Considering the isotopic substitution of hydrogen in alkyl groups, what is the correct decreasing or — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

The $+I$ effect order for isotopes of hydrogen is $-T > -D > -H$. This occurs because heavier isotopes have a shorter average bond length, concentrating electron density closer to the carbon atom, enhancing the electron-donating capability of the group. Hence, $-CT_3 > -CD_3 > -CH_3$.