Investigate The Relationship Between Structure And Properties Of Nitrogen Containing Organic Compounds

We already know that aliphatic amines are more basic than alcohols. But do you know aliphatic amines are also more basic than aniline. Aniline is an aromatic amine. Can you tell why aliphatic amines are more basic than aniline although both of them contain an amino group? The key factors that effect the basicity are the electronegativity of the substituents, and the resonance stabilization.

Aliphatic amines and aniline both contain an amino group but their structural differences have a different effect on their basicity. Aniline has the amino group attached to a benzene ring. Benzene has an electron-withdrawing inductive effect. This effect decreases the electron density on the amino group. This makes aniline less basic.

On the other hand, aliphatic amines lack the electron withdrawing inductive effect of an aromatic ring. The amino group in aliphatic amines are typically attached to alkyl group. These alkyl groups have electron donating inductive effect. Alkyl groups increases the electron density on the nitrogen atom of amino group. This makes aliphatic amines more basic.

Another reason for lower basicity of aniline is resonance stabilization. In aniline, the lone pair of electrons on the nitrogen atom can delocalize into the pi system of the benzene ring. This reduces the availability of the lone pair of electrons for accepting a proton. As a result of this resonance stabilization, aniline is less basic.

In contrast, aliphatic amines lack significant resonance stabilization. There is no pi electron delocalization in aliphatic amines. This allows the lone pair of electrons on the nitrogen atom to be more readily available for accepting a proton. As a result aliphatic amines are more basic than aniline.

Small aliphatic amines, such as methylamine and ethylamine are highly soluble in water. This is due to their ability to form hydrogen bonds with water molecules. The amino group is polar because nitrogen atom is more electronegative than hydrogen atom. The presence of the amino group allows for hydrogen bonding between the amine and water molecules.

Aromatic amines, such as aniline have limited solubility in water. This is because of the presence of the aromatic ring. Aromatic ring has electron withdrawing nature. It withdraws electron density from nitrogen atom and makes it less polar. Hence the ability of aromatic amine to form hydrogen bonds with water, decreases. However, aromatic amines with additional polar functional groups might have improved solubility.

The Sandmeyer reaction is a chemical transformation that involves the conversion of an aromatic diazonium salt to various functional groups. The Sandmeyer reaction begins with the diazotization step. In this step, aniline is treated with sodium nitrite and hydrochloric acid, at low temperatures. This diazotization step converts the amino group into a diazonium salt. The resulting diazonium salt is benzene diazonium chloride.

The diazonium salt can undergo nucleophilic substitution reactions. During nucleophilic substitution the nucleophile replaces the diazonium group. We will use CuCl as the nucleophile. The diazonium group is replaced by the chloride group. This results in the formation of chlorobenzene. The Sandmeyer reaction allows for the conversion of a diazonium salt to various functional groups by selecting appropriate nucleophiles or electrophiles.

Azo compounds are a class of organic compounds that contain the azo functional group. The azo group consists of two nitrogen atoms connected by a double bond. The general structure of an azo compound can be represented as R-N=N-R. R represents organic substituents. These substituents can be aromatic or aliphatic groups.

Azo compounds are characterized by their vibrant colors. They are widely used as dyes and pigments. An example of azo compound is methyl orange. It is a pH indicator. A pH indicator is a substance that undergoes a color change in response to changes in the acidity or alkalinity of a solution. Under acidic conditions, methyl orange appears as a bright orange color. Under basic conditions, methyl orange turns to a red color.

Azo compounds are typically synthesized through azo coupling reactions. The first step in azo coupling reaction is the diazotization of an aromatic amine. This diazotization reaction converts the amino group of the aromatic amine into a diazonium salt. The diazonium salt then undergoes a coupling reaction with another aromatic compound. This aromatic compound is known as coupling component. The coupling component can be an aromatic amine, phenol, naphthol, or other suitable compounds.

Let us use phenol as the coupling component. The diazonium salt reacts with phenol through electrophilic aromatic substitution. The reaction occurs in the presence of a mild base such as sodium carbonate. The diazonium salt acts as an electrophile. It accepts electrons from the aromatic-ring of the coupling component. The electron rich aromatic-ring of the coupling component undergoes substitution. This results in the formation of the azo compound.

Hydrolysis of diazonium salt refers to a chemical reaction in which a diazonium salt reacts with water to produce a phenol. Diazo group of diazonium salt is replaced by hydroxyl group. Nitrogen gas is released in this reaction. For example, benzenediazonium chloride reacts with water to form phenol.

Diazonium salt can be reduced to primary aromatic amine in the presence of a reducing agent. Sodium sulfite acts as thereducing agent. For example, benzenediazonium chloride can be reduced to aniline in the presence of sodium sulfite. Other reducing agents, such as sodium nitrite or stannous chloride can also be used for the reduction of diazonium salts.