Phthalic Anhydride

Phthalic anhydride is a resin and plasticizer intermediate. It goes into alkyd resins, unsaturated polyester resins, and phthalate plasticizers such as DOP and DBP. Upstream, it is made from ortho xylene — a solvent we also stock.

The CAS number is 85-44-9 and the HSN code is 2917 35 00. It is commonly abbreviated PA (PAN in Indian trade usage), and also appears as phthalic acid anhydride, 1,2-benzenedicarboxylic anhydride, or isobenzofuran-1,3-dione.

We stock Technical Grade phthalic anhydride to IS 5158 : 1987 (Reaffirmed 2018). Against I G Petrochemicals' (IGPL) published specification, total available acidity (as C8H4O3) is 99.8 % by mass min, crystallizing point 130.8 °C min, colour of molten material 20 Hazen (APHA) max, free acidity 0.1 % by mass max, and ash 50 ppm max. Industrial and Technical grades are offered.

They are different compounds. Phthalic anhydride (CAS 85-44-9) is supplied as flakes with a crystallizing point of 130.8 °C min, and its specification quotes total available acidity as C8H4O3. Maleic anhydride is the smaller C4H2O3 anhydride, and in the phthalic anhydride specification it is capped as an impurity at 0.1 % by mass max, together with other oxidizable impurities. Both feed resin production, and we supply both from stock in Chennai.

Yes — it is classified UN 2214, Class 8 corrosive solid (Packing Group III). It causes skin, eye and respiratory irritation, and molten material causes burns, so handle it with protective equipment in a well-ventilated area. Store cool and dry, away from moisture, alkalis and oxidisers. Shelf life is 24 months from manufacture.

Yes. We hold phthalic anhydride flakes in 25 kg bags at our Redhills, Chennai warehouse, with 1000 kg jumbo bags also available and dispatch across South India. Lead time runs ex-stock to 5 working days; order sizes depend on packaging and current stock. Call or WhatsApp +91 86087 80096 for a quote — the branded TDS and MSDS are downloadable from this page.