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Skeletal formula
Space-filling model
IUPAC name
1,2-dicyanobenzene, phthalonitrile
Other names
phthalodinitrile, 1,2-benzenedicarbonitrile
CAS number 91-15-6 YesY
ChemSpider 6775 YesY
Jmol-3D images Image
PubChem 7042
Molar mass 128.13 g/mol
Appearance Off-white crystals with lumps on the surface.
Odor Almond-like
Density 4.42[1]
Melting point 139 to 141 °C (282 to 286 °F; 412 to 414 K)
Boiling point sublimes
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Phthalonitrile is an organic compound with the formula C6H4(CN)2, which is an off-white crystal solid at room temperature. It is a benzene derivative, containing two adjacent nitrile groups. The compound is partially soluble in water, and is soluble in acetone, nitrobenzene, and benzonitrile. The molecule is used as a precursor to phthalocyanine pigments, fluorescent brighteners, and photographic sensitizers.

History of synthesis[edit]

The first formation of phthalonitrile was reported in 1896 by Johannes Pinnow. It was noted to be a byproduct of the reaction between orthamidobenzonitrile hydrochloride, sodium nitrite, and hydrochloric acid to synthesize orthodicyanodiazoamidobenzene.[2] The first intentional method derived for the synthesis of phthalonitrile appeared in 1907, when phthalamide was boiled with acetic anhydride. While initial yields were small, it was a precursor that eventually to the contemporary large-scale synthesis seen today.[3]

Contemporary synthesis[edit]

In a single-stage continuous process, phthalonitrile is prepared by the ammoxidation of o-xylene in the presence of a vanadium oxide-antimony-oxide catalyst over heat (480 °C). This process passes a gaseous mixture of o-xylene, ammonia, and oxygen through a distributor plate into a fluidized bed reactor, containing the catalyst.[4]

Synthesis of phthalonitrile

Another method of producing phthalonitrile is the Rosenmund von Braun reaction in which an ortho substituted dihalobenzene is reacted with copper(I) cyanide, which results in the halide groups being replaced by cyano groups.[5]


The phthalocyanine pigment, which is a normative precursor to the blue dye in jeans, is generated through the mixing of a metal, a metal halide, or a metal alkoxide in solution with C6H4(CN)2. The reaction is carried out in a solvent at around 180 °C.[6]

Synthesis of a metallo phthalocyanine

Polymers of phthalonitrile have been developed for use in high temperature composite applications, and have attractive properties including a glass transition temperature exceeding 450 °C, fire performance that meets MIL-STD-2031, and absence of volatile production during the curing process.[7]


  1. ^ CDC - NIOSH Pocket Guide to Chemical Hazards
  2. ^ Pinnow, Johannes; Samann, C. Derivatives of Orthamidobenzonitrile. Berichte der Deutschen Chemischen Gesellschaft (1896), 29 623-32. CODEN: BDCGAS CAN 0:88468 AN 1906:88468 CAPLUS.
  3. ^ Braun, A.; Tscherniac, J. Products of the Action of Acetic Anhydride on Phthalamide. Berichte der Deutschen Chemischen Gesellschaft (1907), 40 2709-14. CODEN: BDCGAS ISSN:0365-9496. CAN 1:10790 AN 1907:10790 CAPLUS
  4. ^ Lorz, Peter M. Phthalic Acid and Derivatives. Ulmanns Encyclopedia of Industrial Chemistry. Wiley-VCH: Weinheim, 2002. doi:10.1002/14356007.a20_181.pub2.
  5. ^ Karl M. Kadish, Kevin M. Smith, Roger Guilard. The Porphyrin Handbook. 2003.
  6. ^ Löbbert, Gerd. Phthalocyanines. Ullmann’s Encyclopedia of Industrial Chemistry. Published online: 15 June 2000. doi:10.1002/14356007.a20_213.
  7. ^ "Are high temperature thermoset resins ready to go commercial?". Composites World. 11 January 2004.