Hydrogenation of halonitrobenzenes is the way to produce halogenated anilines that are important reagents for the manufacture of a wide variety of drugs, pesticides, pigments, and dyes. However, the production of halogenated anilines is accompanied by a complication, their easy hydrodehalogenation, which results in the formation of undesirable by-products. This issue generates serious technological problems and increases production costs associated with the separation and purification of the final product. Therefore, much effort is directed to working out a system of possibly the lowest or even zero hydrodehalogention activity, which would produce chloroanilines with a 100% yield.[1] One of the solutions proposed involves the use of untypical supports such SnO2,[2] g-Fe2O3,[3] g-ZrP,[4] and MgF2.[5] Many promising results achieved by us in the case of the Ru/MgF2 [5] catalyst have prompted attempts at improving selectivity by admixing ruthenium with copper. Copper, as a group Ib element, preferentially occupies edges, corners, and other low coordination metal sites on the catalyst surface,[6] thus changing the catalyst structure. As hydrogenolysis of the carbon-halogen bond is a structure-sensitive reaction, it is very likely that such a change can result in the increase of selectivity of chloronitrobenzene reduction to chloroaniline. Our study was inspired by papers published by Sinfelt et al.[7] in 1970s, who have shown that the addition of copper to groupVIII metal decreases hydrogenolysis activity markedly, but its effect on other reactions such as hydrogenation [7b] is much smaller. Although bimetallic RuÀCu catalysts have been known for many years, their use in the hydrogenation of chloronitrobenzene has, to our knowledge, not been reported before. A support of the active phase was magnesium fluoride, which is a mesoporous material of the surface area of 50 m2 gÀ1. Synthesis of the porous MgF2 is very easy and cheap, with Mg (CO3) 2 and 40% aqueous solution of hydrofluoric acid as substrates. Monometallic ruthenium and copper catalysts were produced by the traditional and simple method of the support impregnation with aqueous solutions of ruthenium (III) chloride and copper (II) nitrate, respectively, whereas the bimetallic catalysts were prepared by co-impregnation. After the evaporation of water, the catalysts were dried and reduced in an H2 atmosphere. Parameters characterizing the catalysts are given in Table 1. The data presented in Table 1 will be discussed later in relation to the catalytic data. Hydrogenation of ortho-chloronitrobenzene (o-CNB) to ortho-chloroaniline (o-CAN) was performed in a liquid-phase at

808C. In the same conditions the reaction was performed using o-CAN as a substrate, to evaluate the hydrodechlorination activity of the catalysts. Results of the catalytic studies are given in Figure 1. The analysis of Figure 1 reveals that the rate of hydrogenation of o-CNB nitro group is almost independent of the amount of copper introduced to the catalyst and comparable with that reported in the literature for ruthenium catalysts.[2, 8] In the case of monometallic Ru1 (1) catalyst, the selectivity to o-CAN was 98%. The only side product was aniline (AN). Small admixture of copper to the ruthenium catalyst