Phthalic anhydride

Chembox new
Name = Phthalic anhydride
ImageFile = Phthalic anhydride.png ImageSize = 100px
ImageName = Phthalic anhydride
ImageFile1 = Phthalic anhydride-3d.png ImageSize1 = 150px
IUPACName = 1,2-benzenedicarboxylic anhydride
OtherNames = Isobenzofuran-1,3-dione
Section1 = Chembox Identifiers
CASNo = 85-44-9
RTECS = TI3150000

Section2 = Chembox Properties
Formula = C8H4O3
MolarMass = 148.1 g/mol
Appearance = white Flakes
Density = 1.53 g/cm3, solid
Solubility = 0.62 g/100g reacts slowly
MeltingPt = 131 °C
BoilingPt = 295 °C "subl."

Section3 = Chembox Structure
CrystalStruct =
Dipole =

Section7 = Chembox Hazards
EUClass =
RPhrases = R22, R37/38, R41, R42/43
SPhrases = S2, S23, S24/25, S26, S37/39, S46
FlashPt = 152 °C

Section8 = Chembox Related
OtherCpds = Phthalic acid

Phthalic anhydride is the organic compound with the formula C6H4(CO)2O. This anhydride of phthalic acid, a colourless solid, is an important industrial chemical, especially for the large-scale production of plasticizers.

ynthesis and production

Phthalic anhydride was first reported in 1836 by 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 + 2CO2When separating the phthalic anhydride from byproducts such as o-xylene in water, or maleic anhydride, a series of switch condensers is required.

Applications in industry and organic synthesis

Phthalic anhydride is a versatile intermediate in organic chemistry, in part because it is bifunctional and cheaply available. Most characteristically, it undergoes hydrolysis and alcoholysis. Hydrolysis by hot water, forms "ortho"-phthalic acid. This process is reversible: phthalic anhydride re-forms upon heating the acid above 180 °C.cite book
last = Noller
first = Carl R.
title = Chemistry of Organic Compounds, 3rd ed.
publisher = W. B. Saunders
year = 1965
location = Philadelphia
pages = 602

Preparation of phthalate esters

The alcoholysis reaction is the basis of the manufacture of phthalate esters, which are widely used plasticizers. [Peter M. Lorz, Friedrich K. Towae, Walter Enke, Rudolf Jäckh, Naresh Bhargava, Wolfgang Hillesheim "Phthalic Acid and Derivatives" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH: Weinheim, 2002.] 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 gives the mixed esters::C6H4(CO)2O + ROH → C6H4(CO2H)CO2RThe second esterification is more difficult and requires removal of water::C6H4(CO2H)CO2R + ROH overrightarrow{leftarrow} C6H4(CO2R)2 + H2OThe most important diester is bis(2-ethylhexyl) phthalate ("DEHP"), used in the manufacture of polyvinyl chloride.

Organic 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. [OrgSynth | author = Joseph Kenyon | title = "d"- and "l"-Octanol-2| collvol = 1 | collvolpages = 418| year = 1941 | prep = CV1P0418] A related ring-opening reaction involves peroxides to give the useful peroxy acid: [OrgSynth | author = George B. Payne | title = Monoperphthalic acid| collvol = 5 | collvolpages = 805| year = 1973 | prep = CV5P0805] :C6H4(CO)2O + H2O2 → C6H4(CO3H)CO2H

When separating the phthalic anhydride from byproducts such as o-xylene in water, or maleic anhydride, a series of switch condensers is required, rather than a complicated setup of distillation columns that never converge in many industrial process simulation programs such as AspenTech.

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 para-chlorophenol followed by hydrolysis of the chloride. [OrgSynth | author = L. A. Bigelow and H. H. Reynolds | title = Quinizarin | collvol = 1 | collvolpages = 476| year = 1941 | prep = CV1P0476]


External links

* [ International Chemical Safety Card 0315]
* [ NIOSH Pocket Guide to Chemical Hazards]

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Look at other dictionaries:

  • phthalic anhydride — n a crystalline cyclic acid anhydride C8H4O3 that is used esp. in making alkyd resins and is a structural part of thalidomide * * * a reactive, low molecular weight compound with a wide variety of industrial uses, including the manufacture of… …   Medical dictionary

  • phthalic anhydride — n. a white, solid substance, C6H4 (CO) 2O, produced by the oxidation of naphthalene and used to make the phthalein dyes, certain synthetic resins, etc …   English World dictionary

  • phthalic anhydride — ftalio (rūgšties) anhidridas statusas T sritis chemija formulė C₆H₄:(CO)₂:O atitikmenys: angl. phthalic anhydride rus. фталевый ангидрид ryšiai: sinonimas – 1,3 izobenzfurandionas …   Chemijos terminų aiškinamasis žodynas

  • phthalic anhydride — noun The acid anhydride of phthalic acid; manufactured by the oxidation of xylene or naphthalene, widely used in the synthesis of dyes, insecticides, plasticizers and pharmaceuticals …   Wiktionary

  • phthalic anhydride — noun a white cyclic anhydride • Hypernyms: ↑anhydride …   Useful english dictionary

  • phthalic anhydride — noun Date: 1855 a crystalline cyclic acid anhydride C8H4O3 used especially in making alkyd resins …   New Collegiate Dictionary

  • phthalic anhydride — Chem. a white, crystalline, slightly water soluble solid, C8H4O3, used chiefly in the manufacture of dyes, alkyd resins, and plasticizers. [1850 55] * * * …   Universalium

  • phthalic anhydride — phthal′ic anhy′dride n. a white, crystalline, slightly water soluble solid, C8H4O3, used chiefly in the manufacture of dyes, alkyd resins, and plasticizers • Etymology: 1850–55 …   From formal English to slang

  • Phthalic acid — Phthalic acid …   Wikipedia

  • Anhydride phtalique — Représentations de l anhydride phtalique …   Wikipédia en Français

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