Here is a question from TPR:
What is the IUPAC name of the most stable product that is formed when 1,3-butadiene is reacted with an equal amount of HCl?
Correct Answer: 1-Chloro-2-butene
My answer: 3-Chloro-1-butene
To arrive at the correct answer, double bond from butadiene attacks the H bonded to Cl. Per Markovnikov electrophilic addition, positive charge forms on C3 of diene, while C4 binds to H. Now, if nucleophile Cl attacks at this positive charge, we would have 3-Chloro-1-butene. However, we have resonance occur where double bond becomes subsituted by carbons 2 and 3, with positive charge migrating to carbon 1. Positive charge on carbon is less favorable than positive charge on carbon 3 (1 vs. 2 carbons). If positive charge forms on carbon 1, nucleophile Cl attacks, forming the 1-Chloro-2-butene, TPR's answer.
Can someone explain to me please, why we are favoring stability of double bond over stability of the positive charge?
Thanks so much in advance!
Correct Answer: 1-Chloro-2-butene
My answer: 3-Chloro-1-butene
To arrive at the correct answer, double bond from butadiene attacks the H bonded to Cl. Per Markovnikov electrophilic addition, positive charge forms on C3 of diene, while C4 binds to H. Now, if nucleophile Cl attacks at this positive charge, we would have 3-Chloro-1-butene. However, we have resonance occur where double bond becomes subsituted by carbons 2 and 3, with positive charge migrating to carbon 1. Positive charge on carbon is less favorable than positive charge on carbon 3 (1 vs. 2 carbons). If positive charge forms on carbon 1, nucleophile Cl attacks, forming the 1-Chloro-2-butene, TPR's answer.
Can someone explain to me please, why we are favoring stability of double bond over stability of the positive charge?
Thanks so much in advance!
