1. Carboxylic Acids & Derivatives Dr. Michael P. Gillespie

2. Introduction Carboxylic acids contain a carboxyl group (- COOH). The name carboxyl is derived from terms carbonyl and hydroxyl, the two structural units that make up the carboxyl group. Dr. Michael P. Gillespie2

3. Carboxylic Acids: Structure & Properties Carboxylix acids are characterized by the carboxyl group. The carboxyl group consists of two very polar functional groups, the carbonyl group and the hydroxyl group. Carboxylic acids are therefore very polar compounds. They can hydrogen bond to one another and to water. Dr. Michael P. Gillespie3

4. Carboxylic Acids: Structure & Properties Consequently, they are soluble in water and boil at higher temperatures. As the carbon content increases, the solubility decreases because the carboxylic acids become more hydrocarbonlike. Dr. Michael P. Gillespie4

5. Carboxyl Group Dr. Michael P. Gillespie5

6. Some Important Carboxylic Acids Methanoic (formic) acid causes the burning sensation of ant bites. Ethanoic (acetic) acid provides the zip to vinegars. Polymers of lactic acid are used as biodegradable sutures and biodegradable plastic bags (potato peels are a great source of this lactic acid). Dr. Michael P. Gillespie6

7. Some Important Carboxylic Acids Butanoic (butyric) acid is the odor associated with rancid butter. When these carboxylic acids react with alcohols they produce esters, which contribute to the fragrance and flavor of many fruits. Octanoic (caprylic) acid contributes to hunger sensations. Citric acid provides sharp taste to foods, is a food preservative, and an antioxidant. Dr. Michael P. Gillespie7

8. Some Important Carboxylic Acids Lactic acid provides a tangy flavor. Oxalic acid is found in spinach and rhubarb and contributes to the formation of kidney stones. Benzoic acid is a preservative in soft drinks, pickles, jellies, etc. Salicylic acid is a disinfectant. Dr. Michael P. Gillespie8

9. Some Important Carboxylic Acids Acetylsalicylic acid is aspirin. Hippocrates identified a bitter extract from willow bark that reduced fevers and relieved pain. Dr. Michael P. Gillespie9

10. Biodegradable Plastic Polymers of lactic acid make sheets of plastic. Polylactic acid (PLA) is produced by the fermentation of sugars. Bacteria in soil can readily break down PLA. When french fries are produced, nearly half of the potato is wasted (approximately 10 billion pounds of potato waste each year). This potato waste can be used to make PLA. Dr. Michael P. Gillespie10

11. Preparation of Carboxylic Acids Carboxylic acids are prepared by the oxidation of aldehydes and primary alcohols. The primary alcohol is oxidized into an aldehyde, which is further oxidized into a carboxylic acid. Dr. Michael P. Gillespie11

12. Acid-Base Reactions When strong bases are added to a carboxylic acid neutralization occurs. This produces a carboxylic acid salt and water. Dr. Michael P. Gillespie12

13. Esterification Carboxylic acids react with alcohols to form esters and water. Dr. Michael P. Gillespie13

14. Esters: Structure & Properties Esters are mildly polar and have pleasant aromas. Their boiling points and melting points are comparable to those of aldehydes and ketones. Dr. Michael P. Gillespie14

15. Preparation of Esthers Esters are formed from the reaction between a carboxylic acid and an alcohol. Dr. Michael P. Gillespie15

16. Hydrolysis of Esthers An ester can undergo hydrolysis to revert back to the parent carboxylic acid and alcohol. Saponification is the base catalyzed hydrolysis of an esther. Soaps are made by this process. Dr. Michael P. Gillespie16

17. Acid Chlorides Acid chlorides are noxious chemicals formed in the reaction of a carboxylic acid and reagants such as PCl 3 or SOCl 2. Dr. Michael P. Gillespie17

18. Acid Anhydrides Acid anhydrides are formed by the combination of an acid chloride and a carboxylate anion. Acid anhydrides can react with an alcohol to produce an ester and a carboxylic acid. Dr. Michael P. Gillespie18

19. Chemistry of Flavor & Fragrance Carboxylic acids are often foul smelling. Butyric acid produces the smell of rancid butter. When carboxylic acids are converted to esters they produce pleasant smells. Dr. Michael P. Gillespie19

20. Phosphoesters An alcohol can react with phosphoric acid to produce a phosphate ester (phosphoester). When two phosphate groups are joined, the resulting bond is a phosphoanhydride bond. These two functional groups are important to the structure and function of adenosine triphosphate (ATP), the universal energy currency of all cells. Dr. Michael P. Gillespie20

21. Thioesters Thioesters are produced by the reaction between a thiol and a carboxylic acid. This reaction is catalyzed by cellular enzymes. This reaction helps with fatty acid metabolism. Coenzyme A is the most important thiol in these reactions. Dr. Michael P. Gillespie21