{{chembox | verifiedrevid = 443885075 | ImageFile = Isoindol.svg | ImageClass = skin-invert-image | ImageSize = 150px | ImageName = Skeletal formula | ImageFile1 = Isoindole-3D-balls-2.png | ImageName1 = Ball-and-stick model | PIN=2''H''-Isoindole<ref>{{cite book |author=International Union of Pure and Applied Chemistry |date=2014 |title=Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 |publisher=The Royal Society of Chemistry |pages=213 |doi=10.1039/9781849733069 |isbn=978-0-85404-182-4}}</ref> | OtherNames= |Section1={{Chembox Identifiers | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 2282425 | InChI = 1/C8H7N/c1-2-4-8-6-9-5-7(8)3-1/h1-6,9H | InChIKey = VHMICKWLTGFITH-UHFFFAOYAW | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/C8H7N/c1-2-4-8-6-9-5-7(8)3-1/h1-6,9H | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = VHMICKWLTGFITH-UHFFFAOYSA-N | CASNo_Ref = {{cascite|correct|??}} | CASNo=270-68-8 | UNII_Ref = {{fdacite|correct|FDA}} | UNII = PR6T8TL5NT | PubChem=3013853 | ChEBI_Ref = {{ebicite|correct|EBI}} | ChEBI = 33179 | SMILES = c1cccc2c1c[nH]c2 }} |Section2={{Chembox Properties | Formula=C<sub>8</sub>H<sub>7</sub>N | MolarMass=117.15 g/mol | Appearance= | Density= | MeltingPt= | BoilingPt= | Solubility= }} |Section3={{Chembox Hazards | MainHazards= | FlashPt= | AutoignitionPt = }} }}

In organic chemistry and heterocyclic chemistry, '''isoindole''' consists of a benzene ring fused with pyrrole.<ref>{{ cite book | author = Gilchrist, T. L. | title = Heterocyclic Chemistry | year = 1987 | publisher = Longman | isbn = 0-582-01422-0 }}</ref> The compound is an isomer of indole. Its reduced form is isoindoline. The parent isoindole is a rarely encountered in the technical literature, but substituted derivatives are useful commercially and occur naturally. Isoindoles units occur in phthalocyanines, an important family of dyes. Some alkaloids containing isoindole have been isolated and characterized.<ref name= Heugebaert>Heugebaert, Thomas S. A.; Roman, Bart I.; Stevens, Christian V. "Synthesis of isoindoles and related iso-condensed heteroaromatic pyrroles" Chemical Society Reviews 2012, volume 41, pp. 5626-5640. {{doi|10.1039/c2cs35093a}}</ref><ref>See for example: {{Cite journal | last1 = Zhang | first1 = X. | last2 = Ye | first2 = W. | last3 = Zhao | first3 = S. | last4 = Che | first4 = C. T. | title = Isoquinoline and isoindole alkaloids from Menispermum dauricum | doi = 10.1016/j.phytochem.2003.12.004 | journal = Phytochemistry | volume = 65 | issue = 7 | pages = 929–932 | year = 2004 | pmid = 15081297 | pmc = }}</ref>

==Synthesis== The parent isoindole was prepared by flash vacuum pyrolysis of an N-substituted isoindoline.<ref>R. Bonnett and R. F. C. Brown "Isoindole" J. Chem. Soc., Chem. Commun., 1972, 393-395. {{doi|10.1039/C39720000393}}</ref> N-Substituted isoindoles, which are easier to handle, can be prepared by dehydration of isoindoline-N-oxides. They also arise by myriad other methods, e.g., starting from xylylene dibromide (C<sub>6</sub>H<sub>4</sub>(CH<sub>2</sub>Br)<sub>2</sub>).

==Structure and tautomerism of 2-H-isoindoles == Unlike indole, isoindoles exhibit noticeable alternation in the C-C bond lengths, which is consistent with their description as pyrrole derivatives fused to a butadiene.

In solution, the 2''H''-isoindole tautomer predominates. It resembles a pyrrole more than a simple imine.<ref>{{cite book | title = Handbook of Heterocyclic Chemistry |author1=Alan R. Katritzky |author2=Christopher A. Ramsden |author3=J. Joule |author4=Viktor V. Zhdankin | page = 133 | publisher = Elsevier | year = 2010}}</ref> The degree to which the 2''H'' predominates depends on the solvent, and can vary with the substituent in substituted isoindoles.<ref>{{cite book | title = Heterocyclic Chemistry |author1=John A. Joule |author2=Keith Mills | publisher = John Wiley & Sons | year = 2010 | page = 447}}</ref>

:class=skin-invert-image|thumb|left|400px|2''H''-Isoindole (right) is the predominant tautomer relative to 1''H''-isoindole (left){{clear left}}

N-Substituted isoindoles do not engage is tautomerism and are therefore simpler to study.

== Isoindole-1,3-diones and related derivatives== The commercially important phthalimide is an ''isoindole-1,3-dione'' with two carbonyl groups attached to the heterocyclic ring.<ref>{{cite book |last1=Radtke |first1=Volker |last2=Erk |first2=Peter |last3=Sens |first3=Benno |date=2009 |chapter=Isoindoline pigments |editor1-last=Faulkner |editor1-first=Edwin B. |editor2-last=Schwartz |editor2-first=Russell J. |title=High Performance Pigments |edition=2nd |publisher=Wiley-VCH |pages=221–241 |doi=10.1002/9783527626915.ch14 |isbn=978-3-527-62691-5}}</ref> <div class="skin-invert-image"><gallery caption="Illustrative Isoindoline Derivatives" widths="130px" heights="120px" > File:PY139.svg|Pigment yellow 139, a common high performance pigment. File:PY185.svg|Pigment yellow 185, a common high performance pigment. File:Copper phthalocyanine.svg|Copper phthalocyanine, one of the most pervasive synthetic pigments. </gallery></div>

== See also ==

* 1,3-Disubstituted Isoindolines. * Isoindene with nitrogen replaced by a methylene group.

== References == {{reflist}}

{{Simple aromatic rings}}

Category:Isoindoles Category:Simple aromatic rings