Pyromellitic dianhydride

Structural formula
General
Surname	Pyromellitic dianhydride
other names	Pyromellitic dianhydride PMDA 1,2,4,5-benzene tetracarboxylic acid dianhydride
Molecular formula	C 10 H 2 O 6
Brief description	white to beige needles
External identifiers / databases
CAS number 89-32-7 EC number 201-898-9 ECHA InfoCard 100.001.726 PubChem 6966 Wikidata Q1407366
properties
Molar mass	218.13 g mol −1
Physical state	firmly
density	1.68 g cm −3 (20 ° C)
Melting point	284-287 ° C
boiling point	397-400 ° C
solubility	decomposes in water
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary danger H and P phrases H: 317-318-334 P: 261-280-284-304 + 340-305 + 351 + 338 + 310
Toxicological data	2250 mg kg −1 ( LD 50 ,  rat ,  oral )
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Pyromellitic dianhydride is the anhydride of pyromellitic acid (1,2,4,5-benzene tetracarboxylic acid). PMDA is hygroscopic and forms pyromellitic acid with water. Pyromellitic dianhydride is a good electron acceptor and forms charge transfer complexes with electron-rich aromatics .

Occurrence

The substance is produced when mellitic acid is heated up strongly , but is obtained technically by oxidation of durol (1,2,4,5-tetramethylbenzene).

properties

Pyromellitic dianhydride is a flammable, hygroscopic white to beige solid that decomposes in water. With humidity it changes into pyromellitic acid, which is hardly soluble even in water.

use

PMDA is used in the production of temperature- resistant synthetic resins , for example for polyimides , which, among other things, serve as binders for electrical insulating varnishes .

safety instructions

PMDA has a sensitizing effect ( IgE antibodies detectable) and, especially in higher concentrations, irritates the airways .

Individual evidence

1. ↑ ^{a b c d e f g h} Entry on pyromellitic dianhydride in the GESTIS substance database of the IFA , accessed on July 23, 2016(JavaScript required) .
2. ↑ Entry on Benzene-1,2: 4,5-tetracarboxylic dianhydride in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
3. ↑ Entry on pyromellitic dianhydride in the ChemIDplus database of the United States National Library of Medicine (NLM) .
4. ^ ^{A b} Fieser and Fieser, Organic Chemistry, 2nd Edition, Verlag Chemie 1982 ISBN 3-527-25075-1 .
5. ↑ ^{a b} Entry on pyromellitic dianhydride. In: Römpp Online . Georg Thieme Verlag, accessed on June 15, 2014.