propane13dioic

Propane-1,3-dioic acid, commonly known as malonic acid, is a dicarboxylic acid with the molecular formula C3H4O4. It consists of a three-carbon chain with carboxyl groups at positions 1 and 3, giving the structure HOOC-CH2-COOH. In its pure form, malonic acid is a white crystalline solid that is soluble in water. It has a melting point around 135–136°C and, on heating, can decompose with release of carbon dioxide.

Malonic acid is a diprotic acid. Its pKa values are approximately 2.83 for the first dissociation and 5.69 for the second, reflecting the increasing acidity of the second carboxyl group as protons are removed. It readily undergoes decarboxylation upon heating, converting to acetic acid with loss of CO2. This property underpins its use in various synthetic strategies, including the malonic ester synthesis, where malonate esters are employed to introduce methylene groups into target molecules after hydrolysis and decarboxylation.

In organic synthesis, malonic acid serves as a versatile building block. Its derivatives, such as diesters, participate in methods to construct more complex carbon frameworks and to install carboxyl groups in a controlled manner. It is also explored as a potential intermediate in pharmaceutical and agrochemical synthesis, as well as in certain polymer-related applications.

Safety-wise, malonic acid is an irritant and should be handled with appropriate precautions to avoid skin, eye, or respiratory exposure. It is soluble in water and should be stored in a cool, dry place away from incompatible materials.