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ChemicalBook CAS DataBase List 1,8-NAPHTHOSULTAM

1,8-NAPHTHOSULTAM synthesis

3synthesis methods
-

Yield:603-72-5 70%

Reaction Conditions:

with trichlorophosphate at 130; for 3 h;

Steps:

5.3. 1,2-Dihydro-1λ6-naphtho[1,8-cd]isothiazole-1,1-dione 6

Five grams of the potassium salt of 1,8 naphthyl amine sulphonic acid were pulverized and placed in a flask containing three times that weight of POCl3. After attaching a reflux condenser the whole was heated in an oil bath to 130 °C. At 100 °C the offensive vapors of hydrochloric acid are given off and must be led into flue. To hasten the reaction the flask is shaken repeatedly. After the irritating vapors have ceased to be given off the heating is continued until the contents of the flask ceases to form a dyestuff when diazotized and developed. As a rule the reaction is complete after 3 h. The removal of the excess POCl3 requires some care because of the mud like consistency of the contents of the flask. Finally the contents of the flask are poured into ice bath. The grey product is filtered off by means of a suction pump and greater part of the phosphoric acid removed by repeated washing. The crude product was recrystallised from benzene after through drying. Mp 175-180 °C; 1H NMR (DMSO, 300 MHz): δ 8.62 (d, 1H, J = 8.0 Hz), 8.12 (d, 1H, J = 8.0 Hz), 7.75-7.74 (m, 1H), 7.61 (d, 1H, J = 8.0 Hz), 7.32 (dd, 1H, J = 7.5, 6.7 Hz), 6.90 (d, 1H, J = 6.8 Hz), 5.36 (s, 1H); MS (EI): m/z 206 (M++H).

References:

Kamal, Ahmed;Ramakrishna;Lakshma Nayak;Raju;Subba Rao;Viswanath;Vishnuvardhan;Ramakrishna, Sistla;Srinivas [Bioorganic and Medicinal Chemistry,2012,vol. 20,# 2,p. 789 - 800] Location in patent:experimental part