Improved Syntheses of Versatile Ruthenium Hydridocarbonyl Catalysts Containing Electron‐Rich Ancillary Ligands

Clean, high‐yield routes are established to the important catalyst chlorobis(tricyclohexylphosphine)ruthenium hydridocarbonyl [RuHCl(CO)(PCy₃)₂] 2 and its N‐heterocyclic carbene (NHC) derivatives RuHCl(CO)(NHC)(PCy₃) ( 3a : NHC=IMes; 3b , NHC=H₂IMes; IMes=1,3‐dimesitylimidazol‐2‐ylidene). These complexes are obtained by treating chlorotris(tricyclohexylphosphine)ruthenium hydridocarbonyl [RuHCl(CO)(PPh₃)₃] 1 with tricyclohexylphosphine [PCy₃], or with the appropriate NHC ligand, then PCy₃. Advantages over prior routes to these complexes lie in the high yields from a conveniently accessible precursor, the absence of by‐products that otherwise prove difficult to remove, and the short reaction times under experimentally convenient conditions.     

Catalytic Carbon‐Fluorine Bond Activation with Monocoordinated Nickel‐Carbene Complexes: Reduction of Fluoroarenes

Monocoordinate nickel/N‐heterocyclic carbene complexes reveal unexpected reactivity towards aryl fluorides. Defluorination reactions were efficiently performed with a β‐hydrogen‐containing alkoxide (3 equiv.) in the presence of 3 mol % of [1:1] Ni(0)/IMes⋅HCl catalyst (IMes=1,3‐dimesitylimidazol‐2‐ylidene).     

Selective Hydrogenation of 1,3‐Butadiene to 1‐Butene by Pd(0) Nanoparticles Embedded in Imidazolium Ionic Liquids

The reduction of Pd(acac)₂ (acac=acetylacetonate), dissolved in 1‐n‐butyl‐3‐methylimidazolium hexafluorophosphate (BMI⋅PF₆) or tetrafluoroborate (BMI⋅BF₄) ionic liquids, by molecular hydrogen (4 atm) at 75 °C affords stable, nanoscale Pd(0) particles with sizes of 4.9±0.8 nm. Inasmuch as 1,3‐butadiene is at least four times more soluble in the BMI⋅BF₄ than butenes, the selective partial hydrogenation could be performed by Pd(0) nanoparticles embedded in the ionic liquid. Thus, the isolated nanoparticles promote the hydrogenation of 1,3‐butadiene to butenes under solventless or multiphase conditions. Selectivities up to 97% in butenes were observed in the hydrogenation of 1,3‐butadiene by Pd(0) nanoparticles embedded in BMI⋅BF₄ under mild reaction conditions (40 °C and 4 atm of hydrogen at constant pressure). Selectivities up to 72% in 1‐butene were achieved at 99% 1,3‐butadiene conversion, 40 °C and 4 atm of constant pressure of hydrogen. The amounts of butane (fully hydrogenated 1,3‐butadiene) and cis‐2‐butene products are marginal and the butenes do not undergo isomerisation process, indicating that the soluble Pd(0) nanoparticles possess a pronounced surface‐like rather than homogeneous‐like catalytic properties.     

Comparison of Selective Gas Phase‐ and Liquid Phase Hydrogenation of (Cyclo‐)Alkadienes towards Cycloalkenes on Pd/Alumina Egg‐Shell Catalysts

The hydrogenation of dienes such as 1,3‐butadiene, cyclooctadiene, and of acetylenic hydrocarbons on Pd catalysts shows high reaction rates and consequently, a strong influence of mass transfer on the selectivity of the intermediate alkene or cycloalkene product. 100 % selectivity towards (cyclo)‐alkene hydrogenation is achieved for the gas phase when the Thiele modulus is , where L is the thickness of the active layer and D_eff is the effective diffusion coefficient of the diene. The interdependencies expressed by this formula were studied in detail using model catalysts with regular pores of uniform length and diameter and perpendicular to the surface. These catalysts were prepared by anodic oxidation of aluminium wires and immobilization of the active Pd. For the liquid phase procedure of selective hydrogenation, a reaction mass transfer model has been derived in order to compare the gas phase and liquid phase procedures, in particular with respect to the selectivity. The hydrogenation of 1,3‐cyclooctadiene and of 1,3‐butadiene were studied for both procedures employing the same catalyst. The rate of hydrogenation can be represented for both cases by the identical kinetic equation r₁ = k₁ c_H2. This result is interpreted by assuming that the access of hydrogen to the surface through the dense layer of adsorbed diene is the rate determining step.     

