Question

$1,4-$ addition in butadiene gives kinetically favored product.
If this is true enter 1, else enter 0.

Answer 1

The statement is false.

It results from Markovnikov protonation at position 1, resulting in a resonance-stabilized allylic cation. The 1,4 adduct places the larger Br atom at a less congested site and includes a more highly substituted alkene moiety. The thermodynamic product is more stable and is favoured under thermodynamic control as compared to 1,2 addition which is kintetically controlled. The initial step in which a proton bonds to carbon. The first step is the rate determining step, as indicated by the large activation energy. The second faster step is the product determining step, and there are two reaction paths (both for 1,2-addition and for 1,4-addition). The 1,2-addition has a smaller activation energy than 1,4-addition, but the 1,4-product is more stable than the 1,2-product. At low temperatures, 1,2 product is termed kinetically controlled. At higher temperatures, equilibrium is established between the products, and the thermodynamically favored 1,4-product dominates.