CARBOXYLIC ACIDS Since the carboxyl group is polar, carboxylic acids contain dipole-dipole forces, London forces and are able to hydrogen bond. Therefore carboxylic acids will have high melting and boiling points and will be soluble in water. Contain the carboxyl functional group

NAMING CARBOXYLIC ACIDS 1.Identify the longest chain containing the carboxyl group, remove the “e” and add “oic acid”.

Naming Carboxylic Acids Any substituents are numbered using the lowest sum. The carboxyl carbon is always C-1 on a chain, so no locator number is needed. Carboxylic acids rank over aldehydes, ketones, alcohols, alkenes and alkynes

Examples: propanoic acid benzoic acid 2-ethylhexanoic acidpent-3-enoic acid

5-oxo-2-propylhexanoic acid 2-(3-hydroxypropyl)hexanedioic acid

Multiple Carboxyl Groups When naming multiple carboxyl groups, the suffix –dioic acid is used for acids with a carboxyl group at each end of the parent chain. Note that the full alkyl name is used (the ‘e’ is not dropped)

Examples: propanedioic acid 2-ethyl-5-methylhexanedioic acid

Ring Structures Keep the “e” and add suffix “carboxylic acid”. cyclohexanecarboxylic acid cyclohexanedicarboxylic acid

Expanded Molecular Formulas Carboxyl group is represented by COOH HOOCCH 2 CH 2 CH 2 CH 3

COMMON ORGANIC ACIDS

Making Carboxylic Acids: An Oxidation Reaction

What is an ester? Made from an alcohol and a carboxylic acid.

Making an Ester carboxylic acid + alcohol ester + water H 2 SO 4 

NAMING An ester has two parts – the part that comes from the alcohol and the part that comes from the carboxylic acid Convert the suffix “(a)nol” ending of the alcohol to ‘yl’ Convert the ‘oic acid’ ending of the carboxylic acid to “oate” i.e. “alkyl oate” Note the space between the alkyl and oate names CH 2 CH 3 C O H 3 C O methyl propanoate alcohol Carboxylic acid

Side Chains on the Alcohol Side The carbon atoms that are attached to an oxygen atom are assigned as C-1 (this means that you are numbering atoms from the middle of the molecule) H H C H 3 C 3 C O C O H 3 C methylethyl ethanoate (isopropyl ethanoate) If there is a side chain attached to the alcohol part, then the side chain names are attached to the ‘akyl’ part of the ester name 1 2

Side Chains on the Acid Side It there are side chains attached to the carboxylic acid part, then the side chain names are attached to the ‘oate’ part of the ester name H H C C C O C O H 3 H C H C 3 3 ethyl 2-methylpropanoate

Side Chains Everywhere! H H C C C O C O H 3 H C H C 3 3 H C 3 H C methylethyl 2-methylbutanoate

More Reactions of Esters Hydrolysis (breaking down an ester)

Waxes Waxes are mixtures of esters having carbon chains in the range of 16 to 34 carbons on each side of the ester linkage. Since the hydrocarbon chains are so long, waxes are very water repellant. Biological Importance: fruit, leaves, insects

Fats and Oils Fats and oils are triesters of glycerol that contain at least one fatty acid. Fatty acids are carboxylic acids that contain carbons and having varying degrees of unsaturation glycerol + 1 fatty acid --> monoglyceride + water glycerol + 2 fatty acids --> diglyceride + water glycerol + 3 fatty acids --> triglyceride + water

Salicylates Contain salicylic acid. Most common is acetyl salicyclic acid “ASA” (AKA aspirin) which is used for pain relief and as an antiseptic.

Odours of Selected Esters Esters occur naturally in many plants and are responsible for the odours of fruits and flowers. Synthetic esters are often added as flavourings to processed foods, and as scents to cosmetics and perfumes.