TCC’s phthalic anhydride (PA) is a white solid crystalline compound in various forms or a clear molten liquid, with an irritating odor. It is slightly soluble in hot water, hydrolysing to Phthalic Acid. PA is soluble in alcohol and carbon disulphide. It reacts with strong oxidants and responds violently when heated with copper oxide or sodium nitrite, to cause an explosion hazard.
Phthalic anhydride is presently obtained by catalytic oxidation of ortho–xylene or naphthalene. When separating the phthalic anhydride from production by products such as o–xylene in water, or maleic anhydride, a series of “switch condensers” is required. Phthalic anhydride can also be prepared from phthalic acid.
Phthalic anhydride is a precursor to a variety of reagents useful in organic synthesis. Important derivatives include phthalimide and its many derivatives.
Phthalic anhydride is widely used in industry for the production of certain dyes. A well-known application of this reactivity is the preparation of the anthroquinone dye quinizarin by reaction with para–chlorophenol followed by hydrolysis of the chloride.
One of the main uses of phthalic anhydride is the production of “phthalate” plasticizers such as Vestinol 9 DINP (DiIsoNonyl Phthalate) which are used to produce flexible PVC (Vinyl) products. These include, but are not limited to Wire & Cable applications, coated fabrics, roofing membranes and swimming pool liners.