3D model (JSmol)
|Molar mass||147.13 g·mol−1|
|Melting point||238 °C (460 °F; 511 K)|
|Boiling point||336 °C (637 °F; 609 K) sublimes|
|<0.1 g/100 ml (19.5 °C)|
|×10−6 cm3/mol −78.4|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
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.
Phthalimide can be prepared by heating phthalic anhydride with aqueous 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.
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
Dimethylamine can also be used.
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, is used in the Gabriel synthesis of primary amines, such as glycine.
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