The major product formed upon addition of 1 mole of HBr in the following reaction is :
Major Product ?
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This reaction involves electrophilic addition of HBr to a conjugated diene. The major product is governed by Markovnikov's rule and stability of the carbocation intermediate. The initial protonation occurs at the less substituted alkene, forming a more stable allylic carbocation. Bromide then adds to the carbocation's more substituted carbon.
The carbocation stability follows: tertiary allylic > secondary allylic. The reaction proceeds via 1,4-addition (conjugate addition) due to the stability of the intermediate allylic carbocation, giving the thermodynamic product.
Final Answer: The third option (with bromine on the terminal carbon of the diene system) is the major product.