Method for synthesizing 3, 6-dibromo-9-bromophenyl-9H-carbazole

Abstract

The invention discloses a method for synthesizing 3, 6-dibromo-9-bromophenyl-9H-carbazole, and belongs to the technical field of chemistry. The synthesis method comprises the following steps: dissolving N-phenyl carbazole and a bromination reagent in an organic solvent at room temperature, performing stirring, adding an oxidant, performing reacting for 4-8 hours, recovering the solvent after the reaction is finished, performing extracting, desolventizing and recrystallizing an organic layer to obtain 3, 6-dibromo-9-bromophenyl-9H-carbazole, and controlling the temperature of the reaction system to be lower than the boiling point of the organic solvent. According to the preparation method, a one-step method is adopted at room temperature, commercially available N-phenylcarbazole is used asa raw material, under the action of a bromination reagent and an oxidizing agent, tribromo NPC can be obtained with high yield and high purity, and the method is mild and simple in condition, simple to operate, low in cost, high in yield and beneficial to industrial production of enterprises.

Description

technical field [0001] The invention relates to the technical field of chemistry, in particular to a method for synthesizing tribromo-N-phenylcarbazole by oxidative bromination of N-phenylcarbazole. Background technique [0002] Organic electrophosphorescent light-emitting devices (PhOLEDs), which are materials with a host-guest structure, have extremely high application potential in the fields of display and lighting. Carbazole has π-electron conjugated system, intramolecular electron transfer characteristics and lone pair electron heteroatoms, so carbazole and its derivatives have strong charge transport ability and photoelectric performance. A single carbazole molecule has poor photoelectric properties due to its weak conjugation system. Therefore, it is usually necessary to modify the carbazole site by bromination to realize the arylation / heteroarylation of the carbazole site, further expand the electronic conjugated system, and improve the charge transport ability. 3,...

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Problems solved by technology

[0008] Among the above-mentioned synthetic routes, the reaction of route I has a low yield and requires the use of pre-modified carbazole bromide, which increases the cost of the route; Environmental challenges; the third is that it needs to be reacted at high temperature (150°C) for a long time (24h), which may lead to dark color of the reaction solution and increase the difficulty of later purification

[0009] The route II one needs to use expensive p-bromoiodobenzene as the aryl source, which increases the reaction cost and is unfavorable for industrialized production; the second is to use N-bromosuccinimide (NBS) as the bromine source, which has poor atom economy, The by-product of succinimide will be produced, which increases the difficulty and cost of purification in the later stage; the third is that this reaction requires a two-step method, and the total yield is low, which makes the route economically poor

[0010] For another example, in 2012, "Heilongjiang Science" 2012, Volume 3, Phase 1, Page 26-27, Li Meng et al published an article entitled "Synthesis of 3-bromo-9-phenylcarbazole", which Describes the one-step preparation of monobrominated or dibrominated compounds using N-phenylcarbazole and brominating reagents as raw materials. However, using NBS as a bromine source will generate butanediimine as a by-product after bromination, and the product Coexistence increases the treatment cost of the three wastes; in addition, this system requires the use of mixed solvents, which increases the difficulty of subsequent solvent recovery and further increases the process cost

Due to the chemical identity of the 3 and 6 positions of carbazole, the excess bromine source can simultaneously brominate the 3 and 6 positions to obtain dibrominated products, but for the weak electrophilicity of the N-phenyl para position, the bromine produced by NBS dissociation Positive ions are difficult to further efficiently add to it to complete the bromination process

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