Can Alcohols Function as Both Nucleophiles and Electrophiles?

In the context of chemical reactions, we need to evaluate two statements regarding alcohols:

1. When R-OH is a nucleophile, the O-H bond is broken.
2. When R-OH is an electrophile, the R-O bond is broken.

To understand these statements, let’s break them down:

Statement A: When R-OH is a nucleophile, the O-H bond is broken.

This statement is false. When an alcohol (R-OH) acts as a nucleophile, it usually donates a pair of electrons from the oxygen atom to form a bond with an electrophile. In this process, the O-H bond does not break; instead, the oxygen atom utilizes its lone pairs to attack the electrophilic center. The O-H bond remains intact in this scenario.

Statement B: When R-OH is an electrophile, the R-O bond is broken.

This statement is true. When alcohol acts as an electrophile, it means that the carbon atom (R) is positively polarized, and this situation often occurs when R-OH is protonated to form R-OH⁺. In this state, the R-O bond can break, leading to the formation of a carbocation and a leaving group (water). Thus, breaking the R-O bond is a key aspect when alcohol acts as an electrophile.

In summary, Statement A is false while Statement B is true. Alcohols demonstrate versatility in reactions, functioning differently based on the reaction environment.