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slight yellow-green to white powder

Potassium phthalimide is usually used as organocatalyst for the cyanosilylation of various carbonyl compounds under extremely mild conditions,and also used as reagent for the transformation of allyl- and alkyl halides into protected primary amines.

General procedure for the synthesis of phthalimide potassium salt from 3-hydroxy-1H-isoindol-1-one: Add phthalimide to the reactor with 3 times the mass of anhydrous ethanol, and heat it up to 60℃. A pre-prepared anhydrous ethanol solution of 30% potassium methanolate (molar ratio of potassium methanolate to phthalimide 1.2:1) was slowly added by dropping through a burette with a controlled dropping time of 3 hours, during which the temperature was slightly elevated (up to a maximum of 65 °C). After the reaction lasted for 10 hours, the reaction mixture was filtered, washed once with anhydrous ethanol, and dried to give a high-purity potassium salt of phthalimide with a purity of 99.3% and a molar yield of 98%.

The solid may contain phthalimide and K2CO3 from hydrolysis. If too much hydrolysis has occurred (this can be checked by extraction with cold Me2CO in which the salt is insoluble, evaporate the Me2CO and weigh the residue), it would be better to prepare it afresh. If little hydrolysis has occurred, then recrystallise it from a large volume of EtOH, and wash the solid with a little Me2CO and dry it in a continuous vacuum to constant weight. [Salzerg & Supriawski Org Synth Coll Vol I 119 1941, Raman & IR: Hase J Mol Struct 48 33 1978, Dykman Chem Ind (London) 40 1972, IR, NMR: Assef et al. Bull Soc Chim Fr II 167 1979, Beilstein 21/10 V 270.]

[1] Patent: CN104447497, 2017, B. Location in patent: Paragraph 0018-0019; 0021; 0023
[2] Patent: CN106699682, 2017, A. Location in patent: Paragraph 0051; 0052
[3] Patent: CN107382980, 2017, A. Location in patent: Paragraph 0027; 0028; 0029; 0030
[4] Patent: CN107540647, 2018, A. Location in patent: Paragraph 0020-0024
[5] Journal of the American Chemical Society, 2011, vol. 133, # 41, p. 16410 - 16413