Question

Write the stability of given alcohols
$C{{H}_{3}}OH, C{{H}_{3}}C{{H}_{2}}OH, C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}OH$

Answer 1

Hint: The stability of alcohols depends on the strength of the C—O bond in the alcohols. Greater the strength of the C—O bond or stronger the C—O bond, greater is the stability of the alcohols. Now, check the stability of the C—O bond in the above alcohols and then write their stability order.

Complete step by step answer:
As mentioned in the hint, we know that the stability of the alcohols is directly proportional to the C—O bond in the alcohols. Stronger the bond, greater is the stability.
The strength of the C—O in alcohols further depends on the electron deficiency of the carbon atom in the alcohol. Greater the electrophilicity (electron deficiency) on carbon atom, greater is the bond strength and hence the stability.
Electron donating groups i.e. methyl, ethyl etc. decreases the electrophilicity of carbon atoms and hence the bond strength and the stability. on the other hand, electron
withdrawing groups i.e. alkyl halides, hydroxyl gap etc. increases the electrophilicity on the carbon atom and hence the bond strength and the stability.
In $C{{H}_ {3}} OH$, there is no group attached and the bond strength of C—O bond is stronger in this and hence the stability of $C{{H}_{3}}OH$ is greater than other two alcohols. Because in ${{{CH}}_{3}}C{{H}_{2}}OH$, there is methyl group(-$C{{H}_{3}}$) which being electron donating gives the electron to the carbon atom and hence the electrophilicity on carbon atom decreases and hence the bond strength of C—O bond decreases and hence the stability but more than ${{{CH}}_{3}}C{{H}_{2}}C{{H}_{2}}OH$ , in which there is ethyl group( -${{{CH}}_{3}}C{{H}_{2}}$) which being more stronger electron donating group than methyl, tends to more decrease the electrophilicity of the carbon atom and hence the bond strength decreases further and hence the stability and is least stable of above three.

Therefore, the order of stability of alcohols is:
${{{CH}}_{3}}OH > C{{H}_{3}}C{{H}_{2}}OH > C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}OH$

Note: Be careful while arranging them and don’t arrange them on the basis of reactivity. Always keep in mind that the stability and reactivity are always inversely proportional to one another. The one with more stability has least reactivity and vice-versa.