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Green route to fluorobenzene
Current processes for making fluoroaromatic compounds produce large amounts of waste. Now, a new cost-effective synthetic route to fluorinated aromatics that gives water as its only by-product has been discovered at Co. Passing benzene vapor over copper(II) fluoride at elevated temperatures gives fluorobenzene with 95% selectivity, according to authors. At 450 °C, 5% of the benzene is converted to fluorobenzene; at 550 °C, the conversion increases to about 30%. The CuF2 is reduced to copper metal during the reaction, X-ray powder diffraction studies show. Passing a stream of HF and O2 over the metal, however, gives H2O and regenerates CuF2. The cycle can be repeated without losing activity during the fluorination step, the researchers report. The process also can be used to make fluorotoluenes and difluorobenzenes, they note.
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