Preparation of 2-bromofluorenone by Liquid-phase Oxidation

2-Bromofluorene is a nonintrusive end-capping reagent to control molecular weights and to generate well-defined oligomers [1]. 2-Bromofluorene 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. It’s carcinogenic effects on humans are currently being investigated [2].

Here, we introduced an invention for preparing 2-bromofluorenone by liquid-phase oxidation. The invention belongs to the field of fine chemical engineering, and particularly relates to a method for preparing 2-bromofluorenone by liquid-phase oxidation. The method comprises the following steps: dissolving 2-bromofluorene in N, N-dimethylformamide, adding a catalyst, stirring at 30-40 DEG C under normal pressure, carrying out air oxidation, reacting for 2-4 hours, distilling, filtering, washing with water, and drying to obtain the 2-bromofluorenone. The yield is 96%, and the purity is 99-99.5%. The weight ratio of the 2-bromofluorene to the N, N-dimethylformamide is 1:(3.5-5); and the mole ratio of the 2-bromofluorene to the catalyst is 1:(0.03-0.5). The method has the advantages of mild reaction conditions, lower solvent consumption, high yield, low cost, small environmental pollution, recyclable solvent without further treatment after use and short reaction time, is simple to operate, and is very suitable for large-scale industrial production.

2-Bromofluorene is a nonintrusive end-capping reagent to control molecular weights and to generate well-defined oligomers [1]. 2-Bromofluorene 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. It’s carcinogenic effects on humans are currently being investigated [2].

Here, we introduced an invention for preparing 2-bromofluorenone by liquid-phase oxidation. The invention belongs to the field of fine chemical engineering, and particularly relates to a method for preparing 2-bromofluorenone by liquid-phase oxidation. The method comprises the following steps: dissolving 2-bromofluorene in N, N-dimethylformamide, adding a catalyst, stirring at 30-40 DEG C under normal pressure, carrying out air oxidation, reacting for 2-4 hours, distilling, filtering, washing with water, and drying to obtain the 2-bromofluorenone. The yield is 96%, and the purity is 99-99.5%. The weight ratio of the 2-bromofluorene to the N, N-dimethylformamide is 1:(3.5-5); and the mole ratio of the 2-bromofluorene to the catalyst is 1:(0.03-0.5). The method has the advantages of mild reaction conditions, lower solvent consumption, high yield, low cost, small environmental pollution, recyclable solvent without further treatment after use and short reaction time, is simple to operate, and is very suitable for large-scale industrial production.
 
The procedure are as follows: a mixture of 2-bromofluorene was dissolved in N, N- dimethylformamide, and then adding a catalyst, at 30-40 ° C, atmospheric pressure agitation, air oxidation, reaction of 2-4 hours, distillation, filtration, washed with water and dried to obtain 2-bromo-fluorenone; wherein, fluorene and 2-bromo-N, N- feeding-dimethylformamide weight ratio is 1: 2-5; 2_ bromofluorene with the catalyst The molar ratio is 1: 0.04-0.06. The catalyst is potassium hydroxide, sodium hydroxide, sodium alkoxide or quaternary amine base compound. The quaternary amine base is tetramethyl ammonium bromide, tetramethyl ammonium chloride, tetraethyl ammonium chloride or benzyl; the alcohol is a sodium compound as sodium methoxide or sodium ethoxide.

Further to say, the fluorene and 2-bromo-N, N- feed-dimethylformamide is the preferred weight ratio of 1: 3.5-5, and optimally 1: 3.5; 2_ bromofluorene hydroxide feed molar ratio of potassium is preferably 1: 0.03 to 0.5, optimally from 1: 0.05, the reaction temperature at 35-40 ° C [3].

Reference

[1] https://www.sigmaaldrich.com/catalog/product/aldrich/124060?lang=en&region=GB
[2] https://www.molbase.com/en/1133-80-8-moldata-28873.html#tabs
[3] https://patents.glgoo.top/patent/CN104030907A/en?q=+2-Bromofluorene