Synthesis and Characterization of N‐Heterocyclic Carbene Substituted Phosphine and Phosphite Rhodium Complexes and their Catalytic Properties in Hydrogenation Reactions

Mixed N‐heterocyclic carbene‐substituted phosphine and phosphite complexes of rhodium were prepared, starting from [Rh(COE)₂Cl]₂ (COE=cyclooctene) by addition of free N‐heterocyclic carbenes (NHC) and PR₃. All new complexes were characterized by spectroscopy. In addition, the structures of trans‐chloro(1,3‐dicyclohexylimidazol‐2‐ylidene)‐bis(triphenylphosphite)rhodium(I) ( 5 ), chloro‐trans‐bis(1,3‐dicyclohexylimidazol‐2‐ylidene) (triphenylphosphine)rhodium(I) ( 6 ), and chloro(η⁴‐1,5‐cyclooctadiene)(1,3‐di‐[(1R,2S,5R)‐2‐isopropyl‐5‐menthylcyclohex‐1‐yl]imidazol‐2‐ylidene)rhodium(I) ( 8 ) were determined by single crystal X‐ray analyses. The hydrogenation of cyclohexene using molecular hydrogen has been optimized for some N‐heterocyclic carbene‐substituted phosphine and phosphite rhodium complexes by variation of the reaction conditions.     

MOP‐Type Binaphthyl Phosphite and Diamidophosphite Ligands and Their Application in Catalytic Asymmetric Transformations

Monodentate phosphite and diamidophosphite ligands have been developed based on O‐methyl‐BINOL. These chiral ligands are easy to prepare from readily accessible phosphorylating reagents – (S_a or R_a)‐2‐chlorodinaphtho[2,1‐d:1′,2′‐f][1,3,2]dioxaphosphepine and (2R,5S)‐2‐chloro‐3‐phenyl‐1,3‐diaza‐2‐phosphabicyclo[3.3.0]octane. The new ligands have demonstrated excellent enantioselectivity in the palladium‐catalysed allylic substitution reactions of (E)‐1,3‐diphenylallyl acetate with sodium p‐toluenesulfinate (up to 99 % ee), pyrrolidine (up to 97 % ee), dipropylamine (up to 95 % ee) and dimethyl malonate (up to 99 % ee). In the palladium‐catalysed deracemization of ethyl (E)‐1,3‐diphenylallyl carbonate, up to 96 % enantioselectivity has been achieved. The diamidophosphite ligands have exhibited very good enantioselectivity in the Rh‐catalysed asymmetric hydrogenation of dimethyl itaconate (up to 90 % ee).     

Donor‐Stabilized Phosphenium Adducts as New Efficient and Immobilizing Ligands in Palladium‐Catalyzed Alkynylation and Platinum‐Catalyzed Hydrogenation in Ionic Liquids

The straightforward synthesis of a new donor‐stabilized phosphenium ligand 3d by addition of bromodifurylphosphine to 1,3‐dimethylimidazolium‐2‐carboxylate 1 is described. The obtained ligand exhibits a very strong π‐acceptor character, comparable to that of triphenyl phosphite [P(OPh)₃] or of tris‐halogenophosphines, with a ν_CO(A₁) at 2087 cm⁻¹ for its nickel tricarbonyl complex. This ligand, as well as the related 3a which was obtained from chlorodiphenylphosphine, were tested in palladium‐catalyzed aryl alkynylation and in the platinum‐catalyzed selective hydrogenation of chloronitrobenzenes, both in an ionic liquid phase. In C C bond cross‐coupling we observed that the increase of the π‐acceptor character in ligand 3d , due to the introduction of an additional electron‐withdrawing group, provides a very efficient catalyst in the alkynylation reaction of aryl bromides with phenylacetylene, including the deactivated 4‐bromoanisole or the sterically hindered 2‐bromonaphthalene. The catalytic activity decreases with recycling due to the sensitiveness of ligands to protonation in the ionic phase. Conversely, a multiple recycling of the metal/ligand system in non‐acidic media was achieved from platinum‐catalyzed hydrogenation of m‐chloronitrobenzene. The catalytic results obtained by employing the complex of platinum(II) chloride with 3a [trans‐PtCl₂( 3a )₂] in comparison with the non‐ionic related trans‐tris(triphenylphosphine)platinum dichloride [trans‐PtCl₂(PPh₃)₂] complex clearly indicate that the simultaneous existence of a strong π‐acceptor character and a positive charge within the ligand 3a significantly increases the life‐time of the platinum catalyst. The selectivity of the reaction is also improved by decreasing the undesirable formation of dehalogenation products. This cationic platinum complex trans‐PtCl₂( 3a )₂ is the first example of a highly selective catalyst for hydrogenation of chloronitroarenes immobilized in an ionic liquid phase. The system was recycled six times without noticeable metal leaching in the organic phase, and no loss of activity.     

