ALDEHYDES AND KETONES: NUCLEOPHILIC ADDITION TO THE CARBONYL GROUP 431 Step 4: CH,CH CHACH CdHC—9cH2CH3+:O I CH COCH, CH3+ H Hemiacetal Step 5: CH,CH3 CHCH CHCH C6HSCH--OCH, CH3 H CHCH-O C6HSCH CHCH + O: H CH, CH3 CHCH+ C6HSCH H- 17.10 The conversion requires reduction; however, the conditions necessary (LiAlH,) would also reduc the ketone carbonyl. The ketone functionality is therefore protected as the cyclic acetal HOCH, CH, OH CHC COH o-C COH Reduction of the carboxylic acid may now be carried out O 1. LiAlH, COH CHOH C Hydrolysis to remove the protecting group completes the synthesis CH, H2O,HCI CHOH Back Forward Main Menu TOC Study Guide Toc Student OLC MHHE WebsiteStep 4: Step 5: Step 6: Step 7: 17.10 The conversion requires reduction; however, the conditions necessary (LiAlH4) would also reduce the ketone carbonyl. The ketone functionality is therefore protected as the cyclic acetal. Reduction of the carboxylic acid may now be carried out. Hydrolysis to remove the protecting group completes the synthesis. CH2OH CH3C CH2OH O H2O, HCl 4-Acetylbenzyl alcohol O O C H3C COH O CH2OH 1. LiAlH4 2. H2O O O C H3C O O C H3C 4-Acetylbenzoic acid COH O CH3C O HOCH2CH2OH p-toluenesulfonic acid, benzene COH O O O C H3C O H CH2CH3 O H CH2CH3 C6H5CH O C6H5CH O H H O H CH2CH3 O H CH2CH3 C6H5CH O C6H5CH OH H O H CH2CH3 H O H CH2CH3 O H CH2CH3 OCH2CH3 C6H5CH HO C6H5CH OH O H CH2CH3 H O H CH2CH3 C6H5C OCH2CH3 O H H H C6H5C OCH2CH3 H HO Hemiacetal ALDEHYDES AND KETONES: NUCLEOPHILIC ADDITION TO THE CARBONYL GROUP 431 Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website