Phthalimide

Organic Compound

Not to be confused with Thalidomide.

Phthalimide

Names
Preferred IUPAC name

1H-Isoindole-1,3(2H)-dione

Other names

1,3-dioxoisoindoline
Phthalimidoyl (deprotonated)

Identifiers

CAS Number

* 85-41-6 Y

3D model (JSmol)

* Interactive image

ChEBI |

* CHEBI:38817 Y

ChEMBL |

* ChEMBL277294 Y

ChemSpider |

* 6550 Y

ECHA InfoCard | 100.001.458

PubChem CID

* 6809

UNII |

* 1J6PQ7YI80 Y

CompTox Dashboard (EPA)

* DTXSID3026514

InChI

* InChI=1S/C8H5NO2/c10-7-5-3-1-2-4-6(5)8(11)9-7/h1-4H,(H,9,10,11) Y

Key: XKJCHHZQLQNZHY-UHFFFAOYSA-N Y

* InChI=1/C8H5NO2/c10-7-5-3-1-2-4-6(5)8(11)9-7/h1-4H,(H,9,10,11)

Key: XKJCHHZQLQNZHY-UHFFFAOYAS

SMILES

* O=C2c1ccccc1C(=O)N2

Properties[1]

Chemical formula

| C8H5NO2
Molar mass | 147.133 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

Magnetic susceptibility (χ)

| −78.4×10−6 cm3/mol
Related compounds

Related Amides

| Maleimide

Related compounds

| Phthalic anhydride

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Y verify (what is YN ?)

Infobox references

Chemical compound

Phthalimide is the organic compound with the formula C6H4(CO)2NH. 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.[2]

## Preparation[edit]

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.[2]

## Uses[edit]

Phthalimide is used as a precursor to anthranilic acid, a precursor to azo dyes and saccharin.[2]

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".[3] Alkyl halides can be converted to the N-alkylphthalimide:

C6H4(CO)2NH + RX + NaOH → C6H4(CO)2NR + NaX + H2O

The amine is commonly liberated using hydrazine:

C6H4(CO)2NR + N2H4 → C6H4(CO)2N2H2 \+ RNH2

Dimethylamine can also be used.[4]

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

## Reactivity[edit]

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 °C or with potassium hydroxide in absolute ethanol,[5] is used in the Gabriel synthesis of primary amines, such as glycine.

## Natural occurrence[edit]

Kladnoite is a natural mineral analog of phthalimide.[6] It is very rarely found among a few burning coal fire sites.

## Safety[edit]

Phthalimide has low acute toxicity with LD50 (rat, oral) of greater than 5,000 mg/kg.[2]

## References[edit]

1. ^ "Phthalimide". Chemicalland21. Retrieved 15 November 2011.
2. ^ a b c d Lorz, Peter M.; Towae, Friedrich K.; Enke, Walter; Jäckh, Rudolf; Bhargava, Naresh; Hillesheim, Wolfgang. "Phthalic Acid and Derivatives". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a20_181.pub2.
3. ^ "Phthalimides". Retrieved 2013-02-07.
4. ^ "Deprotection – removal of amine protecting groups (phthalimide and dimethylaminosulphonyl)". Archived from the original on 2014-12-03. Retrieved 2013-02-07.
5. ^ Salzberg, P. L.; Supniewski, J. V. "β-Bromoethylphthalimide". Organic Syntheses. 7: 8. doi:10.15227/orgsyn.007.0008.; Collective Volume, vol. 1, p. 119
6. ^ "Kladnoite". mindat.org. Retrieved 15 November 2011.

### General reading[edit]

* 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. Vol. 1 (6th ed.). London: Longman. ISBN 0-582-44221-4.

*[CID]: Compound ID
*[EPA]: U.S. Environmental Protection Agency