Explain why each of the following names is incorrect
1 answer:
<u>Explanation:</u>
Alkanes are the hydrocarbons in which single bonds are present between the carbon atoms
The suffix for alkane hydrocarbons used is '-ane'. The rules to write the nomenclature of alkanes follows:
- Select the longest possible continuous carbon chain and it will be the parent chain
- Numbering is done as such that the alkyl substituents are given the lowest number
- If different alkyl groups are present, they are written in an alphabetical order irrespective of their position in the carbon chain
- If two or more similar alkyl groups are present, the words, di, tri, tetra, and so on are used to specify the number of times alkyl groups appear
- If two or more alkyl groups are present and the branching occurs, the numbering is done which gives the minimum possible number to all the substituents
For the given options:
(a) 2,2-Dimethyl-6-ethylheptane
The longest possible carbon chain has 8 carbon atoms (prefix used is 'oct-') and not 7(prefix used is 'hept-').
Thus, the correct IUPAC name will be 2,2,6-trimethyloctane.
(b) 4-Ethyl-5,5-dimethylpentane
The longest possible carbon chain has 6 carbon atoms (prefix used is 'hex-') and not 5(prefix used is 'pent-').
Thus, the correct IUPAC name will be 4-isopropylhexane.
(c) 3-Ethyl-4,4-dimethylhexane
The substituents are not given the minimum possible number. Total sum of the number in original compound = [4 + 4 + 3] = 11
But, if both the methyl groups are placed at 3rd position, then total sum of the number = [3 + 3 + 4] = 10
Thus, the correct IUPAC name will be 4-ethyl-3,3-dimethylhexane
(d) 5,5,6-Trimethyloctane
The substituents are not given the minimum possible number. Total sum of the number in original compound = [5 + 5 + 6] = 16
But, if both the methyl groups are placed at 3rd position and 4th position, then total sum of the number = [3 + 3 + 4] = 10
Thus, the correct IUPAC name will be 3,3,4-trimethyloctane
(e) 2-Isopropyl-4-methylheptane
The longest possible carbon chain has 8 carbon atoms (prefix used is 'oct-') and not 7 (prefix used is 'hept-').
Thus, the correct IUPAC name will be 2,3,5-trimethyloctane
The structures of the compounds are attached below.
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