Carboxylic Acids

A carboxylic acid contains a carboxyl group, which is a carbonyl group attach to a hydroxyl group. carbonyl group O  CH 3 — C—OH hydroxyl group or CH 3 COOH carboxyl group Carboxylic Acids CH 3 CO 2 H

The common names use prefixes “form-” and “acet-” for the first two carboxylic acids. H-COOH methanoic acid formic acid CH 3 -COOH ethanoic acid acetic acid CH 3 -CH 2 -COOH propanoic acid CH 3 -CH 2 -CH 2 -COOH butanoic acid Naming Carboxylic Acids

–Identify the root. Name the parent alkane. Drop the –e on the parent alkane to get the root. –Identify the suffix. For carboxylic acid, the suffix is –oic acid. No numbers in the suffix because the carboxyl group is always carbon 1. –Identify the prefix. Name and number any alkyl side groups on the main chain. –Name the compound. Combine the prefix, root, and suffix Methylbutanoic acid OH OOH Hydroxylhexanoic acid CH 3 ─CH 2 ─CH─COOH CH 2 – CH 3 2-Ethylbutanoic acid 2 CH 3 ─CH─CH 2 ─COOH CH 3 1

Draw 2-ethylpentanoic aicd

Physical properties of Carboxylic Acids 1- The carboxyl group contains three polar covalent bonds; C=O, C-O, and O-H. So they are so polar. 2- Carboxylic acids have higher boiling points than other types of organic compounds (with the same molecular weight) because of hydrogen bonding. 3- They are more soluble in water than alcohols, ethers, aldehydes, and ketones because of stronger hydrogen bonding. 4- Liquid carboxylic acids have sharp and disagreeable odors. 5- They taste sour (exist in pickle, lime, and lemon). H 3 C C O O H CH 3 C O O H  -  +  +  - Hydrogen bonding between two molecules

Esters

Formation of Esters RCOH O A carboxylic acid = Fischer Esterification RCOR ' O RC-OH O H - O R ' = = An alcohol A carboxylic acid An ester H 2 SO 4 + H 2 O

Naming Esters 1. Identify the root. Identify part of ester that contains carbonly group (from acid). Name the parent carboxylic acid. Drop the suffix of the of the acid to form the root 2.Identify the suffix. The suffix for an ester is – oate 3.Consider the part of the ester that is associated with the alcohol. Name only the alkyl group. 4. Name the compound. Combine the prefix, root and suffix.

acid alcohol  methyl CH 3 — C—O —CH 3 ethanoate IUPAC: methyl ethanoate Naming of Esters O

propyl CH 3 — C—O —CH 2 —CH 2 —CH 3 Propyl ethanoate (IUPAC) CH 3 —CH 2 —C—O—CH 2 —CH 3 Ethyl propanoate Naming of Esters O O

Name the following ester Parent carboxylic acid is 3-methylbutanoic acid Root: 3-methylbutan Suffix: -oat Alcohol: ethanol Prefix:ethyl Name: ethyl 3-methylbutanoate

Draw butyl propanoate Alcohol: butanol Acid: propanoic acid

Esters give flowers and fruits their pleasant fragrances and flavors. Properties of Esters Hydrolysis: reaction with water. (breaking a bond and adding the elements of water) RCOR' O RC-OH O H - O R ' = = An alcohol A carboxylic acid An ester + H 2 O + Heat Acid

Chemical properties of Carboxylic Acids 3- Fischer Esterification: - A carboxylic acid reacts with an alcohols to form an ester. - Using an acid catalyst such as concentrated sulfuric acid. The best way to prepare an ester.