Question

Circle the functional groups in the following structures. State to which class (or classes) of compounds the structure belongs.

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(i)

Short answer

(a) ether

(b) carboxylic acid, alkene

(c) aldehyde, alkene

(d) aromatic hydrocarbon, ketone

(e) ester, alkene

(f) amide

(g) aromatic hydrocarbon, ether, nitrile

(h) amine, ester

(i) alcohol, carboxylic acid, amine

Step-by-step solution

Functional group

A functional group may be defined as an atom or a group of atoms that gives some characteristic properties to a compound.

The compounds containing hydroxy $\text{(}-\text{OH)}$functional group are classified as alcohols. Alcohols have the general formula$\text{R}-\text{OH}$, where $\text{R =}$alkyl group.

The functional group is which two alkyl groups are bonded to an oxygen atom are known as ethers. Ethers have the general formula$\text{R}-\text{O}-{\text{R}}^{/}$ , where$\text{R}$ and${\text{R}}^{/}$ represent alkyl groups.

The functional group in which carbon atom is bound to three other atoms namely, a single bond to a carbon atom, a double bond to an oxygen atom, and also a single bond to an oxygen atom. The singly bound oxygen atom is bound to another carbon

atom. This type of functional group is known as an ester.

The functional group for both aldehydes and ketones are the carbonyl group ($\text{C}=\text{O}$). In a ketone, there are two alkyl groups bonded to the carbonyl group whereas in an aldehyde, there is one alkyl group and one hydrogen atom bonded to the carbonyl group.

The functional group in which carboxyl group,$-\text{COOH}$group is present is referred to as carboxylic acid. Carboxylic acids have the general formula$\text{R}-\text{COOH}$ or $\text{R}-{\text{CO}}_2\text{H}$, where $\text{R =}$alkyl group.

Alkylated derivatives of ammonia${\text{(NH}}_3)$ are known as amines.

Acid derivatives resulting from the combination of an acid with ammonia${\text{(NH}}_3)$ or an amine are known as amides.

A compound containing cyano $(-\text{C}\equiv \text{N})$group is known as nitrile.

Alkenes are the hydrocarbons which contain carbon-carbon double bond $\text{(C}=\text{C)}$as their functional group.

Aromatic hydrocarbons are the benzene derivatives that are represented by a six membered ring containing three double bonds. They are also known as arenes.

Classification of compounds

(a)

It can be seen that the two alkyl groups are bonded to an oxygen atom. This type of functional group is known as an ether.

(b)

It can be seen that carboxyl group, $-\text{COOH}$ is present. This type of functional group is known as carboxylic acid. Also, it contains carbon-carbon double bond $(C=C)$which is known as alkene functional group.

(c)

It can be seen that there is one alkyl group and one hydrogen atom bonded to the carbonyl group$(C=C)$ which is known as the aldehyde functional group. Also, it contains carbon-carbon double bond $(C=C)$which is known as alkene functional group.

(d)

It can be seen that there is benzene derivative containing three double bonds which is known as the aromatic hydrocarbon. Also, it can be seen that there are two alkyl groups bonded to the carbonyl group $(C=C)$which is known as ketone functional group.

(e)

It can be seen that the carbon atom is bound to three other atoms namely, a single bond to a carbon atom, a double bond toan oxygen atom, and also a single bond to an oxygen atom. The singly bound oxygen atom is bound to another carbon atom. This type of functional group is known as an ester. Also, it contains carbon-carbon double bond $(C=C)$which is known as alkene functional group.

(f)

It is an acid derivative resulting from thecombination of an acid with an amine. This type of functional group is known as an amide.

(g)

It can be seen that there is benzene derivative containing three double bonds which is known as the aromatic hydrocarbon. Also, it can be seen that the two alkyl groups are bonded to an oxygen atom. This type of functional group is known as an ether. Lastly, cyano$(-C\equiv N)$ group is also present and this type of functional group is known as a nitrile.

(h)

It is an alkylated derivatives of ammonia$\left(N{H}_3\right)$ . This type of functional group is known as an amine. Again, it can be seen that the carbon atom is bound to three other atoms namely, a single bond to a carbon atom, a double bond to an oxygen atom, and also a single bond to an oxygen atom. The singly bound oxygen atom is bound to another carbon atom. This type of functional group is known as an ester.

(i)

It can be seen that hydroxy $(-\text{OH})$functional group is present. This type of functional group is known as an alcohol. Also, it can be seen that carboxyl group, $-\text{COOH}$ is present. This type of functional group is known as carboxylic acid. Lastly, it is an alkylated derivative of ammonia $\left(N{H}_3\right)$which is known as an amine.