Question

Which has greater -inductive effect -oh or -och3?

Answer 1

Answer:

Negative inductive effect (-I effect) or electron withdrawing effect is shown by the groups which have more electronegativity.

 

OCH3 group is more electron withdrawing (i.e, shows more -I effect) than the OH group.

Explanation:

The reason is that, there are two lone pairs of oxygen. Oxygen has a smaller size, so in case of OCH3, the methyl group is close to the lone pair electrons, which leads to Steric repulsion. Due to this, a slight positive charge is developed on Oxygen atom, and we know that positively charged ions are more electronegative, as they are electron deficient, and they definitely are in want of electrons. So, this positive charge increases the electronegativity of O atom, due to which its electron withdrawing effect increases.

 

However, in case of OH, the H atom is comparatively much much smaller than O, so here no Steric repulsion takes place. OH shows -I effect just due to the electronegativity value of Oxygen.

Answer 2

$-OCH_3$ Group has Greater Inductive Effect

Explanation:

• Positive inductive effect or +I effect or electron-donating effect is shown by the groups that have less electronegativity while negative inductive effect (-I effect) or electron-withdrawing effect is shown by the groups which have more electronegativity

• OH is the electron-donating group as it has a lone pair of electrons that means it shows positive inductive effect while -$OCH_3$ is an electron-withdrawing group that means it shows a negative inductive effect

∴ Concluding,$-OCH_3$ group has a greater inductive effect(i.e, shows more -I effect) than the OH group.