Synthesis of Ruthenium Hydride Complexes Containing beta‐Aminophosphine Ligands Derived from Amino Acids and their use in the H2‐Hydrogenation of Ketones and Imines

The new complexes RuHCl(PPh₂CH₂CHRNH₂)₂ and RuHCl(PPh₂CH₂CHRNH₂)(R‐ binap), R=H (Pgly), R=Me [(R)‐Pala] were prepared by the substitution of the PPh₃ ligands in RuHCl(PPh₃)₃ or RuHCl(PPh₃)[(R)‐binap] with beta‐aminophosphines derived from amino acids. The complex trans‐RuHCl(Pgly)[(R)‐binap] has been characterized by X‐ray crystallography. The complex trans‐RuHCl[(S)‐Ppro]₂ where (S)‐Ppro is derived from proline was also prepared and characterized by X‐ray crystallography. These were used as catalyst precursors in the presence of a base (KOPr‐i or KOBu‐t) for the hydrogenation of various ketones and imines to the respective alcohols and amines with H₂ gas (1–11 atm) at room temperature. Acetophenone was hydrogenated to (S)‐1‐phenylethanol in low ee (up to 40%) when catalyzed by the enantiomerically pure complexes. These complexes are especially active in the hydrogenation of sterically congested and electronically deactivated ketones and imines and are selective for the hydrogenation of CO bonds over CC bonds.     

Study of hydrogen surface mobility and hydrogenation reactions over alumina-supported palladium catalysts

Alumina-supported Pd catalysts with different particle surface densities have been prepared using incipient wetness impregnation of aqueous solution of a palladium nitrite complex. Buta-1,3-diene and orthoxylene hydrogenation reactions were performed both in a batch and a fixed bed reactor. Hydrogen surface mobility was studied using H₂–D₂ isotopic exchange. The influence of (i) the particle surface density and (ii) the surface area of the support on the catalytic properties are discussed. The turnover frequency (TOF) of the but-1,3-diene hydrogenation was highly sensitive to the surface density of Pd particles (D_sp). Moreover, for a given surface density, TOF also depend on the nature of the alumina support. For a given support, modifications of the electronic properties of palladium can explain the increase of the reaction rate with D_sp while changes in the kinetics of hydrogen surface diffusion are proposed to explain the support effect.     

Diphenyl Carbonate Synthesis by Homogeneous Pd Electrocatalyst

Electrochemical carbonylation of phenol with CO to diphenyl carbonate (DPC) using Pd electrocatalyst was studied at P(CO) = 1 atm and room temperature. Electrochemical carbonylation was conducted by galvanostatic electrolysis at 1 mA in electrolyte solutions containing phenol, sodium phenoxide and CH₃CN. It was found that electrochemical carbonylation by Pd was promoted by using 1,3-dimesitylimidazol-2-ylidene (IMes) ligand of a N-heterocyclic carbene. The current efficiency of DPC increased more than 3.4 times using the IMes ligand. The maximum current efficiency of DPC formation was 45 %.     

Chiral 1,2,3,4‐Tetrahydro‐1‐naphthylamine‐Derived Phosphine‐Phosphoramidite Ligand (THNAPhos): Application in Highly Enantioselective Hydrogenations of Functionalized CC Bonds

We have recently reported a new chiral 1,2,3,4‐tetrahydro‐1‐naphthylamine‐derived phosphine‐phosphoramidite ligand, (R_c,R_a)‐THNAPhos, that is highly efficient in the rhodium‐catalyzed asymmetric hydrogenation of a broad range of α‐enol ester phosphonates. To further demonstrate the utility of THNAPhos in asymmetric hydrogenation, in this paper, we describe its new application in the asymmetric hydrogenation of α‐dehydroamino acid esters, enamides, dimethyl itaconate and α‐enamido phosphonates. The results disclosed that the Rh/(R_c,R_a)‐THNAPhos complex is highly effective for the enantioselective hydrogenation of these kinds of functionalized CC olefins, affording the corresponding hydrogenation product in excellent enantioselectivities (normally over 99% ee).     

