Question

Write IUPAC names for these alkanes. (a) CCCC(CCC(C)C)C(C)C (b) CCCCCC(CCC)(CCC)C(C)C

Short answer

Question: What are the IUPAC names for the following alkanes: a) CH3-CH(CH3)-CH2-CH(CH3)-CH2-CH2-CH3 b) CH3-CH2-CH2-CH2-CH(CH3)2-CH(CH3)-CH2-CH2-CH3

Step-by-step solution

(a) Identify the parent chain and number the carbon atoms

For the first alkane, we can see that the longest carbon chain has 7 carbon atoms. We will number the carbon atoms from left to right, giving the substituent groups the lowest possible numbering, as follows: 1, 2, 3, 4, 5, 6, and 7.

(a) Identify the substituent groups and their positions

There are two methyl groups (CH3) in the molecule. One is attached to the second carbon atom, and the other one is attached to the fourth carbon atom.

(a) Write the IUPAC name

Now, we can write the IUPAC name for the alkane. The parent chain has 7 carbon atoms, so the alkane's base name is heptane. The substituent groups are methyl groups, which are attached to the 2nd and 4th carbon atoms. Thus, the IUPAC name for this alkane is 2,4-dimethylheptane.

(b) Identify the parent chain and number the carbon atoms

For the second alkane, the longest carbon chain has 9 carbon atoms. We will number the carbon atoms from left to right, considering the lowest possible numbering for the substituent groups, as follows: 1, 2, 3, 4, 5, 6, 7, 8, and 9.

(b) Identify the substituent groups and their positions

There are three methyl groups (CH3) in the molecule. Two are attached to the fifth carbon atom and one is attached to the ninth carbon atom. Additionally, there is an isopropyl group (CH(CH3)2) attached to the sixth carbon atom.

(b) Write the IUPAC name

The parent chain has 9 carbon atoms, so the alkane's base name is nonane. The substituent groups are methyl and isopropyl groups. The methyl groups are attached to the 5th (2 groups) and 9th carbon atoms, and the isopropyl group is attached to the 6th carbon atom. Thus, the IUPAC name for this alkane is 5,5,9-trimethyl-6-isopropylnonane.