Question

What is the IUPAC name for the following? how the hell it can be butene!
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Answer 1

Answer: The IUPAC name of the given compound is 3-methylbutene.

Explanation: The compound has has double bond carbon which means it is alkene. When we count the carbon for the IUPAC naming then we prioritize  double bond then longest chain of carbon + subsitituent. In this case we priortize double bond and start counting from it to the left carbon which has double bond and count till the last carbon so that we can get the longest chain. Thus, It is butene.