Itaconic anhydride

WHITE TO CREAM CRYSTALLINE POWDER

Itaconic anhydride is used in immobilization of β-glucosidase. It undergoes estrification to obtain suitable monomers for emulsion polymerization itaconates.

To a flask equipped with a 12 mm diameter ground glass adaptor tube bent for downward distillation and joined to a 100 cm condenser is added 200 gm (0.95 mole) of citric acid monohydrate. An ice-cooled flask and a cold trap are connected to the condenser. The flask containing the citric acid is heated rapidly with a wide flame of the Meker burner so that in 12-15 min the distillation at 175-190°C is complete. The distillation is stopped earlier if the vapors in the reaction flask become yellow. Superheating of the citric acid will cause rearrangement to citraconic anhydride. The water is quickly separated from the distillate and the itaconic anhydride layer dried to afford 40-50 gm (37-47%), m.p. 67-68°C. Long time contact of the water with the anhydride causes it to hydrolyze to itaconic acid, m.p. 162-165°C.

Tetrahedron Letters, 25, p. 6027, 1984 DOI: 10.1016/S0040-4039(01)81751-2

Itaconic anhydride (ITA) is a biobased material that is obtained from renewable resources. It is produced from the pyrolysis of citric acid or by fermenting carbohydrates which forms itanoic acid. Itanoic acid can be dehydrated to form an anhydride. It is relatively more reactive that maleic anhydride and can be used as an alternating monomer that facilitates the introduction of polar functionalities in polymers.

Crystallise the anhydride from CHCl3/pet ether. It can be distilled under reduced pressure. Distillation at atmospheric pressure, or prolonged distillation causes rearrangement to citraconic anhydride (2-methylmaleic anhydride). If the material (as seen in the IR spectrum) contains much free acid, then heat with acetyl chloride or SOCl2, evaporate and distil at as high a vacuum as possible. The crude anhydride deposits crystals of itaconic acid on standing probably due to hydrolysis by H2O — store it in sealed ampoules under dry N2. [Skinner et al. Org Synth Coll Vol II 368 1943, IR: Nagai Bull Chem Soc Jpn 37 369 1964, Kelly & Segura J Am Chem Soc 56 2497 1934, Beilstein 17/11 V 66.]