Relationship Between Structure And Properties Of Oxygen Containing Organic Compounds

Carboxylic acid derivatives are a class of organic compounds that are derived from carboxylic acids through the replacement or modification of one of the functional groups in the carboxyl group. As we know, carboxyl group in carboxylic acids consists of a carbonyl group and a hydroxyl group attached to the same carbon atom. Carboxylic acid derivatives can be formed by replacing the hydroxyl group with another functional group while retaining the carbonyl group. The most common types of carboxylic acid derivatives include esters, amides, acid halides and acid anhydride.

Esters are formed by replacing the hydroxyl group of a carboxylic acid with an alkyl group or aryl group. They have the general formula R-COOR. R represents alkyl group or aryl group. Do you know how juices get their fruity odor? This is due to esters. Esters are responsible for the fruity and floral smell found in many natural products. Some examples of esters are ethyl acetate and methyl benzoate.

Esters can be prepared by reacting carboxylic acids with alcohol. For example, ethyl acetate can be synthesized by the reaction of acetic acid with ethanol. Sulfuric acid is used as a catalyst in this reaction. The smell of esters can vary. It depends on the type of carboxylic acid and alcohol used to prepare ester.

Esters can undergo hydrolysis in the presence of water or a strong acid or base. Hydrolysis is the breakdown of a molecule with help of water. Acidic hydrolysis involves the reaction of an ester with water in the presence of an acid catalyst. Carboxylic acid and alcohol are formed as products. For example, hydrolysis of ethyl acetate with dilute sulfuric acid yields acetic acid and ethanol.

Transesterification is a reaction in which the alkyl group or aryl group of an ester is exchanged with another alcohol. This reaction is commonly catalyzed by an acid or base. For example, ethyl acetate can undergo transesterification with methanol in the presence of sodium methoxide as a base catalyst to form methyl acetate and ethanol.

Amides are formed by replacing the hydroxyl group of a carboxylic acid with an amine group. They have the general structure RCONH₂. R can be an alkyl group or aryl group. Acetamide is an example of amide.

The formation of an amide involves the reaction of a carboxylic acid with ammonia. This reaction can be catalyzed by acid or base. For example, acetamide can be synthesized by the reaction of acetic acid with ammonia.

Amides can undergo hydrolysis in the presence of water or an acid or base. Acidic hydrolysis of amides involves the reaction of amide with water in the presence of an acid catalyst. This results in the formation of a carboxylic acid and an amine. For instance, acetamide can be hydrolyzed with hydrochloric acid to yield acetic acid and ammonia.

Amides can be reduced to primary amines using reducing agents such as lithium aluminum hydride or sodium borohydride. The carbonyl group in the amide is converted to a methylene group. -CH₂ group is called methylene group. Amine is formed as product. For example, acetamide can be reduced to ethylamine using lithium aluminum hydride.

Acid halides are formed by replacing the hydroxyl group of a carboxylic acid with a halogen atom. They have the general structure RCOX. R represents alkyl group or aryl group X represents halogen atom. Acetyl chloride is an example of acid halide.

Acid halides undergo nucleophilic acyl substitution reactions with nucleophiles such as alcohols, amines, or water. When acid halides react with alcohol the acyl group substitutes the hydrogen atom of the alcohol. This results in the formation of an ester. For example, acetyl chloride reacts with methanol to produce methyl acetate.

Reaction of acid halide with ammonia results in the formation of an amide. For example, acid halide reacts with ammonia to form acetamide. Acid halides can also react with water to form carboxylic acid. For example, the reaction of acetyl chloride with water results in the formation of ethanoic acid.

Acid halides can also be reduced to aldehydes or primary alcohols using reducing agents such as lithium aluminum hydride. The carbonyl group in the acid halide is reduced to an alcohol group. For example, acetyl chloride can be reduced to acetaldehyde.

Acid anhydrides are formed by removing a water molecule from two carboxylic acid molecules. They have the general formula (RCO)₂O. R represents an alkyl group or aryl group. Acetic anhydride is an example of acid anhydrides.

Acid anhydrides can be hydrolyzed in the presence of water or an acid or base. The reaction of acid anhydride with water results in the formation of two carboxylic acids. For instance, hydrolyzing acetic anhydride with water produces two molecules of acetic acid.