Question

Name the following hydrocarbons:

a.

b.

c.

d.

Short answer

a. 2,3-dimethyl-1,3-butadiene.

b. 2,4-Hexadiene

c. 2,2-dimethyl butane

d. 2-Methyl-1-propene

Step-by-step solution

Hydrocarbons

Hydrocarbon comprises carbon and hydrogen. These are aliphatic and aromatic hydrocarbons. Aliphatic hydrocarbons are the ones with chain and cyclic form whereas aromatic hydrocarbons are the ones in planar ring form.

Subpart (a).

The structure has the longest continuous chain of four carbon atoms.

In the unsaturated hydrocarbons, the longest chain is selected as such in which the double or triple bond carbon gets the lowest numbering.

Therefore in this compound, as there are two double bonds at the terminal ends, and two methyl groups are present on the middle carbon, the numbering is performed from terminal carbon and the name of the compound is 2,3-dimethyl-1,3-butadiene.

Subpart (b).

The structure has the longest continuous chain of six carbon atoms and two double bonds which are symmetry.

Therefore, the numbering can be done from either side. To specify the locations of the double bonds in the chain, the carbon atoms are numbered, and at the second and fourth carbon double bond is present.

Hence, the name of the compound is 2,4-Hexadiene.

Subpart (c).

The structure has the longest continuous chain of four carbon atoms and there are two methyl groups attached to the chain carbon atom as substituents. To specify the location of the substituents, the chain carbon atoms are numbered in a manner to put the lower number on the substituents bearing carbon atom.

Therefore, the name of the hydrocarbon is 2,2-dimethyl butane.

Subpart (d).

The structure has the longest continuous chain of three carbon atoms.

In the case of unsaturated hydrocarbons, the longest chain includes the double or triple bond.

In the given compound there is one double bond and one methyl group attached to the chain carbon atom as a substituent. To specify the location of the double bond as well as the substituent in the chain, the carbon atoms are numbered in a manner to put the lower number to the double bond-bearing carbon atom.

As there are three carbon atoms with one double bond, hence the name propene, Therefore, the name of the given hydrocarbon is 2-Methyl-1-propene.