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Phthalic anhydride

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Phthalic anhydride Basic information

Product Name:
Phthalic anhydride
CAS:
85-44-9
MF:
C8H4O3
MW:
148.12
EINECS:
201-607-5
Mol File:
85-44-9.mol
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Phthalic anhydride Chemical Properties

Melting point:
131-134 °C(lit.)
Boiling point:
284 °C(lit.)
Density 
1,53 g/cm3
vapor density 
5.1 (vs air)
vapor pressure 
<0.01 mm Hg ( 20 °C)
refractive index 
1.4500 (estimate)
Flash point:
152 °C
storage temp. 
Store at RT.
solubility 
6g/l (slow decomposition)
form 
Flaky Crystals
color 
White
PH
2 (6g/l, H2O, 20℃)
explosive limit
1.7-10.5%(V)
Water Solubility 
6 g/L (20 ºC)
Sensitive 
Moisture Sensitive
Merck 
14,7372
BRN 
118515
Henry's Law Constant
6.29 at 20 °C (approximate - calculated from water solubility and vapor pressure)
Exposure limits
NIOSH REL: TWA 6 mg/m3 (1 ppm), IDLH 60 mg/m3; OSHA PEL: TWA 12 mg/m3 (2 ppm); ACGIH TLV: TWA 1 ppm (adopted).
Stability:
Stable. Combustible. Incompatible with strong oxidizing agents, strong bases, moisture, strong acids. Dust may form an explosive mixture with air.
CAS DataBase Reference
85-44-9(CAS DataBase Reference)
NIST Chemistry Reference
Phthalic anhydride(85-44-9)
EPA Substance Registry System
Phthalic anhydride (85-44-9)
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Safety Information

Hazard Codes 
Xn
Risk Statements 
22-37/38-41-42/43
Safety Statements 
23-24/25-26-37/39-46-22
RIDADR 
2214
WGK Germany 
1
RTECS 
TI3150000
10-21
Autoignition Temperature
580 °C
TSCA 
Yes
HazardClass 
8
PackingGroup 
III
HS Code 
29173500
Hazardous Substances Data
85-44-9(Hazardous Substances Data)
Toxicity
LD50 orally in Rabbit: 1530 mg/kg LD50 dermal Rabbit > 3160 mg/kg

MSDS

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Phthalic anhydride Usage And Synthesis

Description

Phthalic anhydride is the organic compound with the formula C6H4(CO)2O. It is the anhydride of phthalic acid. This colourless solid is an important industrial chemical, especially for the large-scale production of plasticizers for plastics. In 2000, the world wide production volume of phthalic anhydride is estimated to be about 3 232 000 tones per year.

Chemical Properties

Phthalic Anhydride is moderately flammable, white solid (flake) or a clear, colorless, mobile liquid (molten) Characteristic, acrid, choking odor

Chemical Properties

white crystalline solid with choking odour

Physical properties

Colorless to pale cream crystals with a characteristic, choking odor. Moisture sensitive. Odor threshold concentration is 53 ppb (quoted, Amoore and Hautala, 1983).

Uses

Intermediate for Plastizers, Paints, Dyes and Pigments, Polyester Resins

Uses

Phthalic Anhydride is an organic compound and the anhydride of phthalic acid (P384480). Phthalic Anhydride is an important industrial chemical commonly used in large-scale production of plasticizers f or plastics. Recent research have also evaluated Phthalic Anhydride as potential antibacterial agent.

Uses

manufacture of phthaleins, phthalates, benzoic acid, synthetic indigo, artificial resins (glyptal).

Definition

ChEBI: The cyclic dicarboxylic anhydride that is the anhydride of phthalic acid.

General Description

A colorless to white lustrous solid in the form of needles with a mild distinctive odor. Moderately toxic by inhalation or ingestion and a skin irritant. Melting point 64°F Flash point 305°F. Forms a corrosive solution when mixed with water. Used in the manufacture of materials such as artificial resins.

Air & Water Reactions

Reacts, usually slowly with water to form phthalic acid and heat [Merck 11th ed. 1989]. The phthalic acid is somewhat soluble in water.

Reactivity Profile

Phthalic anhydride reacts exothermically with water. The reactions are sometimes slow, but can become violent when local heating accelerates their rate. Acids accelerate the reaction with water. Incompatible with acids, strong oxidizing agents, alcohols, amines, and bases. Undergoes exothmeric nitration with fuming nitric acid-sulfuric acid and may give mixtures of the potentially explosive phthaloyl nitrates or nitrites or their nitro derivatives [Chem. & Ind. 20:790. 1972]. Phthalic anhydride reacts violently with CuO at elevated temperatures [Park, Chang-Man, Richard J. Sheehan. hthalic Acids and Other Benzenepolycarboxylic Acids Kirk-Othmer Encyclopedia of Chemical Technology. John Wiley & Sons, Inc. 2005]. Mixtures of Phthalic anhydride and anhydrous CO2 explode violently if heated [eaflet No. 5, Inst. of Chem., London, 1940].

Health Hazard

Solid irritates skin and eyes, causing coughing and sneezing. Liquid causes severe thermal burns.

Fire Hazard

Combustible material: may burn but does not ignite readily. Substance will react with water (some violently) releasing flammable, toxic or corrosive gases and runoff. When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion hazards. Most vapors are heavier than air. They will spread along ground and collect in low or confined areas (sewers, basements, tanks). Vapors may travel to source of ignition and flash back. Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated or if contaminated with water.

