16_ - P1: QZI/SRB P2: xxx Printer: Hamilton JWDD052-16...

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P1: QZI/SRB P2: xxx Printer: Hamilton JWDD052-16 JWDD052-Solomons-v3 April 30, 2007 11:9 16 ALDEHYDES AND KETONES I. NUCLEOPHILIC ADDITION TO THE CARBONYL GROUP SOLUTIONS TO PROBLEMS 16.1 3-Methyl-2-butanone O 2,2-Dimethylpropanal 2-Pentanone 3-Pentanone O H O O Pentanal 2-Methylbutanal 3-Methylbutanal O H O H O H CH 3 O H 3-Methylbenzaldehyde ( m -tolualdehyde) CH 3 H 4-Methylbenzaldehyde ( p -tolualdehyde) O H O CH 3 H 2-Methylbenzaldehyde ( o -tolualdehyde) Acetophenone (methyl phenyl ketone) Phenylethanal (phenylacetaldehyde) (a) (b) 314
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P1: QZI/SRB P2: xxx Printer: Hamilton JWDD052-16 JWDD052-Solomons-v3 April 30, 2007 11:9 ALDEHYDESANDKETONESI.NUCLEOPHILICADDITIONTOTHECARBONYLGROUP 315 16.2 (a) 1-Pentanol, because its molecules form hydrogen bonds to each other. (b) 2-Pentanol, because its molecules form hydrogen bonds to each other. (c) Pentanal, because its molecules are more polar. (d) 2-Phenylethanol, because its molecules form hydrogen bonds to each other. (e) Benzyl alcohol because its molecules form hydrogen bonds to each other. 16.3 CH 2 Cl 2 PCC CH 3 CH 2 CH O CH 3 CH 2 CH 2 OH (a) (1) LiAlH[OC(CH 3 ) 3 ] 3 (2) H 2 O Et 2 O, 78 ° C CH 3 CH 2 CO 2 H CH 3 CH 2 CH O CH 3 CH 2 CCl SOCl 2 O (b) 16.4 Br 2 Fe Mg Et 2 O Br MgBr (1) (2) H 3 O + O H H PCC CH 2 Cl 2 H O OH (a) (b) (c) (d) (1) KMnO 4 , OH , heat (2) H 3 O + SOCl 2 CH 3 OH O (1) LiAlH[OC(CH 3 ) 3 ] 3 Et 2 O, 78 ° C Cl O O H (2) H 2 O H 2 CrO 4 acetone O OH CH 3 COCl AlCl 3 O
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P1: QZI/SRB P2: xxx Printer: Hamilton JWDD052-16 JWDD052-Solomons-v3 April 30, 2007 11:9 316 ALDEHYDESANDKETONESI.NUCLEOPHILICADDITIONTOTHECARBONYLGROUP CN H 3 O + Br CN NMgBr MgBr diethyl ether O (e) (f ) (1) i -Bu 2 AlH, hexane, 78 ° C (2) H 3 O + CN C 6 H 5 O O C 6 H 5 (1) i -Bu 2 AlH, hexane, 78 ° C (2) H 3 O + H O OCH 3 (g) H 16.5 (a) The nucleophile is the negatively charged carbon of the Grignard reagent acting as a carbanion. (b) The magnesium portion of the Grignard reagent acts as a Lewis acid and accepts an electron pair of the carbonyl oxygen. This acid-base interaction makes the carbonyl carbon even more positive and, therefore, even more susceptible to nucleophilic attack. O C Mg R X C R O MgX δ + δ + δ δ (c) The product that forms initially (above) is a magnesium derivative of an alcohol. (d) On addition of water, the organic product that forms is an alcohol. 16.6 The nucleophile is a hydride ion. 16.7 O + C H H H H C H H H O H O O + C H H OH OH 16.8 Acid-Catalyzed Reaction O 18 OH + OH + HA A HA A + H 2 18 O H 2 18 O + H 2 18 O H 2 O + H 2 O OH 18 OH OH 18 OH + OH 2 HA A HA A 18 O
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P1: QZI/SRB P2: xxx Printer: Hamilton JWDD052-16 JWDD052-Solomons-v3 April 30, 2007 11:9 ALDEHYDESANDKETONESI.NUCLEOPHILICADDITIONTOTHECARBONYLGROUP 317 O OH H 2 18 O 18 OH H 2 O + + 18 OH + 18 OH O 18 OH OH H 2 O OH Base-Catalyzed Reaction OH H 2 O 18 O OH OH + OH 18 O 16.9 HO CH 2 OH O HOCH 2 Acetal group O HO O OH CH 2 OH HO OH HO CH 2 OH O HOCH 2 Acetal group O HO O OH CH 2 OH HO OH Sucrose Sucrose 16.10 H H OH + HA A HA A H 2 O + H 2 O + HO CH 3 HO CH 3 OC H 3 H + H OH HA A O CH 3 H (hemiacetal) CH 3 H OH 2 O H CH 3 O + + H + HO CH 3 HO CH 3 HA A + CH 3 O CH 3 H H
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16_ - P1: QZI/SRB P2: xxx Printer: Hamilton JWDD052-16...

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