Question

Complete the below reaction-

Answer 1

Through this reaction, dehydrogenation of the given compound will occur and the alcohol group will be reduced to water. The given compound whose dehydrogenation will occur is but-1, 3-diol, by hydrogenation one alcohol group will turn into a double bond.

Complete answer:
The product obtained will be 1, 2 butadiene or buta-1, 2-diene.
$C{{H}_{3}}-CH=C=C{{H}_{2}}+{{H}_{2}}O$
The reaction occurring in the above given question is dehydrogenation of but-1, 3-diol. Dehydrogenation reaction is a reaction in which there is removal of hydrogen from the compound, it can be both helpful and a problem.
In this reaction, when the compound but-1, 3-diol is subjected to dehydrogenation by addition of hydrogen and heat, the alcohol groups are removed and the single bonds are converted into double bonds with other carbon.
The hydrogen takes up on the two alcohol groups and the carbon from which the alcohol group is removed gets positively charged and that positive charge is satisfied by the negative charge on the adjacent atom. The hydrogen on that carbon atom is then removed.
The hydrogen that takes up on the alcohol group turns into water which is obtained as a by-product.
Thus the single bond of carbon which was with the alcohol group, becomes a double bond with the adjacent carbon atom. Thus, when both the alcohol groups are removed, two double bonds are introduced. And thus the name of the compound becomes but-1, 2-diene.

Note:
The double bond formed on the tertiary carbon can also form on the quaternary carbon, but as the product formed will not be stable it will not form in more amounts. The product in which the double bond of tertiary carbon is with secondary carbon is more stable and thus it will be formed in most amounts.