Pharmaceutical Applications

Phthalic anhydride reacted with cellulose acetate forms cellulose acetate phthalate (CAP), a common enteric coating excipient that has also been shown to have antiviral activity. Phthalic anhydride is a degradation product of CAP.

Contact allergens

Phthalic anhydride is used in the manufacture of unsaturated polyesters and as a curing agent for epoxy resins. When used as a pigment, it can be responsible for sensitization in ceramic workers. Phthalic anhydride per se is not responsible for the sensitization to the resin used in nail varnishes phthalic anhydride/trimellitic anhydride/ glycols copolymer.

Safety Profile

Poison by ingestion. Experimental teratogenic effects. A corrosive eye, skin , and mucous membrane irritant. A common air contaminant. Combustible when exposed to heat or flame; can react with oxidzing materials. Moderate explosion hazard in the form of dust when exposed to flame. The production of ths 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℃. To fight fire, use CO2, dry chemical. Used in plasticizers, polyester resins, and alkyd resins, dyes, and drugs. See also ANHYDRIDES.

Chemical Synthesis

Phthalic anhydride is a precursor to a variety of reagents useful in organic synthesis. Important derivatives include phthalimide and its many derivatives. Chiral alcohols form half-esters (see above), and these derivatives are often resolvable because they form diastereomeric salts with chiral amines such as brucine. A related ring - opening reaction involves peroxides to give the useful peroxy acid:
C6H4(CO)2O + H2O2 → C6H4(CO3H)CO2H.

Chemical Synthesis

Phthalic anhydride is a versatile intermediate in organic chemistry, in part because it is bi functional and cheaply available. It undergoes hydrolysis and alcoholysis. Hydrolysis by hot water forms ortho-phthalic acid. This process is reversible: Phthalic anhydride reforms upon heating the acid above 180 °C. Hydrolysis of anhydrides is not typically a reversible process. However, phthalic acid is easily dehydrated to form phthalic anhydride due to the creation of a thermo dynamically favorable 5-membered ring.

Chemical Synthesis

Phthalic anhydride was first reported in 1836 by Auguste Laurent. It is presently obtained by catalytic oxidation of ortho-xylene and naphthalene ("Gibbs phthalic anhydride process"):
C6H4(CH3)2 + 3 O2→C6H4(CO)2O + 3 H2O
C10H8 + 4.5 O2→ C6H4(CO)2O + 2 H2O + 2 CO2 The catalyst that is used for the oxidation of xylene is a modified vanadium pent oxide (V2O5). When separating the phthalic anhydride from byproducts 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:.

Potential Exposure

Phthalic anhydride is used in plasticizers; in the manufacture of phthaleins; benzoic acid; alkyd and polyester resins; synthetic indigo; and phthalic acid;which is used as a plasticizer for vinyl resins. To a lesser extent, it is used in the production of alizarin, dye, anthranilic acid; anthraquinone, diethyl phthalate; dimethyl phthalate; erythrosine, isophthalic acid; methylaniline, phenolphthalein, phthalamide, sulfathalidine, and terephthalic acid. It has also found uses as a pesticide intermediate.

Environmental Fate

Chemical/Physical. Reacts with water to form o-phthalic acid (Kollig, 1993; Windholz et al., 1983). Based on an observed rate constant of 7.9 x 10-9/sec, the hydrolysis half-life is 88 sec (Hawkins, 1975).
Pyrolysis of phthalic anhydride in the presence of polyvinyl chloride at 600 °C for 10 min gave the following compounds: biphenyl, fluorene, benzophenone, 9-fluorenone, o-terphenyl, 9-phenylfluorene, and three unidentified compounds (Bove and Dalven, 1984).

Shipping

UN2214 Phthalic anhydride with>.05 % maleic anhydride, Hazard class: 8; Labels: 8-Corrosive material.

Purification Methods

Distil the anhydride under reduced pressure. Purify it from the acid by extracting with hot CHCl3, filtering and evaporating. The residue is crystallised from CHCl3, CCl4 or *benzene, or sublimed. Fractionally crystallise it from its melt. Dry it under vacuum at 100o. [Saltiel J Am Chem Soc 108 2674 1986, Beilstein 17/11 V 253.]

Precursor to dyestuffs

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 parachloro phenol followed by hydrolysis of the chloride.

Preparation of phthalate esters

As with other anhydrides, the alcoholysis reaction is the basis of the manufacture of phthalate esters, which are widely used (and controversial - see endocrine disruptor) plasticizers. In the 1980s, approximately 6.5×109 kg of these esters were produced annually, and the scale of production was increasing each year, all from phthalic anhydride. The process begins with the reaction of phthalic anhydride with alcohols, giving the monoesters:
C6H4(CO)2O + ROH → C6H4(CO2H)CO2R
The second esterification is more difficult and requires removal of water:
C6H4(CO2H)CO2R + ROHC6H4(CO2R)2 + H2O
The most important di ester is bis (2-ethyl hexyl) phthalate ("DEHP"), used in the manufacture of polyvinyl chloride.

Incompatibilities

Dust forms an explosive mixture with air. Phthalic anhydride reacts exothermically with water. The reactions are sometimes slow, but can become violent when local heating accelerates their rate. Acids accelerate the reaction with water. Incompatible with acids, strong oxidizing agents, alcohols, amines, and bases. Converted to phthalic acid in hot water. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides. caustics, ammonia, amines, water. Reacts violently with copper oxide or sodium nitrite 1 heat.

Waste Disposal

Use a licensed professional waste disposal service to dispose of this material. Dissolve or mix the material with a combustible solvent and burn in a chemical incinerator equipped with an afterburner and scrubber. All federal, state, and local environmental regulations must be observed. Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal.

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