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Carboxylic Acids & Derivative s Dr. Michael P. Gillespie

Carboxylic Acids & Derivatives

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Carboxylic Acids & Derivatives. Dr. Michael P. Gillespie. 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. Carboxylic Acids: Structure & Properties. - PowerPoint PPT Presentation

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Page 1: Carboxylic Acids & Derivatives

Carboxylic Acids &

DerivativesDr. Michael P. Gillespie

Page 2: Carboxylic Acids & Derivatives

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. Gillespie 2

Page 3: Carboxylic Acids & Derivatives

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. Gillespie 3

Page 4: Carboxylic Acids & Derivatives

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. Gillespie 4

Page 5: Carboxylic Acids & Derivatives

Carboxyl Group

Dr. Michael P. Gillespie 5

Page 6: Carboxylic Acids & Derivatives

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. Gillespie 6

Page 7: Carboxylic Acids & Derivatives

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. Gillespie 7

Page 8: Carboxylic Acids & Derivatives

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. Gillespie 8

Page 9: Carboxylic Acids & Derivatives

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. Gillespie 9

Page 10: Carboxylic Acids & Derivatives

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. Gillespie 10

Page 11: Carboxylic Acids & Derivatives

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. Gillespie 11

Page 12: Carboxylic Acids & Derivatives

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. Gillespie 12

Page 13: Carboxylic Acids & Derivatives

Esterification• Carboxylic acids react with alcohols to

form esters and water.

Dr. Michael P. Gillespie 13

Page 14: Carboxylic Acids & Derivatives

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. Gillespie 14

Page 15: Carboxylic Acids & Derivatives

Preparation of Esthers

• Esters are formed from the reaction between a carboxylic acid and an alcohol.

Dr. Michael P. Gillespie 15

Page 16: Carboxylic Acids & Derivatives

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. Gillespie 16

Page 17: Carboxylic Acids & Derivatives

Acid Chlorides• Acid chlorides are noxious chemicals

formed in the reaction of a carboxylic acid and reagants such as PCl3 or SOCl2.

Dr. Michael P. Gillespie 17

Page 18: Carboxylic Acids & Derivatives

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. Gillespie 18

Page 19: Carboxylic Acids & Derivatives

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. Gillespie 19

Page 20: Carboxylic Acids & Derivatives

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. Gillespie 20

Page 21: Carboxylic Acids & Derivatives

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. Gillespie 21