{{Short description|Organic compound}} {{distinguish|Thalidomide}} {{Chembox | Watchedfields = changed | verifiedrevid = 464205909 | Name = Phthalimide | ImageFile1_Ref = {{chemboximage|correct|??}} | ImageFile1 = Phthalimide.svg | ImageSize1 = 150 | ImageName1 = skeletal formula of the phthalimide molecule | ImageFile2 = Phthalimide-3D-balls.png | ImageSize2 = 170 | ImageName2 = ball-and-stick model of the phthalimide molecule | ImageFile3 = phthalimide.jpg | ImageCaption3 = Phthalimide Powder | PIN = 1''H''-Isoindole-1,3(2''H'')-dione | OtherNames = 1,3-dioxoisoindoline<br />Phthalimidoyl (deprotonated) |Section1={{Chembox Identifiers | ChEBI_Ref = {{ebicite|correct|EBI}} | ChEBI = 38817 | SMILES = O=C2c1ccccc1C(=O)N2 | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 6550 | PubChem = 6809 | InChI = 1/C8H5NO2/c10-7-5-3-1-2-4-6(5)8(11)9-7/h1-4H,(H,9,10,11) | InChIKey = XKJCHHZQLQNZHY-UHFFFAOYAS | ChEMBL_Ref = {{ebicite|correct|EBI}} | ChEMBL = 277294 | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/C8H5NO2/c10-7-5-3-1-2-4-6(5)8(11)9-7/h1-4H,(H,9,10,11) | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = XKJCHHZQLQNZHY-UHFFFAOYSA-N | CASNo_Ref = {{cascite|correct|CAS}} | CASNo = 85-41-6 | UNII_Ref = {{fdacite|correct|FDA}} | UNII = 1J6PQ7YI80 | RTECS = }} |Section2={{Chembox Properties | Properties_ref = <ref>{{cite web |url= http://www.chemicalland21.com/specialtychem/finechem/PHTHALIMIDE.htm|title= Phthalimide|publisher= Chemicalland21|accessdate= 15 November 2011}}</ref> | C=8 | H=5 | O=2 | N=1 | Appearance = White solid | Density = | Solubility = <0.1 g/100 ml (19.5&nbsp;°C) | MeltingPtC = 238 | BoilingPtC = 336 | BoilingPt_notes = sublimes | pKa = 8.3 | pKb = 5.7 | Viscosity = | MagSus = {{val|-78.4|e=-6|u=cm<sup>3</sup>/mol}} }} |Section3={{Chembox Structure | MolShape = | Coordination = | CrystalStruct = | Dipole = }} |Section7={{Chembox Hazards | ExternalSDS = | MainHazards = | FlashPt = | HPhrases = | PPhrases = | GHS_ref = }} |Section8={{Chembox Related | OtherFunction_label = Amides | OtherFunction = Maleimide | OtherCompounds = Phthalic anhydride }} }}

'''Phthalimide''' is the organic compound with the formula C<sub>6</sub>H<sub>4</sub>(CO)<sub>2</sub>NH. It is the imide derivative of phthalic anhydride. It is a sublimable white solid that is slightly soluble in water but more so upon addition of base. It is used as a precursor to other organic compounds as a masked source of ammonia.<ref name=Ullmanns>{{Ullmann | first1 = Peter M. | last1 = Lorz | first2 = Friedrich K. | last2 = Towae | first3 = Walter | last3 = Enke | first4 = Rudolf | last4 = Jäckh | first5 = Naresh | last5 = Bhargava | first6 = Wolfgang | last6 = Hillesheim | title = Phthalic Acid and Derivatives | doi = 10.1002/14356007.a20_181.pub2}}</ref>

== Uses == :[[image:Folpet.png|thumb|160px|Folpet, a phthalimide, is a commercial fungicide.<ref>{{cite book |doi=10.1002/0471238961.0621140704180509.a01 |chapter=Fungicides, Agricultural |title=Kirk-Othmer Encyclopedia of Chemical Technology |date=2000 |last1=Dreikorn |first1=Barry A. |last2=Owen |first2=W. John |isbn=978-0-471-48494-3 }}</ref>|left]]

Phthalimide is used as a precursor to anthranilic acid, a precursor to azo dyes and saccharin.<ref name=Ullmanns/>

