Question

Name the following hydrocarbons

a.

b.

c.

d.

Short answer

a.

1,2-Hexadiene

b.

1,3,5-Hexatriene

c.

2-Methyl-1-hexene

d.

3-Hexyne

Step-by-step solution

Saturated hydrocarbons

Saturated hydrocarbons are those which have a single covalent bond between atoms. E.g alkane. Whereas unsaturated hydrocarbons are those which have double or triple covalent bonds between atoms. For example, alkene, and alkyne.

Explanation

a.

The given structure has the longest continuous chain of six carbon atoms and two double bonds. To specify the locations of the double bonds in the chain, the carbon atoms are numbered in a manner to put the lower number on the double bond-bearing carbon atoms. As the double bonds are present on the first and second carbon. Hence, the name 1,2-Hexadiene.

1,2-Hexadiene

b.

The given structure has the longest continuous chain of six carbon atoms and three double bonds. To specify the locations of the double bonds in the chain, the carbon atoms are numbered (here numbering can be done from either side, as both sides give the same position for double bonds, i.e., 1,3,5). As there are three double bonds present at the first, third, and fifth carbon atoms. Hence, the name 1,3,5-Hexatriene.

1,3,5-Hexatriene

c.

The structure has the longest continuous chain of six carbon atoms. In the case of unsaturated hydrocarbons, the longest continuous chain is so selected as to include the double or triple bond. As 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 on the double bond. Hence the name 2-Methyl-1-hexene.

2-Methyl-1-hexene

d.

The given structure has the longest continuous chain of six carbon atoms and one triple bond. To specify the location of the triple bond in the chain, the carbon atoms are numbered from either side, which gives the same numbering to triple bonded carbon. As there is a triple bond at the third carbon. Hence, the name 3-Hexyne.

3-Hexyne