A sequence of chemical reactions, starting with 2-methylprop-1-ene, is shown in the flow chart - HSC - SSCE Chemistry - Question 26 - 2021 - Paper 1

Compound B results from the oxidation of compound A (2-methylpropan-2-ol) with acidified KMnO4, forming 2-methylpropan-2-one:

    O
    ||
H3C-C-CH3
    |
    H

Compound C is formed through a substitution reaction of compound B with concentrated HCl and ZnCl2, resulting in 2-chloro-2-methylpropane:

    Cl
    |
H3C-C-CH3
    |
    H

Compound D is produced by refluxing compound C with methanol and concentrated H2SO4, yielding methyl 2-methylpropanoate:

        O
        ||
H3C-C-CH3
        |
        OCH3

1. Reflux retains the volatile reactants and products, preventing loss of materials during the reaction.
2. It allows the reaction to proceed at a higher temperature without boiling off the solvents or reactants.