Phthalic acid anhydride

85-44-9

Alkyd resins, plasticizers, hardener for resins, polyesters,
synthesis of phenolphthalein and phthaleins, many other dyes,
chlorinated products, pharmaceutical intermediates,
insecticides, diethyl phthalate, dimethyl phthalate, laboratory
reagent.

White crystalline needles.

Mild odour.

148.12

Using a reported vapor pressure of 2X10-4 mmHg at 20 °C and 
water solubility of 6200 ppm at 25 °, an estimated Henry's Law 
constant of 6.2X10-9 atm cm3/mol was calculated. 
Based on this 
estimated Henry's Law constant evaporation from water should be 
not be an important process (HSDB 2001).

A Koc of 36 has been estimated. 
Based on this estimated Koc,
phthalic anhydride will not adsorb to soils or sediments
(Kenaga 1980).

Phthalic anhydride will hydrolyze in moist soils and therefore 
will not leach into ground water (HAZARDTEXT 2001).

Corrosive. 
Combustible when exposed to heat or flame; can react
with oxidizing materials. 
Moderate explosion hazard in the form
of dust when exposed to flame. 
The production of this material
has caused many industrial explosions. 
Mixtures with copper
oxide or sodium nitrite explode when heated. 
Violent reaction
with nitric acid + sulfuric acid above 80 °C (Sax & Lewis 1989). 
Soluble in alcohol, carbon disulfide, and hot water.

Phthalic anhydride adsorbs light >290 nm and may therefore be
susceptible to direct sunlight photolysis. 
The estimated vapor
phase half-life in the atmosphere is 1.00 days, as a result of
addition of photochemically produced hyrdoxyl radicals
(Sadtler 1966) (GEMS 1986).

Photooxidation half-life in air:
202d - 20d, scientific judgement based upon an estimated rate
constant for vapor phase reaction with hydroxyl radicals in air
(Howard 1991).

A common air contaminant (Sax & Lewis 1989).

Phthalic anhydride hydrolyzes rapidly in water. 
An estimated
half-life of approx 1.5 min was calculated using a observed
rate constant of 7.9 x 10-3 sec-1 for hydrolysis in aqueous
solution at 25°C (Towle et al. 1968) (Hawkins 1975).

First-order hydrolysis half-life:
27min, scientific judgement based upon first order rate data
measured at pH of 7 and 25°C (k=4.29 x 10-4 s-1) (Howard 1991).

Acid rate constant (M(H+)-hr)-1:
k = 4.29 x 10-4 s-1, scientific judgement based upon first 
order rate data (t1/2=32s) measured at pH of 5.2 and 28°C 
(Howard 1991).

Aerobic half-life:
7d - 1d, scientific judgement based upon limited aqueous 
screening test data (Howard 1991).

Anaerobic half-life:
28d - 4d, scientific judgement based upon estimated 
unacclimated aqueous aerobic biodegradation half-life 
(Howard 1991).

Biodegradation:
85.2% by BOD
period: 14d
substance: 100 mg/l
sludge: 30 mg/l
(MITI 1992)

Biodegradation:
type: aerobic
inoculum: predominantly domestic sewage
concentration: 3 mg/l
degradation: 90 5 after 30 day
method: OECD Guide-line 301 D
(IUCLID 2000).

Biodegradation:
type: aerobic
inoculum: activated sludge, domestic, non-adapted
concentration: 10 mg/l
degradation: 99 % after 14 day
method: OECD Guide-line 301 E
(IUCLID 2000).

Confirmed to be biodegradable (Anon. 1987).

Percent theoretical BOD was reported to be 44 - 78 as a result
of incubation of 1 - 4 ppm with sewage inoculum (Heukelekian 
& Rand 1955).

Degradation of an initial concn of 2 ppm phthalic anhydride was
approx 21% after incubation with sewage (standard dilution
method) and 18% (seawater dilution method) for 5 days
(Takemoto et al 1981).

Mineralization of 33% of an initial concn of 9 ppm phthalic
anhydride incubated with activated sludge for 24 hr was
reported based on COD (Matsui et al. 1975).

Phthalic anhydride was reported to be significantly degraded in
Japanese MITI tests using activated sludge as inoculum
(Sasaki 1978).

Percent theoretical BOD was 73.46% in 5 days using dilution
water seeded with domestic sewage (Swope & Kenna 1950).

Phthalic anhydride did not bioconcentrate in Daphnia, Physa
(snail) or Gambusia (fish) (Ly & Metcalf 1975).

Bioconcentration factor (algae):
4053, Oedogonium (Lu & Metcalf 1975).

skn, rbt, 500 mg, 24 hr, mild; eye, rbt, 100 mg, severe (Sax &
Lewis 1989).

Poison by ingestion. 
Experimental teratogenic effects. 
A
corrosive eye, skin and mucous membrane irritant (Sax & Lewis
1989).

NCI carcinogenesis bioassay (feed); No evidence: mouse, rat
(Sax & Lewis 1989).