A deprotonated molecule is represented by placing a negative charge (an extra electron) on the appropriate atom or group within the molecule. This negative charge indicates the loss of a proton (H+) from the molecule, resulting in the formation of a negatively charged species or an anion.
The placement of the negative charge depends on the specific molecule and the atom or group that lost the proton. Here are a few examples:
Deprotonated carboxylic acid: A carboxylic acid (R-COOH) can lose a proton from the acidic hydrogen, resulting in the formation of a carboxylate anion (R-COO-). The negative charge is placed on the oxygen atom of the carboxylate group (COO-).
Deprotonated amine: An amine (R-NH2) can lose a proton from the nitrogen atom, forming a deprotonated amine or an amide anion (R-NH-). The negative charge is placed on the nitrogen atom (N-).
Deprotonated alcohol: An alcohol (R-OH) can lose a proton from the hydroxyl group, resulting in the formation of an alkoxide anion (R-O-). The negative charge is placed on the oxygen atom (O-).
It's important to note that the negative charge represents the presence of an extra electron, which balances the overall charge of the molecule. The deprotonation process occurs when an acidic hydrogen is abstracted, typically by a base, leading to the formation of a negatively charged species or anion.