Carboxylic Acids and Their Derivatives

1. Carboxylic Acids and Their Derivatives

2. CARBOXYLIC ACIDS • CONTENTS • Structure of carboxylic acids • Nomenclature • Physical properties of carboxylic acids • Preparation of carboxylic acids • Reactions of carboxylic acids • Derivatives of carboxylic acids: • a. Acid chlorides • b. Esters • c. Amides • d. Anhydrides • Occurrence and uses of carboxylic acids and their derivatives

3. STRUCTURE OF CARBOXYLIC ACIDS • Carboxylic acids are organic acids contain one or more carboxyl group • A carboxyl group is made up of a carbonyl (C=O) group • and a hydroxyl (O-H) group • It is often written in condensed form as –CO2H or –COOH • The general formula of a carboxylic acid is R-COOH or • Ar-COOH

4. NOMENCLATURE Of CARBOXYLIC ACIDS • IUPAC Nomenclature of carboxylic acids • Find the longest continuous carbon chain contains the COOH group to get the name of the parent hydrocarbon, the ending -e is replaced by the suffix –oic acid. • Number the chain starting with the carbon of COOH group as C-1 • If there are substituents identify their names and positions and list them as prefixes in alphabetical order. • Examples: (CH3)2CH - CH(CH3) - CH2 - CH2 - COOH is called • 4,5-Dimethylhexanoic acid

5. Cyclic compounds (Aliphatic or aromatic) containing one or more COOH groups attached to the ring are named by identifying the name of the ring followed by the word carboxylic acid or dicarboxylic acids etc. The carbon atom bearing the carboxylic group is numbered 1 and the substituents are numbered relative to it.

6. Common nomenclature of carboxylic acids • Some carboxylic acids are called after characteristic properties or their origin. • Formula IUPAC name Common name origin of name • HCOOH methanoic acid formic acid Latin for ant • CH3COOH ethanoic acid acetic acid Latin for vinegar • CH3CH2COOH propanoic acid propionic acid Greek for milk • CH3 (CH2)2COOH butanoic acid butyric acid Latin for butter • CH3 (CH2)3COOH pentanoicaicvaleric acid valerian root • The positions of the carbons present on the acid chain, are located by the Greek letters α indicating the carbon atom next to COOH group (C2), β (C3), γ (C4), δ (C5), etc .

7. common: -- Dimethyl butyric acid IUPAC: 2,3-Dimethyl butanoic acid • Some aromatic acids have common names.

8. PHYSICAL PROPERTIES OF CARBOXYLIC ACIDS Solubility • Carboxylic acids are polar, they can form hydrogen bonds with water molecules • Smaller carboxylic acids (1 to 4 carbons) are soluble with water • Whereas the solubility of bigger carboxylic acids decrease with size due to the increasing hydrophobic nature of the alkyl chain. • Aromatic acids are insoluble in water

9. Boiling Points • Carboxylic acids have exceptionally high boiling points than alcohols of identical relative molecular masses, For example: M.F. M.W bp / °C 1- Propanol C3H8O 60.01 97.2 Ethanoic acid C2H4O2 60.05 118 • This is due to carboxylic acids usually exist as dimeric pairs by forming two intramolecular hydrogen bonds in nonpolar media

10. Acidity and acid strength • Carboxylic acids are the most acidic simple organic compounds (they are stronger acids by over ten powers of ten compared to alcohols of comparable weights); also they are more acidic than phenols • However, they are weak acids compared to inorganic acids (HCl or H2SO4) • Adjacent electron withdrawing substituentsnearthe carboxyl group increase the acidity • Whereas electron releasing substituentsdecrease the acidity . • HCOOH>CH3COOH>CH3CH2COOH>CH3CH2CH2CH2COOH ( size of R group) • Cl3CCOOH>Cl2CHCOOH>ClCH2COOH>CH3COOH>(OCH3)CH2COOH • ( number of e.w.g. and e.r. g.) • CH3CH2CH2CH(Cl)COOH>CH3CH2CH(Cl)CH2COOH>CH3CH(Cl)CH2CH2COOH>CH2(Cl)CH2CH2CH2COOH ( position of e.w.g. relative to COOH group)

11. Preparation of Carboxylic acids 1- Oxidation of primary alcohols or aldehydes 2- Oxidation of Alkylbenzenes

12. 3- Carbonation of Grignard Reagents 4- Hydrolysis of nitriles

13. Reactions of Carboxylic Acids 1- Salts Formation

14. 2- Substitution of hydroxyl group

15. Carboxylic Acid Derivatives Acid Chloride Ester Amide acid anhydride • 1-Nomenclature of acid chloride • Replace the -ic acid ending in the name of the parent acid • by –yl chloride IUPAC: Ethanoyl chloride Benzoylchloride Common : Acetyl chloride

16. Reactions of Acid Chlorides

17. Reactions of Esters

18. Reactions of Amides

19. Reactions of Acid anhydride

20. Occurrence and Uses of Carboxylic Acids and their Derivatives • Carboxylic acids and their derivatives are widespread in nature

21. Carboxylic acids are used in the production of polymers, pharmaceuticals, solvents, and food additives.Examples

22. PABA Antibiotic ‘’ Magic bullet’’ • Sulfanilamide It eliminates bacteria that cause infections by stopping the production of folic acid inside the bacterial cells • Para-amino benzoic acid, more commonly known as PABA, is a non-protein amino acid widely available in nature. It can be found in food sources such as liver, eggs (whole), molasses, rice, wheat germ and spinach. PABA is often referred to as Vitamin Bx (part of the Vitamin B complex family) and it has been suggested to contribute to a lot of processes in the body and it marketed as PABA vitamin.. • Most Popular Use of PABA: PABA is widely used as a topical sunscreen (i.e. Sunscreen with PABA), as it has the ability to absorb UV rays from the sun ; it is considered as antioxidant, it has been found to reduce wrinkles and even to restore gray hair to its original color, further more play a role in red cells formation and manufacturing of folic acid, may play a role in reducing fatigue and limiting the effects of depression.