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 HO2C(CH2)nCHO. As illustrated by the behavior of the smallest member, glyoxylic acid, semialdehydes often exist as hydrates (geminal diols) HO2C(CH2)nCH(OH)2.
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.