Question

What are the order of rates of oxidation with $HI{O}_4$ of the following diols?
$\left(a\right)M{e}_{2}C\left(OH\right)C\left(OH\right)M{e}_2$
$\left(b\right)M{e}_{2}C\left(OH\right)CH\left(OH\right)Me$
$\left(c\right)C{H}_{2}OHC{H}_{2}OH$
$\left(d\right)MeCH\left(OH\right)C\left(OH\right)Me$

• A. $a<b<d<c$ (steric factor)
• B. $a<d<b<c$ (steric factor)
• C. $c<b<d<a$ (steric factor)
• D. $d<c<a<d$ (steric factor)

Answer 1

The correct option is A $a<b<d<c$ (steric factor)

Any diol in which the two hydroxy functional groups are attached to adjacent carbon atoms, called vicinal diols. Given all diols are vicinal diols.

The rate of the oxidation of vicinal diols with periodic acid depends on the steric factor.

More methyl group in the diol increases the hinderance.

Higher the steric hindrance, less is the rate of oxidation with $HI{O}_4$

hence, the order is $a<b<d<c$.

Option A is correct.