Alkyl phthalimides are useful precursors to amines in chemical synthesis, especially in peptide synthesis where they are used "to block both hydrogens and avoid racemization of the substrates".<ref name='ochem'>{{cite web | url = https://www.organic-chemistry.org/protectivegroups/amino/phthalimides.htm | title = Phthalimides | accessdate = 2013-02-07}}</ref> Alkyl halides can be converted to the N-alkylphthalimide: : C<sub>6</sub>H<sub>4</sub>(CO)<sub>2</sub>NH + RX + NaOH → C<sub>6</sub>H<sub>4</sub>(CO)<sub>2</sub>NR + NaX + H<sub>2</sub>O The amine is commonly liberated using hydrazine: : C<sub>6</sub>H<sub>4</sub>(CO)<sub>2</sub>NR + N<sub>2</sub>H<sub>4</sub> → C<sub>6</sub>H<sub>4</sub>(CO)<sub>2</sub>N<sub>2</sub>H<sub>2</sub> + RNH<sub>2</sub>

Dimethylamine can also be used.<ref name='removal'>{{cite web | url = http://scientificupdate.co.uk/process-chemistry-information/item/deprotection-removal-of-amine-protecting-groups-phthalimide-and-dimethylaminosulphonyl.html | title = Deprotection – removal of amine protecting groups (phthalimide and dimethylaminosulphonyl) | accessdate = 2013-02-07 | url-status = dead | archiveurl = https://archive.today/20141203032450/http://scientificupdate.co.uk/process-chemistry-information/item/deprotection-removal-of-amine-protecting-groups-phthalimide-and-dimethylaminosulphonyl.html | archivedate = 2014-12-03 }}</ref>

Some examples of phthalimide drugs include thalidomide, amphotalide, taltrimide, talmetoprim, and apremilast. With a trichloromethylthio substituent, a phthalimide-derived fungicide is Folpet.

== Reactivity == It forms salts upon treatment with bases such as sodium hydroxide. The high acidity of the imido N-H is the result of the pair of flanking electrophilic carbonyl groups. Potassium phthalimide, made by reacting phthalimide with potassium carbonate in water at 100&nbsp;°C or with potassium hydroxide in absolute ethanol,<ref>{{OrgSynth|id=cv1p0119|title=β-Bromoethylphthalimide|first1=P. L.|last1=Salzberg|first2=J. V.|last2=Supniewski|date=1927|volume=7|page=8|collvol=1|collvolpages=119|doi=10.15227/orgsyn.007.0008}}</ref> is used in the Gabriel synthesis of primary amines, such as glycine.

== Preparation == Phthalimide can be prepared by heating phthalic anhydride with alcoholic ammonia giving 95–97% yield. Alternatively, it may be prepared by treating the anhydride with ammonium carbonate or urea. It can also be produced by ammoxidation of ''o''-xylene.<ref name="Ullmanns" />

:thumb|left|280px|Synthesis of phthalimide from phthalic anhydride{{clear-left}}

Phthalimide can also be prepared from phthalic acid by the following process:

:thumb|left|300px|Synthesis of phthalimide from phthalic acid{{clear-left}}

Carboxylic acids when reacted with ammonia give ammonium salts, which in turn give amides when strongly heated.

== Natural occurrence == Kladnoite is a natural mineral analog of phthalimide.<ref>{{cite web |url= http://www.mindat.org/min-2222.html|title= Kladnoite|publisher= mindat.org|accessdate= 15 November 2011}}</ref> It is very rarely found among a few burning coal fire sites.

==Safety== Phthalimide has low acute toxicity with {{LD50}} (rat, oral) of greater than 5,000&nbsp;mg/kg.<ref name=Ullmanns/>

== References == {{reflist|30em}}

===General reading=== {{refbegin|30em}} * {{cite book|last1= Vollhardt|first1= K. Peter C.|last2= Schore|first2= Neil Eric|authorlink2= Neil E. Schore|title= Organic Chemistry: Structure and Function|edition= 4th|year= 2002|publisher= W. H. Freeman|location= New York|isbn= 978-0-7167-4374-3|url-access= registration|url= https://archive.org/details/organicchemistry00voll_0}} * {{cite book |last1= Finar|first1= Ivor Lionel|title= Organic Chemistry|edition= 6th|volume= 1|year= 1973|publisher= Longman|location= London|isbn= 0-582-44221-4}} {{refend}}

Category:Phthalimides