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Phthalic Anhydride (99,8%) - India
- Origin
- : India
- CAS Number
- : 85-44-9
- HS Code
- : 2917.35.00
Basic Info
- IUPAC Name
- : 2-benzofuran-1,3-dione
- Molecular Formula
- : C8H4O3
- Molecular Weight (g/mol)
- : 148.1200
- Synonyms & Trade Names
- : Phthalic anhydride; PA; Isobenzofuran-1,3-dione; 1,3-Isobenzofurandione
- Purity / Assay (%)
- : 99.5% min
- Grade / Quality Level
- : Industrial Grade
- Physical Form
- : Solid
- Concentration
- : Pure substance
- Appearance / Color
- : White to off-white solid
- Odor
- : Choking, acrid
- Melting Point (°C)
- : 131.0000
- Boiling Point (°C)
- : 295
- Density (g/cm³)
- : 1.5300
- Solubility in Water
- : Reacts with water
- Signal Word
- : Danger
- UN Number
- : 2214
- GHS Hazard Class
- : Acute toxic; Skin corrosive; Respiratory sensitizer
- H-Statements
- : H302|H314|H317|H332|H334
- P-Statements
- : P260|P264|P271|P272|P273|P280|P284|P301+P330+P331
- REACH Status
- : Registered
- Drug Precursor Status
- : Non-precursor
- Storage Class (GHS)
- : 8
- Storage Conditions
- : Dry; away from moisture; sealed
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Brief Overview
Phthalic anhydride, represented by the formula C6H4(CO)2O, serves as the anhydride of phthalic acid and is a significant commercial form of the acid. It marked the pioneering use of a dicarboxylic acid anhydride on a large scale, with this white solid playing a crucial role in industrial chemistry, particularly in the extensive production of plasticizers for plastics. The estimated global production volume in 2000 reached about 3 million tonnes annually.
Manufacturing Process:
Discovered by Auguste Laurent in 1836, phthalic anhydride is currently synthesized through various methods, including the oxidation of naphthalene or ortho-xylene. In these processes, vanadium pentoxide (V2O5) serves as the active oxidant, playing a key role in multiple steps and being regenerated by molecular oxygen. Starting from o-xylene, the oxidation reaction is run at about 320–400 °C and has the following stoichiometry:
C6H4(CH3)2 + 3 O2 → C6H4(CO)2O + 3 H2O
The reaction proceeds with about 70% selectivity. About 10% of maleic anhydride is also produced: C6H4(CH3)2 + 7.5 O2 → C4H2O3 +4 H2O + 4 CO2
Phthalic anhydride and maleic anhydride are recovered by distillation by a series of switch condensers.
The naphthalene route (the Gibbs phthalic anhydride process or the Gibbs–Wohg naphthalene oxidation reaction), a process whose use has declined in compared to the o-xylene route, has the following mechanism:
Phthalic anhydride can also be prepared from phthalic acid by simple dehydration.