In organic chemistry, a semialdehyde is a compound containing an aldehyde and a carboxylic acid functional groups. Semialdehydes are common in biochemistry.[1] The simplest semialdehydes have the formula . As illustrated by the behavior of the smallest member, glyoxylic acid, semialdehydes often exist as hydrates (geminal diols) .
Some of semialdehydes and their parent dicarboxylic acids are listed below.
| Semialdehyde | Dicarboxylic acid | |
|---|---|---|
| malonic semialdehyde | malonic acid | |
| tartronic semialdehyde | tartronic acid | |
| succinic semialdehyde | succinic acid | |
| methylmalonic semialdehyde | methylmalonic acid | |
| aspartic-4-semialdehyde | aspartic acid | |
| glutamic-1-semialdehyde | glutamic acid | |
| glutamic-5-semialdehyde | glutamic acid | |
| 4-hydroxymuconic-semialdehyde | 4-Hydroxymuconic acid | |
| 2-amino-3-carboxymuconic semialdehyde | 2-hydroxy-4-carboxymuconic acid | |
| alpha-aminoadipic semialdehyde | alpha-aminoadipic acid |
Although structurally related to semialdehydes, dicarboxylic acids are rarely biochemical precursors to them.