Chapter 14 Carboxylic Acid Derivatives: Nucleophilic Acyl Substitution - PowerPoint PPT Presentation

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Chapter 14 Carboxylic Acid Derivatives: Nucleophilic Acyl Substitution

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Chapter 14 Carboxylic Acid Derivatives: Nucleophilic Acyl Substitution
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Chapter 14 Carboxylic Acid Derivatives: Nucleophilic Acyl Substitution

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  1. Chapter 14 Carboxylic Acid Derivatives: Nucleophilic Acyl Substitution 14.1 Carboxylic Acid Derivatives and Nomenclature 14.2 Structure of carboxylic acid derivatives 14.3 Preparation of carboxylic acid derivatives 14.4 Nucleophilic substitution at the acyl carbon 14.4.1 Hydrolysis 14.4.2 Reactions with alcohols 14.4.3 Reactions with amines

  2. 14. 5 Reduction 14.5.1 Reduction by LiAlH4 (LAH) and its derivatives 14.5.2 Reduction by Na 14.5.3 Reaction with Grignard reagents 14.6 Reactions of amides 14.6.1 Dehydration of amides 14.6.2 The Hofmann Rearrangement 14.7 Spectroscopic analysis of carboxylic acid derivatives

  3. 14.1 Carboxylic Acid Derivatives and Nomenclatures Acyl halides 酰卤 Propanoyl chloride Propanoicacid Propanoyl chloride 丙酰氯 P309, 10.1 Carboxylic acid anhydrides 酸 酐 Acetic anhydride Acetic acid Acetic anhydride 乙酸酐 Esters 酯 Ethyl acetate Aceticacid Ethyl benzoate (苯甲酸乙酯) Benzoicacid Ethyl acetate 乙酸乙酯

  4. Acetamide 乙 酰胺 Benzonitrile 苄腈 Phenyl cyanide 苯基氰 Amides 酰胺 N-Methylbenzamide N- 甲基苯甲 酰胺 Nitrile 腈 Aceticacid Acetamide Benzonitrile Benzoicacid N,N-Dimethylform- amide (DMF) N, N- 二甲基甲 酰胺 4-Methylpentanenitrile 4-甲基戊腈

  5. O L R A common feature of carboxylic acid derivatives: Hydrolysis to carboxylic acids 14.2 Structure of carboxylic acid derivatives p - π Conjugation +C Effect:

  6. 14.3 Preparation of Carboxylic Acid Derivatives 14.3.1 Preparation of Acyl Halides SOCl2(Thionyl chloride) PBr3(Phosphorous tribromide) 14.3.2 Preparation of Acid Anhydride

  7. 14.3.3 Preparation of Esters 14.3.4 Preparation of Amides

  8. 14.4 Nucleophilic substitution at the acyl carbon P318,10.5 14.4.1 Hydrolysis Ch.P390

  9. Acid anhydrides Esters Amides Hydrolysis of Catalyzed by a acid or a base. Mechanism: Hydrolysis of Acyl halides is catalyzed by a base. Saponification(皂 化 反应) Base-promoted hydrolysis of ester Step 1 Nucleophilic addition of hydroxide ion to carbonyl group. P331

  10. Step 2 Elimination of leaving group to restore carbonyl group: Step 3 Proton transfer to yield alcohol and carboxylate ion:

  11. Reactivity of carboxylic acid derivatives: Hydrolysis of Nitriles: P320 14.4.2 Reactions with alcohols Acyl halides Acid anhydrides Esters Nitriles Alcohols or phenols Esters

  12. Benzoyl chloride Ethyl benzoate (80%) Asprin (阿司匹林) Salicylic acid (水杨酸) Alcohols (Exchange of esters) Esters Esters

  13. Methyl acrylate (丙烯酸甲酯) Butyl alcohol (丁醇) Butyl acrylate (丙烯酸丁酯) (94%) Alcoholysis of Nitriles: Ch.P391

  14. N-Benzoyl- Piperidine (N-苯甲酰哌啶) (87-91%) Benzoyl chloride Piperidine (哌啶) Floroacetamide (氟乙酸酰胺) (90%) Ethyl Floroacetate (氟乙酸乙酯) Acyl halides Carboxylic acid anhydrides Esters 14.4.3 Reactions with amines Ammonia or amines Amides

  15. 14. 5 Reduction 14.5.1 Reduction by LiAlH4 (LAH) and its derivatives

  16. Amides Nitriles LiAlH4 Amines Acryl halides Carboxylic acid Acid anhydrides Esters Primary alcohols LiAlH4 1) LiAlH(OR)3 Acyl halides Amides Aldehydes 2) H2O

  17. 14.4.2 Reduction by Na Ch. P393 Bouveault - Blanc reduction Ethanol Butanol Pentanol Esters Na reflux Primary alcohols Ethyl oleate 油酸乙酯 Oleic alcohol 油醇 The unique method for the preparation of unsaturated primary alcohols in industry

  18. Tertiary alcohols RMgX Carboxylic acid derivatives RMgX Ketones 14.5.3 Reaction with Grignard reagents 1 mol RMgX Low temperature

  19. Hydrolysis 1. RMgX Imine 亚胺 Nitriles Ketones 2. H2O Reactions of nitriles with Grignard reagents Addition RLi reacts in the same way and are often used instead of RMgX

  20. 14.6 Reactions of amides 14.6.1 The dehydration of amides Dehydrating agents: P4O10 (P2O5), (脱水剂)(CH3CO)2O Amides Heating To form nitrils 2-Methylpropanamide 2-甲基丙酰胺 2-Methylpropanenitrile 2-甲基丙腈 (69-86%)

  21. 14.6.2 The Hofmann Rearrangement (Hofmann 降解反应) Ch.P396, (丙) N-unsubstituted amides Br2 / OH- Carbonyl group had been plucked out to form primary amines having one less carbon atom than amide Mechanism: Step 1 Formation of an N-bromo amide intermediate: Amide nitrogen anion as a nucleophile Deprotonation of amide

  22. Step 2 Rearrangement of the N-bromo amide to an isocyanate(异氰酸酯) Deprotonation of N-bromo amide, the group R migrates from C atom to N atom to form an isocyanate. Step 3 Hydrolysis of isocyanate by base- catalyzed Carbamic acid (异氰酸)dissociates to an amine and CO2

  23. The features of Hofmann rearrangement: • N-unsubstituted amides as substrates • 2. Rearrangement proceeds with retention • of configuration at migrating group (S)-1-Phenyl-2-propanamine (S)-2-Methyl- 3-Phenylpropanamide

  24. Stretching frequency of C=O (cm-1) Compounds 1815~1785 1850~1800 and 1780~1740 1735 1680~1630 RCOCl (RCO)2ORCO2R RCONH2 : The stretching frequency of : 2210~2260 cm-1 14. 7 Spectroscopic analysis of carboxylic acid derivatives IR: Table 1. The stretching frequency of C=O

  25. Stretching frequency of C-O: 1310 ~1050 cm-1 Esters Carboxylic acid anhydrides Amides: Stretching frequency of N – H bond: 3500 ~3200 cm-1

  26. 1H NMR: 13C NMR: α - H δ: 2 ~ 3 ppm δ: 120 ppm Amide: N - H δ: 5 ~8 ppm

  27. Problems to chapter 14 P 346 10.31 (a),(d),(e) 10.32(c)~(g) 10.33(b),(d),(g) 10.37 10.39 10.41 10.42 (a),(c) 10.45 10.46(a), (c) 10.47 10.55 10.56(b) 10.57 10.58 10.59 10.60 10.61 10.62