Phthalimide

Phthalimide

Phthalimide powder
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
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

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.

Uses

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

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". 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

Alkyl amines can also be used.

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

Reactivity

The high acidity of the imido N-H is the result of the pair of flanking electron-withdrawing carbonyl groups. Both sodium phthalimide and potassium phthalimide are well known. The latter can be made by reaction of phthalimide with potassium carbonate or potassium hydroxide.. The potassium salt is used in the Gabriel synthesis of primary amines.

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.

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

Natural occurrence

Kladnoite is a natural mineral analog of phthalimide. 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 mg/kg.

References

General reading