24.What is the product of the following reaction? 0 H2NNH2,KOH Heat a.3-methylpentane b.3-methyl-2-pentanol c.3-methyl-2-pentene d.3-methyl-1-pentyne 25.What is the product of the following reaction? HgC CH3 Cold,dilute KMnO4. OH a.CH:CH=O b.meso-2,3-butanediol c.racemic(2R.3R)and(2S.3S)-2.3-butanediol .Wht istere 代互变异构) a.resonance forms b.stereoisomers c.constitutional isomers d.different conformations of the same compound Section III Reactions and Synthesis (41 points in all) SCORE. Reactions Draw the major product for each of the following reactions;you should assume that "excess reagents"are present,if appropriate.Show product regiochemistry and stereochemistry where appropriate (for 27-31,2 points each.For 32-36,3points each,25 points). 1.Cl2.FeCl3 →( 2201 0 2.Zn(Hg),HCI OH PCC 28 CH2Cl2 (注：Pyridinium chlorochromate,氯铬酸吡啶盐) ) 29 NH NaBrOO( 31 席4页共6页第 4 页 共 6 页 24. What is the product of the following reaction? O H2NNH2, KOH Heat a. 3-methylpentane b. 3-methyl-2-pentanol c. 3-methyl-2-pentene d. 3-methyl-1-pentyne 25. What is the product of the following reaction? CH3 H H H3C Cold, dilute KMnO4, OH - a. CH3CH=O b. meso-2,3-butanediol c. racemic (2R,3R) and (2S,3S)-2,3-butanediol d. cis-2,3-epoxybutane 26. What is the relationship between keto and enol tautomers(酮式和醇式互变异构)? a. resonance forms b. stereoisomers c. constitutional isomers d. different conformations of the same compound Section III Reactions and Synthesis（41 points in all） SCORE Reactions Draw the major product for each of the following reactions; you should assume that "excess reagents" are present, if appropriate. Show product regiochemistry and stereochemistry where appropriate (for 27-31,2 points each. For 32-36, 3points each，25 points). 27. 1. Cl2, FeCl3 O O ( ) 2. Zn(Hg), HCl 28 OH PCC CH2Cl2 (注：Pyridinium chlorochromate, 氯铬酸吡啶盐) 29 （ ） OH O HO O 30. O2N CH3 H2O 95 oC KMnO4 31. NaBrO/OH￾NH ( ) 2 O