Electrochemical Conversion of Dichloroacetic Acid to Chloroacetic Acid in Conventional Cell and in Two Microfluidic Reactors

Abstract

The electrochemical conversion of dichloroacetic acid to chloracetic\ud acid is investigated in conventional cells and in microreactors.\ud Two different microreactors are used: the first is\ud a filter press cell equipped with PTFE micrometric spacers, easy\ud to assemble and disassemble and available for a large variety\ud of electrodes and solvents; the second is made using an adhesive\ud spacer, micromilling and press and could easily be developed\ud on an industrial scale. The electrochemical synthesis is\ud performed successfully in the microreactors equipped with\ud a graphite cathode under proper operative conditions. The\ud performance of the process strongly depends on the nature of\ud the cathode and, for microreactors, on flow rate and current\ud density. Both microreactors give high conversions and selectivity\ud under a single-pass mode and are allowed to work without\ud supporting electrolyte at low cell voltages

Electrochemical Conversion of Dichloroacetic Acid to Chloroacetic Acid in a Microfluidic Stack and in a Series of Microfluidic Reactors

“…Microfluidic reactorso ffer new appealing solutionsf or the electrosynthesis of fine chemicals [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] and the treatment of wastewatersc ontaminated by recalcitrant pollutants. [22][23][24][25] Thus, microfluidic devices, with very small distances between electrodes, can offer several important advantages such as: * Possibility to operate without supporting electrolytes at low cell potentials.…”

“…[22,23] Several kinds of microfluidic devices have been proposed in literature. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] Most of them rely on microfluidic channels but it is essential to recognize that only one dimension perpendicular to the flow is sufficient to achieve laminar flows. Thus, parallel plates separated by micrometricd istances using spacers bring together the sought microfluidic properties, the large volumetric flows of interesta nd decrease the energetic constraintso np umpsw hen this is required.…”

“…Thus, parallel plates separated by micrometricd istances using spacers bring together the sought microfluidic properties, the large volumetric flows of interesta nd decrease the energetic constraintso np umpsw hen this is required. Quite recently,w e have reported the construction and application of two different microfluidic devices to the electrosynthesis of chloroacetic acid in water [21] through cathodic reduction of dichloroacetic acid. Chloroacetic acid, an important reagent for severalchemical reactions, is industrially synthesized mainly by chlorination of acetic acid which gives rise to the formation of relevant amountso fd ichloroacetic acid and to as mall extent of trichloroacetic acid.…”

“…[21,[27][28][29] It has been shown that using microfluidic reactors equipped with compact graphite cathodes, chloroacetic acid can be obtained at low cell potentials in water with high conversionsa nd selectivity under as ingle-pass mode without added supporting electrolyte. [21] These proof-of-concept experiments involved quite small electrode surfacea reas (4 cm 2 in most cases), thus limiting the productivity of the microreactor and the final concentration of the product.…”

“…[21,[27][28][29] It has been shown that using microfluidic reactors equipped with compact graphite cathodes, chloroacetic acid can be obtained at low cell potentials in water with high conversionsa nd selectivity under as ingle-pass mode without added supporting electrolyte. [21] These proof-of-concept experiments involved quite small electrode surfacea reas (4 cm 2 in most cases), thus limiting the productivity of the microreactor and the final concentration of the product. In fact, this is ageneral issue since most of the studies reported in the literature on the electrosynthesis of fine chemicals in microreactors exhibit quite low productivities [9] as ar esult of low electrode surfaces and small flow rates.…”