation of 1 ° Alcohols

15. Oxidation and Reduction Oxidation of 1 ° Alcohols

16. 58a)1 2 3 4 5

17. Alkyl Halides and Elimination Reactions A single elimination reaction produces a  bond of an alkene. Two consecutive elimination reactions produce two  bonds of an alkyne. E2 Reactions and Alkyne Synthesis

18. Alkyl Halides and Elimination Reactions Two elimination reactions are needed to remove two moles of HX from a dihalide substrate. Two different starting materials can be used—a vicinal dihalide or a geminal dihalide. E2 Reactions and Alkyne Synthesis

19. Alkyl Halides and Elimination Reactions Stronger bases are needed to synthesize alkynes by dehydrohalogenation than are needed to synthesize alkenes. The typical base used is ¯ NH 2 (amide), used as the sodium salt of NaNH 2. KOC(CH 3 ) 3 can also be used with DMSO as solvent. E2 Reactions and Alkyne Synthesis

20. Alkyl Halides and Elimination Reactions The reason that stronger bases are needed for this dehydrohalogenation is that the transition state for the second elimination reaction includes partial cleavage of the C—H bond. In this case however, the carbon atom is sp 2 hybridized and sp 2 hybridized C—H bonds are stronger than sp 3 hybridized C—H bonds. As a result, a stronger base is needed to cleave this bond. E2 Reactions and Alkyne Synthesis

21. Alkyl Halides and Elimination Reactions E2 Reactions and Alkyne Synthesis Figure 8.9 Example of dehydrohalogenation of dihalides to afford alkynes

22. b) 12

23. Alkynes Because sp hybridized C—H bonds are more acidic than sp 2 and sp 3 hybridized C—H bonds, terminal alkynes are readily deprotonated with strong base in a Br Ø nsted- Lowry acid-base reaction. The resulting ion is called the acetylide ion. Introduction to Alkyne Reactions—Acetylide anions

24. Alkynes Reactions of Acetylide Anions Acetylide anions react with unhindered alkyl halides to yield products of nucleophilic substitution. Because acetylides are strong nucleophiles, the mechanism of substitution is S N 2, and thus the reaction is fastest with CH 3 X and 1 0 alkyl halides.

25. Alkynes Reactions of Acetylide Anions Steric hindrance around the leaving group causes 2° and 3 ° alkyl halides to undergo elimination by an E2 mechanism, as shown with 2-bromo-2-methylpropane. Thus, nucleophilic substitution with acetylide anions forms new carbon-carbon bonds in high yield only with unhindered CH 3 X and 1 ° alkyl halides.

26. Alkynes Reactions of Acetylide Anions Acetylide anions are strong nucleophiles that open epoxide rings by an S N 2 mechanism. Backside attack occurs at the less substituted end of the epoxide.

27. h) 12 3 4 56