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CARBOXYLIC ACIDS Properties and Synthesis NOMENCLATURE.

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Presentation on theme: "CARBOXYLIC ACIDS Properties and Synthesis NOMENCLATURE."— Presentation transcript:

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2 CARBOXYLIC ACIDS Properties and Synthesis

3 NOMENCLATURE

4 -oic acid IUPAC ending -carboxylic acid IUPAC ending for ring compounds IUPAC NOMENCLATURE

5 3-Methylbutanoic acid  -Methylbutyric acid Isovaleric acid 2-Chloropentanoic acid  -Chlorovaleric acid Naming

6 2-Methylpropanoic acid  -Methylpropionic acid Isobutyric acid 4-Aminobutanoic Acid  -Aminobutyric Acid “GABA” Naming

7 Benzoic acid Benzenecarboxylic acid Cyclohexanecarboxylic acid More Naming

8 Common Names

9 Formula Common Name SourceIUPAC Name Melting Point Boiling Point HCO 2 Hformic acidants (L. formica) methanoic acid 8.4 ºC101 ºC CH 3 CO 2 Hacetic acidvinegar (L. acetum)ethanoic acid16.6 ºC118 ºC CH 3 CH 2 CO 2 Hpropionic acid milk (Gk. protus prion) propanoic acid-20.8 ºC141 ºC CH 3 (CH 2 ) 2 CO 2 Hbutyric acidbutter (L. butyrum)butanoic acid-5.5 ºC164 ºC CH 3 (CH 2 ) 3 CO 2 Hvaleric acidvalerian rootpentanoic acid-34.5 ºC186 ºC CH 3 (CH 2 ) 4 CO 2 Hcaproic acidgoats (L. caper)hexanoic acid-4.0 ºC205 ºC CH 3 (CH 2 ) 5 CO 2 Henanthic acidvines (Gk. oenanthe)heptanoic acid-7.5 ºC223 ºC CH 3 (CH 2 ) 6 CO 2 Hcaprylic acidgoats (L. caper)octanoic acid16.3 ºC239 ºC CH 3 (CH 2 ) 7 CO 2 Hpelargonic acidpelargonium (an herb)nonanoic acid12.0 ºC253 ºC CH 3 (CH 2 ) 8 CO 2 Hcapric acidgoats (L. caper)decanoic acid31.0 ºC219 ºC

10 SYNTHESIS OF SYNTHESIS OF CARBOXYLIC ACIDS

11 Oxidation of Primary Alcohols with KMnO 4 with KMnO 4 two  -hydrogens + MnO 2 precipitate

12 Oxidation of Primary Alcohols with K 2 Cr 2 O 7 with K 2 Cr 2 O 7

13 Oxidation of Side Chains Example KMnO 4 

14 Carbonation of Grignard Reagents ( or Alkyllithium Compounds ) ( R-Li )

15 Formation of Nitriles and Hydrolysis DMSO H 2 SO 4 H2OH2O heat SN2SN2

16 or CO 2 CrO 3 H 2 SO 4 KMnO 4 H 2 SO 4 KMnO 4 NaCN acetone DIBAL or Rosenmund KMnO 4 Li or Mg H2OH2O H2OH2O H 2 SO 4 H2OH2O or KMnO 4 SYNTHESIS OF CARBOXYLIC ACIDS ( DUE TO LACK OF SPACE REACTION CONDITIONS ARE ABBREVIATED) KMnO 4 ( benzene = R sidechain = R’ ) This is all stuff you know! SOCl 2 Chap 19

17 Physical Properties of Carboxylic Acids

18 Physical Properties of Some Organic Compounds FormulaIUPAC Name Molecular Weight Boiling Point Water Solubility CH 3 (CH 2 ) 2 CO 2 Hbutanoic acid88164 ºCvery soluble CH 3 (CH 2 ) 4 OH1-pentanol88138 ºCslightly soluble CH 3 (CH 2 ) 3 CHOpentanal86103 ºCslightly soluble CH 3 CO 2 C 2 H 5 ethyl ethanoate8877 ºCmoderately soluble

19 CH 3 CH 2 CO 2 CH 3 methyl propanoate8880 ºC slightly soluble CH 3 (CH 2 ) 2 CONH 2 butanamide87216 ºCsoluble CH 3 CON(CH 3 ) 2 N,N- dimethylethanamide ºCvery soluble CH 3 (CH 2 ) 4 NH 2 1-aminobutane87103 ºCvery soluble CH 3 (CH 2 ) 3 CNpentanenitrile83140 ºC slightly soluble CH 3 (CH 2 ) 4 CH 3 hexane8669 ºCinsoluble

