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Phthalic anhydride

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Phthalic anhydride Basic information
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
  • OdorCharacteristic choking odor
  • PH2 (6g/l, H2O, 20℃)
  • PH Range2 at 6 g/l at 20 °C
  • explosive limit1.7-10.5%(V)
  • Water Solubility 6 g/L (20 ºC)
  • Sensitive Moisture Sensitive
  • Merck 14,7372
  • BRN 118515
  • Henry's Law Constant6.29 at 20 °C (approximate - calculated from water solubility and vapor pressure)
  • Exposure limitsNIOSH 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 Reference85-44-9(CAS DataBase Reference)
  • NIST Chemistry ReferencePhthalic anhydride(85-44-9)
  • EPA Substance Registry SystemPhthalic anhydride (85-44-9)
Safety Information
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.
    Phthalic anhydride
    Phthalic anhydride is an important chemical intermediate in the plastics industry from which are derived numerous phthalate esters that function as plasticizers in synthetic resins. Phthalic anhydride itself is used as a monomer for synthetic resins such as glyptal, the alkyd resins, and the polyester resins.
    Phthalic anhydride is also used as a precursor of anthraquinone, phthalein, rhodamine, phthalocyanine, fluorescein, and xanthene dyes.
    Phthalic anhydride is used in the synthesis of primary amines, the agricultural fungicide phaltan, and thalidomide. Other reactions with phthalic anhydride yield phenolphthalein, benzoic acid, phthalylsulfathiazole (an intestinal antimicrobial agent), and orthophthalic acid.

  • Chemical PropertiesPhthalic Anhydride is moderately flammable, white solid (flake) or a clear, colorless, mobile liquid (molten) Characteristic, acrid, choking odor.
  • Chemical PropertiesPhthalic anhydride is very slightly soluble in H2O, soluble in alcohol, and slightly soluble in ether.
  • Physical propertiesColorless to pale cream crystals with a characteristic, choking odor. Moisture sensitive. Odor threshold concentration is 53 ppb (quoted, Amoore and Hautala, 1983).
  • UsesPhthalic 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.
    manufacture of phthaleins, phthalates, benzoic acid, synthetic indigo, artificial resins (glyptal).
    Intermediate for Plastizers, Paints, Dyes and Pigments, Polyester Resins.
  • UsesThe compound is a high-tonnage chemical and is widely used in a variety of industrial organic syntheses.
  • UsesPhthalic 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.
  • DefinitionChEBI: The cyclic dicarboxylic anhydride that is the anhydride of phthalic acid.
  • Synthesis Reference(s)The Journal of Organic Chemistry, 25, p. 616, 1960 DOI: 10.1021/jo01074a035
    Synthesis, p. 612, 1973
    Tetrahedron Letters, 20, p. 2301, 1979 DOI: 10.1016/S0040-4039(01)93957-7
  • General DescriptionA 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 ReactionsReacts, usually slowly with water to form phthalic acid and heat [Merck 11th ed. 1989]. The phthalic acid is somewhat soluble in water.
  • Reactivity ProfilePhthalic 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 HazardSolid irritates skin and eyes, causing coughing and sneezing. Liquid causes severe thermal burns.
  • Fire HazardCombustible 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 ApplicationsPhthalic 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 allergensPhthalic 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 ProfilePoison 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 SynthesisPhthalic 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.
  • Potential ExposurePhthalic 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 FateChemical/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).
  • ShippingUN2214 Phthalic anhydride with>.05 % maleic anhydride, Hazard class: 8; Labels: 8-Corrosive material.
  • Purification MethodsDistil 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 dyestuffsPhthalic 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 estersAs 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.
  • IncompatibilitiesDust 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 DisposalUse 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.
Phthalic anhydride Preparation Products And Raw materials
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