Question

The best reagent to convert pent-3-en-2-ol into pent -3-en-2-one is:
A)- acidic dichromate
B)- acidic permanganate
C)- chromic anhydride in glacial acetic acid
D)- none of these

Answer 1

Hint : A reagent is a substance or compound added to a system to cause a chemical reaction, or added to test if a reaction occurs. The terms reactant and reagent are often used interchangeably, however, a reactant is more specifically a substance consumed in the course of a chemical reaction.

Complete Step By Step Answer:
Redox is a type of chemical reaction in which the oxidation states of atoms are changed. Redox reactions are characterized by the actual or formal transfer of electrons between chemical species, most often with one species undergoing oxidation while another species undergoes reduction.
Since. It has the reagent substance which is a compound added to a system to cause a chemical reaction, or added to test if a reaction occurs.
$C{H_3}CH\left( {OH} \right)CH = CHC{H_3} \to C{H_3} - CO - CH = CHC{H_3}$
The above reaction is an example of oxidation reaction. Pyridinium chlorochromate is a mild oxidizing agent that oxidizes primary alcohol to aldehydes and secondary alcohols to ketones.
It does not affect any group and therefore has high selectivity for oxidation of alcohols.
Whereas, in acidic permanganate, other functional acidic dichromate, chromic anhydride in glacial acetic acid is strong oxidizing agents. Therefore, none of these are used for reagent to convert pent-3-en-2-ol into pent -3-en-2-one.
Hence , option D is the correct answer.

Note :
Nitriles can be converted to 1° amines by reaction with $LiAl{H_4}$ . During this reaction the hydride nucleophile attacks the electrophilic carbon in the nitrile to form an imine anion. Once stabilized by a Lewis acid-base complexation the imine salt can accept a second hydride to form a dianion.