Question

Which of the following is the correct IUPAC name of the given organic compound (X)? The structure of compound $ X $ is as follows: $ \text{H}_3\text{C} - \text{CH}_3 - \text{CH} = \text{CH} - \text{H} - \text{Br} $

• A. 2-Bromo-2-methylbut-2-ene
• B. 3-Bromo-3-methylprop-2-ene
• C. 1-Bromo-2-methylbut-2-ene
• D. 4-Bromo-3-methylbut-2-ene

Hint:

When naming organic compounds, always prioritize giving the lowest possible number to the position of the double bond and substituents. If there are multiple substituents, assign the lowest possible sum of numbers.

Answer 1

The Correct Option is C

Step 1: Identify the longest carbon chain.
The longest continuous chain that includes the double bond consists of 4 carbon atoms, so the base name is "butene" (indicating a 4-carbon alkene). 
Step 2: Number the chain.
Number the chain such that the double bond gets the lowest possible number. Since the double bond is between carbon 2 and carbon 3, we assign numbers to the carbon chain as follows: \[ \text{H}_3\text{C} - \text{CH}_3 - \text{CH} = \text{CH} - \text{H} - \text{Br} \] The double bond is between carbons 2 and 3, so the compound is "but-2-ene." 
Step 3: Identify the substituents.
There is a methyl group (CH₃) attached to carbon 2.
There is a bromo group (Br) attached to carbon 1.
Step 4: Assign positions to the substituents.
The methyl group is on carbon 2, and the bromo group is on carbon 1. The substituents should be numbered to give the lowest possible numbers, so the correct positions are:
Methyl group on carbon 2
Bromo group on carbon 1
Step 5: Construct the IUPAC name.
The name of the compound is 1-Bromo-2-methylbut-2-ene, where:
"But" indicates the 4-carbon chain (butene).
"2-ene" indicates the double bond between carbons 2 and 3.
"2-methyl" refers to the methyl group on carbon 2.
"1-bromo" refers to the bromo group on carbon 1.
Thus, the correct name is 1-Bromo-2-methylbut-2-ene.