Synthesis Of Novel Carbazole Derivatives

Carbazole derivatives are widely used to synthesize dyes, pesticides, medicines and resins. Furthermore, carbazole derivatives have been used as non-linear optical material since their excellent optical properties. Carbazole derivatives bearing 1,3,4-oxadiazole, 1,3,4-thiadiazole and thiourea moieties may be good active compounds or optical materials with high fluorescent quantum yields and laser quantum yields.In this thesis, four series of carbazole derivatives were first synthesized using carbazole as starting material.This thesis includes five chapters:Chapter one: The advance of carbazole derivatives in synthesis, properties and applications.This part were reviewed the advance of new carbazole derivatives and their properties and applications.Chapter two: Microwave assisted syntheses of 2-aryl-5-(9'-ethylcarbazol -3'-yl)-1,3,4-oxadiazolesA novel intermediate 1-( 9 -ethyl-9H-carbazole-3 -methylene)-2-aroylhydrazines were prepared by the acid hydrazide and 9-ethyl-3-carbaldehyde under solvent-free condition and micromve irradiation. The intermediate reacted with potassium permanganate in N,N-dimethylformamide under microwave irradiation to form a new family of 1,3,4-oxadiazoles. This synthetic strategy has features of short reaction period, high yield and simple work-up procedure. Furthermore, this eco-friendly strategy efficiently avoids the use of extremely toxic dehydration reagents.Chapter three: Synthesis of 2-arylamino-5-(9'-ethylcarbazol-3'-yl)-l,3,4-thiadiazolesN-substituted 9-ethylcarbazol-3-carbaldehyde thiosemicarbazones were first synthesized by the reactions of 9-ethylcarbazol-3-carbaldehyde with various 4-arylthiosemicarbazides in high yield. The 2-arylamino-5-(9'-ethylcarbazol-3'-yl)-1,3,4-thiadiazoles were also obtainted successfully by the cyclization of the novel intermediate N-substituted 9-ethylcarbazol-3-carbaldehyde with MnO₂ at room temperature. This method has advantages of mild reaction condition, high yield and simple work-up procedure.Chapter four: Synthesis of Novel Carbazole-based DithioureasA series of novel carbazole-based dithioureas were efficiently synthesized by reactions of 9-ethyl-3,6-diaminocarbazole with various aroyl isothiocyanates at room temperature under catalyst-free condition in high yield.Chapter five: Synthesis of Carbazole Based DithiosemicarbazonesA series of novel carbazole based dithiosemicarbazones were efficiently synthesized by reactions of 3,6-diacetyl-9-ethylcarbazole with various 4-arylthiosemicarbazides in high yield.The structures of all the compounds were conformed by elemental analyses, IR and ¹H NMR.