Synthesis And Characterization Of Schiff Bases Based On Acylcarbazole

Carbazole?CZ?is a nitrogen-containing aromatic heterocyclic compound.It has strong capability of electronic migration,which is easy to form a relatively stable positive ions,with excellent hole transport capacity,good thermal oxidation stability,photochemical stability and so on.Schiff base is a kind of compound containing C=N bond structure which can emit fluorescence.Such compounds are widely used in sensors,fluorescent materials,dyes and drugs.A series of Schiff bases containing carbazolyl compounds were designed and synthesized.Effective addition of acylcarbazole and thiadoxazole?oxadiazole?,to get compounds which can be used as luminescent material.?1?The acyl carbazole were synthesized and characterized by FT-IR and 1H NMR.First,9-alkylcarbazole was synthesized by carbazole as raw material,then acyl carbazole was synthesized by Vilsmeier-Haack acylation reaction and Friedel-Crafts acylation reaction.The effects of selection of acylation reagents and catalysts,the molar ratio of the raw materials,the amount of the AlCl3,the reaction time and temperature on the yield were investigated by single factor experiment,with the synthesis of 3-acetyl-9-ethylcarbazole as an example.The optimal reaction conditions were: the acylating agent was acetyl chloride,the catalyst was anhydrous AlCl3,the molar ratio of 9-ethylcarbazole,acetyl chloride and alchlor was 1:1.1:1.1,the reaction temperature was-5?,the reaction time was 2.0h,the yield was 89.9%.?2?Six kinds of 2-amino-5-substituted-1,3,4-thiadiazoles were synthesized and their structures were characterized by FT-IR and 1H NMR.The target product were synthesized by thiourea and three kinds of fatty acids?three kinds of aromatic acid?as raw material,36%HCl?98%H2SO4?was the catalyst and solvent.The effects of the molar ratio of the raw materials,the reaction time and temperature on the yield were investigated by single factor experiment,with the synthesis of 2-amino-5-phenyl-1,3,4-thiadiazole as an example.The optimal reaction conditions were: the catalyst was 98% H2SO4,n?thiosemicarbazide?: n?benzoic acid?was 1:1.2,the reaction time was 5.0h,the reaction temperature was 80?,the yield was 88.6%.?3?Six kinds of 2-amino-5-substituted-1,3,4-oxadiazoles were synthesized and their structures were characterized by FT-IR and 1H NMR.First,six kinds of aromatic aldehyde semicarbszone were synthesized by semicarbazide hydrochloride and six aromatic aldehydes as raw materials and anhydrous ethanol as solvent.The target product were synthesized by 6 kinds of aromatic aldehyde semicarbazide in the liquid bromine under the action of cyclization.The effects of the selection of solvent,the molar ratio of the raw materials,the reaction time and temperature on the yield were investigated by single factor experiment,with the synthesis of benzaldehyde semicarbszone as an example.The optimal reaction conditions were: the solvent was anhydrous ethanol,the molar ratio of benzaldehyde and semicarbazide hydrochloride was 1:1.2,the reaction time was 3.0h,and the reaction temperature was 80?,the yield was 87.8%..The effects of the molar ratio of the raw materials,the reaction time,temperature and catalyst dosage on the yield were investigated by single factor experiment,with the synthesis of 2-amino-5-phenyl-1,3,4-oxadiazole as an example.The optimal reaction conditions were: the molar ratio of anhydrous sodium acetate and benzaldehyde semicarbazide was 3:1,when the amount of benzaldehyde semicarbazide was 0.01 mol,the amount of catalyst was 0.012 mol,the reaction temperature was 25?,the reaction time was 6.0h,the yield was 88.3%..?4?Schiff bases containing carbazolyl were synthesized by liquid phase method and solid phase method using acylcarbazole and 2-amino-5-substituted-1,3,4-thiadiazole?oxadiazole?as raw materials,and characterized by FT-IR and 1H NMR,¹³ C NMR.By comparing the two synthetic methods,solid phase solvent-free,easy to operate,the product yield higher than the liquid phase.The synthesis of Schiff base from 3-acetyl-9-methylcarbazole and 2-amino-5-phenyl-1,3,4-thiadiazole as an example was carried out by the response surface design optimization conditions.The optimum process conditions were: the molar ratio of 2-amino-5-phenyl-1,3,4-thiadiazole and PTSA was 1:1.1,the reaction time was 0.5h,pH was 4,the yield was 88.2%.The effects of substituents on the UV spectra and fluorescence spectra of Schiff base were studied.It was found that the change of the 5-position substituent in 2-amino-5-substituted-1,3,4-thiadiazole?oxadiazole?had little effect on the UV spectrum of Schiff bases.The structure contained the CZ ring,p-?,the less number of of alkyl carbon atoms substituted at 9-position N,the better conjugation of the whole system and fluorescence.