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21 ACIDITY

22 Carboxylate Ion Formation They are acids, ya know ! pK a   5 carboxylate ioncarboxylic acid

23 + +.. : : H 2 SO 4.. : + Protonation and Deprotonation of a Carboxylic Acid.. : NaOH.. : - equivalent structures due to resonance

24 Electron-withdrawing Groups: –strengthen acids –weaken bases Electron-releasing Groups: –weaken acids –strengthen bases

25 Substituents with Electron-Withdrawing Resonance ( - R ) Effects -R substituents strengthen acids and weaken bases X Y

26 +R substituents weaken acids and strengthen bases Substituents with Electron-Releasing Resonance ( + R ) Effects hydroxy mercapto methyl amino fluoro bromo alkoxy acyloxy dialkylamino alkyl chloro iodo Y..

27 Substituents with Electron-Withdrawing ( - I ) Inductive Effects ( - I ) Inductive Effects -I substituents strengthen acids and weaken bases carboxyl alkoxycarbonyl acyl hydroxyl mercapto amino chloro nitro cyano sulfonic acid alkoxy dialkylamino trimethylammonium fluoro bromo iodo X

28 Substituents with Electron-Releasing Inductive ( + I ) Effects +I substituents weaken acids and strengthen bases methyl alkyl oxide carboxylate R

29 increasing acidity

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31 Benzoic Acid: pK a = 4.19 ortho meta para ortho meta para

32 Benzoic Acid: pK a =

33 Benzoic Acid: pK a = 4.19

34 Acidity of Carboxylic Acids CompoundpK a CompoundpK a HCO 2 H3.75CH 3 CH 2 CH 2 CO 2 H4.82 CH 3 CO 2 H4.74ClCH 2 CH 2 CH 2 CO 2 H4.53 FCH 2 CO 2 H2.65CH 3 CHClCH 2 CO 2 H4.05 ClCH 2 CO 2 H2.85CH 3 CH 2 CHClCO 2 H2.89 BrCH 2 CO 2 H2.90C 6 H 5 CO 2 H4.20 ICH 2 CO 2 H3.10p-O 2 NC 6 H 4 CO 2 H3.45 Cl 3 CCO 2 H0.77p-CH 3 OC 6 H 4 CO 2 H4.45

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36 Reactions of Carboxylic Acids Nucleophiles that are also strong bases react with carboxylic acids by removing a proton first, before any nucleophilic substitution reaction can take place.

37 Nucleophilic acyl substitution reactions of carboxylic acids

38 Treatment of a carboxylic acid with thionyl chloride (SOCl 2 ) affords an acid chloride. This is possible because thionyl chloride converts the OH group of the acid into a better leaving group, and because it provides the nucleophile (Cl ¯ ) to displace the leaving group.

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40 Although carboxylic acids cannot readily be converted into anhydrides, dicarboxylic acids can be converted to cyclic anhydrides by heating to high temperatures. This is a dehydration reaction because a water molecule is lost from the diacid.

41 ESTERIFIKASI ASAM KARBOKSILAT

42 Esterification of a carboxylic acid occurs in the presence of acid but not in the presence of base. Base removes a proton from the carboxylic acid, forming the carboxylate anion, which does not react with an electron-rich nucleophile.

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44 Intramolecular esterification of  - and  -hydroxyl carboxylic acids forms five- and six-membered lactones.

45 Carboxylic acids cannot be converted into amides by reaction with NH 3 or an amine because amines are bases, and undergo an acid-base reaction to form an ammonium salt before nucleophilic substitution occurs. However, heating the ammonium salt at high temperature (>100°C) dehydrates the resulting ammonium salt of the carboxylate anion to form an amide, although the yield can be low.

46 The overall conversion of RCOOH to RCONH 2 requires two steps: [1] Acid-base reaction of RCOOH with NH 3 to form an ammonium salt. [2] Dehydration at high temperature (>100°C).

47 A carboxylic acid and an amine readily react to form an amide in the presence of an additional reagent, dicyclohexylcarbodimide (DCC), which is converted to the by-product dicyclohexylurea in the course of the reaction.

48 DCC is a dehydrating agent. The dicyclohexylurea by-product is formed by adding the elements of H 2 O to DCC. DCC promotes amide formation by converting the carboxy group OH group into a better leaving group.

49 Carboxylic Acid Derivatives

50 Related Carbonyl Derivatives

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