Hydrodechlorination of para-substituted chlorobenzenes over a ruthenium/carbon catalyst

Solvent effects in the catalytic hydrotreament of haloaromatics over Pd/Al2O3 in water+organic mixtures

“…The results are presented in Table 2, where the following order of increasing (R HDH ) 0 is established: 4-CPo2-CPo3-CP. There is now some consensus in the literature that HDH proceeds via electrophilic hydrogen scission of the C-X bond with the formation of a cationic intermediate (Hagh and Allen, 1990), which is dissociatively adsorbed forming a s-complex through the carbon atom bearing the highest electron density (Murthy et al, 2005;Yoneda et al, 2008). Serguchev and Belokopytov (2001), taking selected chlorobenzenes, calculated the electron densities at each carbon and demonstrated that the values were greater in the presence of ring substituents that were located meta-with respect to each other.…”

“…Catalytic hydrodehalogenation (HDH) has now emerged as a viable approach to the treatment of toxic halogenated waste (Keane, 2005;Kovalchuk and d'Itri, 2004), where halogen removal in aromatic systems has been found to be dependent on the nature (Hara et al, 2008;Yoneda et al, 2008), number (Ding et al, 2008;Kim et al, 2008) and position (Chae and Buchwald, 2004;Shin and Keane, 1999a) of the halogen substituent(s). The scission of C-Cl (Aramendía et al, 1999a;Coq et al, 1986Coq et al, , 1995Díaz et al, 2008;Kim et al, 2008;Zinovyev et al, 2004;Zinovyev et al, 2005) and C-Br (Aramendía et al, 1999b;Fakhfakh et al, 2001;Liu et al, 2006;Wang et al, 2007;Yang et al, 2008) bonds has now been promoted using Fe (Fakhfakh et al, 2001;Kim et al, 2008), Ni Zinovyev et al, 2005), Pt (Díaz et al, 2008;Wang et al, 2007) and Pd (Aramendia et al, 1999a, b;Coq et al, 1986Coq et al, , 1995Yang et al, 2008;Zinovyev et al, 2004) catalysts, where the latter has been demonstrated to be the most efficient in terms of specific rate and resistance to deactivation (Centi, 2001;Urbano and Marinas, 2001).…”

Liquid phase hydrodechlorination of chlorophenols at lower temperature on a novel Pd catalyst

“…In a result, both C-Cl bonds at ortho-and para-position of hydroxyl on ring would be exposed to the attack of hydrogen at the meantime and a mixture of 2-CP and 4-CP would be formed. Here, we assume the dissociative adsorption of chlorophenols via the -complex of C-Cl bond at 4 position (not 2 position because of the steric hindrance due to the proximity of Cl substituent to hydroxyl on aromatic ring) with the edge and corner Pd atoms on Pd/MSCN, where the aromatic ring is possibly in tilted configuration as reported [26,27], resulting in the very low selectivity of 4-CP during the HDC. Therefore, only one reaction for HDC of 2,4-DCP is possible, namely the dechlorination of the C-Cl first at 4 position and then at 2 position.…”

Hydrodechlorination of Chlorobenzene Over Ni2P/SiO2 Catalysts: Influence of Ni2P Loading

“…As a promising method for disposing of chlorinated compound pollutant [22], catalytic hydrodechlorination (HDC) has been widely investigated over metal catalysts [23][24][25][26][27][28][29][30]. However, a fatal drawback of metal catalysts is deactivation due to HCl poison.…”