which of the following alkane names is correct?
a)2-methyl-3-propylhexane
b)1-methylnonane
c)1,2-dimethylhexane
d)4,5-dimethylpentane
e)all of the above names are correct
The correct alkane name among the options given is:
d) 4,5-dimethylpentane
The other options have errors in their nomenclature. Let's break down each option to understand why:
a) 2-methyl-3-propylhexane
This option is incorrect because the numbering of the carbon chain starts from the end closest to the substituent groups. In this case, the correct name would be 3-methyl-2-propylhexane.
b) 1-methylnonane
This option is also incorrect. The substituents should be indicated by their position in the carbon chain. A correct name would be 1-methyl-4-nonane.
c) 1,2-dimethylhexane
This option is incorrect because the numbering starts from the end closest to the substituent groups. The correct name would be 2,3-dimethylhexane.
Therefore, the only correct name is:
d) 4,5-dimethylpentane
To determine whether each alkane name is correct, we need to understand the rules for naming alkanes using the IUPAC (International Union of Pure and Applied Chemistry) system.
According to the IUPAC naming rules:
1. The parent chain should be the longest continuous carbon chain. The name of the alkane is derived from this parent chain.
2. The substituents (methyl, ethyl, propyl, etc.) should be named and assigned a position number based on their location on the parent chain.
3. The substituents should be listed in alphabetical order, regardless of their position on the chain.
Let's analyze each option:
a) 2-methyl-3-propylhexane:
In this case, the parent chain is a hexane (6 carbon atoms). The substituents are a methyl group (1 carbon) attached to the second carbon atom, and a propyl group (3 carbon atoms) attached to the third carbon atom. The name correctly follows the IUPAC rules.
b) 1-methylnonane:
Here, the parent chain is a nonane (9 carbon atoms). The substituent is a methyl group attached to the first carbon atom. The name is correct according to IUPAC.
c) 1,2-dimethylhexane:
The parent chain is a hexane (6 carbon atoms). There are two methyl groups attached to the first and second carbon atoms. The substituents are named and numbered correctly based on their position. The name adheres to IUPAC rules.
d) 4,5-dimethylpentane:
In this case, the parent chain is a pentane (5 carbon atoms). There are two methyl groups attached to the fourth and fifth carbon atoms. The substituents are correctly named and numbered according to their position. The name follows IUPAC conventions.
In conclusion, all of the provided alkane names are correct (option e). They follow the IUPAC naming rules accurately.