description
2-Bromofluorene is an isolated product of coal tar and its derivatives are used as important raw materials for fine chemicals. It is often used as synthetic intermediate of the OLED material in industry, by the reaction of barbier-type ultrasonic radiation, It is also used to study the conversion of aryl bromides to aryl triethoxy silane.
Lab Preparation Methods: propylene carbonate is used as solvent, N-bromosuccinimide (NBS) is used as brominated reagent to carry bromination reaction of fluorine, and this reaction can synthesize 2-bromofluorene and 2,7-dibromofluorene. By the investigation of reaction temperature, NBS amount, the adding methods, the optimal reaction conditions for the synthesis of 2-bromofluorene is confirmed. The optimal reaction conditions are: reaction temperature is 23℃, the molar ratio of NBS with fluorine is 1.1:1, NBS is added by stage addition. First fluorene and propylene carbonate is preheated to 60℃, so fluorine is all dissolved, and then it drops to the reaction temperature, NBS is added by stage addition. 2-bromofluorene and 2,7-dibromofluorene recrystallizes with ethanol and acetic acid respectively, the purity of target product of liquid chromatography can reach more than 99%.
Uses
(1) It can be used as pharmaceutical intermediate, it is also important intermediate in the synthesis of optoelectronic material.
(2) By ultrasonic radiation of Barbier-type reaction, 2-bromofluorene is used for the study of aryl bromide (aryl bromides) converts to aryl triethoxysilane (aryltriethoxysilanes). It is also for the preparation of N-carbazole fluorene oligomers end-capped. It can be used as intermediates of OLED materials in industry.
Chemical Properties
white to slightly yellow crystalline powder
Uses
2-Bromofluorene was used in the synthesis of end-capping reagent 2-bromo-9,9-di-
nhexylfluorene. It has been used in the preparation of poly(di-
n-hexylfluorene)s end capped with 2-bromofluorene, 2-bromo-9,9-di-
n-hexylfluorene and 9-bromoanthracene through Ni(0) mediated polymerization. It was also used in the synthesis of 2-bromo-9,9-dihexylfluorene.
Synthesis Reference(s)
Journal of the American Chemical Society, 80, p. 4327, 1958
DOI: 10.1021/ja01549a053
General Description
2-Bromofluorene is a nonintrusive end-capping reagent to control molecular weights and to generate well-defined oligomers. It is used as a reagent for the preparation of dibromofluorene-labelled polystyrene by nitroxide-mediated polymerization. It is also being used in the agricultural sector as a fungicide for tomato disease control. Its carcinogenic effects on humans are currently being investigated.
Synthesis
Example 6 Synthesis of 2-bromofluorene: N-bromosuccinimide (17.8 g, 0.1 mol) was added one time to a solution of fluorene (16.6 g, 0.1 mol) in propylidene carbonate (125 mL) at 60 °C. The reaction mixture was then cooled for 1 hour. Upon completion of the reaction, the mixture was diluted with water (2 L) to separate the solid product. The separated solid was dissolved in toluene (250 mL) and the toluene solution was washed with water. After concentration, the product was recrystallized by an ethanol-water system to give 23.3 g of 2-bromofluorene in 95% yield with a melting point of 95.6-101.3°C. Mass spectrometry analysis showed the molecular ion peaks (m/z): 322, 324, 326 (corresponds to M+ dibromo), 244, 246 (corresponds to M+).
References
[1] Bulletin of the Chemical Society of Japan, 1989, vol. 62, # 2, p. 439 - 443
[2] Patent: US6730793, 2004, B1. Location in patent: Page column 5
[3] Synlett, 2006, # 5, p. 737 - 740
[4] Journal of Materials Chemistry C, 2016, vol. 4, # 17, p. 3765 - 3773
[5] Patent: CN108530262, 2018, A. Location in patent: Paragraph 0021-0042
