Phthalimide

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Not to be confused with Thalidimide. ‹See Tfd›
Phthalimide
skeletal formula of the phthalimide molecule
ball-and-stick model of the phthalimide molecule
Identifiers
CAS number 85-41-6 YesY
PubChem 6809
ChemSpider 6550 YesY
ChEBI CHEBI:38817 YesY
ChEMBL CHEMBL277294 YesY
Jmol-3D images Image 1
Properties[1]
Molecular formula C8H5NO2
Molar mass 147.13 g mol−1
Appearance White solid
Melting point 238 °C (460 °F; 511 K)
Boiling point 336 °C (637 °F; 609 K) sublimes
Solubility in water <0.1 g/100 ml (19.5 °C)
Acidity (pKa) 8.3
Basicity (pKb) 5.7
Related compounds
Related Amides Maleimide
Related compounds Phthalic anhydride
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Phthalimide is an imide, which is a chemical compound with two carbonyl groups bound to a secondary amine or ammonia. It is a white solid at room temperature.

Preparation[edit]

Phthalimide can be prepared by heating phthalic anhydride with aqueous ammonia giving 95-97% yield. Alternatively, it may be prepared by fusing the anhydride with ammonium carbonate.

Uses[edit]

Phthalimide is used in plastics, in chemical synthesis, and in research. They are useful for protecting amines in chemical synthesis, especially in peptide synthesis where they are used " to block both hydrogens and avoid racemization of the substrates".[2] They are commonly removed with hydrazine, but dimethylamine can also be used.[3]

Reactivity[edit]

It forms salts with various metals such as potassium and sodium due to its high acidity caused by the electrophilic carbonyl groups attached to the nitrogen atom, which can be made by reacting phthalimide with metal carbonates. Potassium phthalimide, made by reacting phthalimide with potassium carbonate in water at 100 °C or with potassium hydroxide in absolute ethanol,[4] is used in the Gabriel synthesis of primary amines, and the Gabriel synthesis of glycine has yields as high as 85%.

Natural occurrence[edit]

Kladnoite is a natural mineral analog of phthalimide.[5] It is very rarely found among a few burning coal fire sites.

References[edit]

  1. ^ "Phthalimide". Chemicalland21. Retrieved 15 November 2011. 
  2. ^ "Phthalimides". Retrieved 2013-02-07. 
  3. ^ "DEPROTECTION – REMOVAL OF AMINE PROTECTING GROUPS (PHTHALIMIDE AND DIMETHYLAMINOSULPHONYL)". Retrieved 2013-02-07. 
  4. ^ "β-BROMOETHYLPHTHALIMIDE". Organic Syntheses. Retrieved 15 November 2011. 
  5. ^ "Kladnoite". mindat.org. Retrieved 15 November 2011. 
  • Vollhardt, K. Peter C.; Schore, Neil Eric (2002). Organic Chemistry: Structure and Function (4th ed.). New York: W.H. Freeman. ISBN 978-0-7167-4374-3. 
  • Finar, Ivor Lionel (1973). Organic Chemistry 1 (6th ed.). London: Longman. ISBN 0-582-44221-4.