544 CARBOXYLIC ACID DERIVATIVES: NUCLEOPHILIC ACYL SUB Step 5: Dissociation of protonated form of tetrahedral intermediat This step yields ethyl alcohol and the protonated form of benzoic acid C6HSC-OCH,CH3 CHSC HOCH2 CH3 OH :OH H Protonated form Ethyl alcohol Step 6: Deprotonation of protonated form of benzoic acid H O H CaH CN CsSC H Benzoic acid Hydronium benzoic acid 20.11 To determine which oxygen of 4-butanolide becomes labeled withO, trace the path ofO-labeled water(0=O)as it undergoes nucleophilic addition to the carbonyl group to form the tetrahedral H,e sO-labeled The tetrahedral intermediate can revert to unlabeled 4-butanolide by loss of O-labeled water Alternatively it can lose ordinary water to give O-labeled lactone 8o-jJabeled Water The carbonyl oxygen is the one that is isotopically labeled in theO-enriched 4-butanolide. 20.12 On the basis of trimyristin's molecular formula CasHs,Os and of the fact that its hydrolysis gives only glycerol and tetradecanoic acid CH(CH)12 CO, H, it must have the structure shown CHa(CH2)n2CO OC(CH,)I2CH OC(CH)12CH3 (CasH86O6) Back Forward Main Menu TOC Study Guide Toc Student OLC MHHE WebsiteStep 5: Dissociation of protonated form of tetrahedral intermediate This step yields ethyl alcohol and the protonated form of benzoic acid. Step 6: Deprotonation of protonated form of benzoic acid 20.11 To determine which oxygen of 4-butanolide becomes labeled with 18O, trace the path of 18O-labeled water as it undergoes nucleophilic addition to the carbonyl group to form the tetrahedral intermediate. The tetrahedral intermediate can revert to unlabeled 4-butanolide by loss of 18O-labeled water. Alternatively it can lose ordinary water to give 18O-labeled lactone. The carbonyl oxygen is the one that is isotopically labeled in the 18O-enriched 4-butanolide. 20.12 On the basis of trimyristin’s molecular formula C45H86O6 and of the fact that its hydrolysis gives only glycerol and tetradecanoic acid CH3(CH2)12CO2H, it must have the structure shown. CH3(CH2)12CO OC(CH2)12CH3 OC(CH2)12CH3 O O O Trimyristin (C45H86O6) H OH O OH Tetrahedral intermediate O O 18O-labeled 4-butanolide H2O Water 4-Butanolide O O 18O-labeled water H2O H Tetrahedral intermediate O OH OH (O  18O) Benzoic acid C6H5C OH O Water O H H Hydronium ion H O H H Protonated form of benzoic acid C6H5C OH O H Oxonium ion C6H5C OCH2CH3 OH OH H Protonated form of benzoic acid C6H5C OH OH Ethyl alcohol HOCH2CH3 544 CARBOXYLIC ACID DERIVATIVES: NUCLEOPHILIC ACYL SUBSTITUTION Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website