Impact of Incorporating Substituents onto the P‐o‐Anisyl Groups of DiPAMP Ligand on the Rhodium(I)‐Catalyzed Asymmetric Hydrogenation of Olefins

The introduction of 1,2‐bis[(o‐anisyl)(phenyl)phosphino]ethane (DiPAMP) as a P‐stereogenic ligand for rhodium(I)‐catalyzed hydrogenation by Knowles et al. came after their evaluation of several diphosphines. However, no in‐depth study was carried out on incorporating various substituents on its P‐o‐anisyl groups. In this work, we have prepared a large series of enantiopure and closely related DiPAMP analogues possessing various substituents (MeO, TMS, t‐Bu, Ph, fused benzene ring) on the o‐anisyl rings. The new ligands were evaluated in rhodium‐catalyzed hydrogenation of several model substrates: methyl α‐acetamidoacrylate, methyl (Z)‐α‐acetamidocinnamate, methyl (Z)‐β‐acetamidocrotonate, dimethyl itaconate, and atropic acid. They displayed enhanced activities and increased enantioselectivities, particularly the P‐(2,3,4,5‐tetra‐MeO‐C₆H)‐substituted ligand (4MeBigFUS). Interestingly enough, 88% ee was obtained in the hydrogenation of atropic acid using the Rh‐(4MeBigFUS) catalyst under mild conditions (10 bar H₂, room temperature) versus 7% ee using Rh‐DiPAMP. Conversely, the ligand possessing P‐(2,6‐di‐MeO‐C₆H₃) groups proved to slow down considerably the hydrogenation. X‐Ray structures of their corresponding Rh complexes are presented and discussed.     

Synthesis and characterization of alternate copolymers constructed by 1,3‐bis(diphenylsilyl)‐2,2,4,4‐tetraphenylcyclodisilazane units with oligo‐dimethylsiloxane segments

1,3‐Dichloro‐1,1,3,3‐tetraphenyldisilazane (DCTPS) with 71.6% yield was synthesized by the reaction of hexaphenylcyclotrisilazane (HPCT) with Ph₂SiCl₂ catalyzed by dibutyltin dilaurate. A ring‐closure reaction of DCTPS was carried out with BuLi in xylene–hexane mixture solvent; 1,3‐bis(chlorodiphenylsilyl)‐2,2,4,4‐tetraphenyl‐cyclodisilazane (BcPTPC) with 73.2% yield was obtained. Hydrolysis of BcPTPC in ether–triethylamine solvent resulted in 71.9% yield of 1,3‐bis(diphenylhydroxysilyl)‐2,2,4,4‐tetraphenylcyclodisilazane (B_HPTPC). By condensation polymerization of B_HPTPC with α,ω‐bis(diethylamino)‐oligo‐dimethylsiloxane, a kind of alternate copolymer constructed by 1,3‐bis(diphenylsilyl)‐2,2,4,4‐tetraphenylcyclodisilazane units with oligo‐dimethylsiloxane segments [P(BPTPC‐alt‐ODMS)] was synthesized. BcPTPC, B_HPTPC as well as P(BPTPC‐alt‐ODMS) were characterized by ²⁹Si‐NMR spectra, FT‐IR spectra, and elemental analysis. DGA study shows that P(BPTPC‐alt‐ODMS)s are thermally stable. The thermal decomposition onsets of P(BPTPC‐alt‐ODMS)s are all above 520°C. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1484–1490, 2005     

Combination of Reaction and Separation in Heterogeneous Catalytic Hydrogenation of Ethylformate

Continuous hydrogenation reaction of ethyl benzoylformate was studied over a (–)‐cinchonidine (CD)‐modified Pt/Al₂O₃ catalyst. The catalyst showed a good stability, and high enantioselectivity was achieved in the fixed‐bed reactor. Chromatographic separation of (R)‐ and (S)‐ethyl mandelate originating from a post‐continuous hydrogenation reaction of ethyl benzoylformate over the (–)‐CD‐modified Pt/Al₂O₃ catalyst was investigated in the same reaction mixture. A commercial column filled with a chiral selector resin was chosen as a perspective preparative‐scale adsorbent. Since adsorption equilibrium isotherms were linear within the entire investigated range of concentrations, they were determined by pulse experiments for the isomers present in a post‐reaction mixture. Breakthrough curves were measured and described successfully by the dispersive plug‐flow model with linear driving force approximation.     

Carbon‐Carbon Double Bond versus Carbonyl Group Hydrogenation: Controlling the Intramolecular Selectivity with Polyaniline‐Supported Platinum Catalysts

The use of polyaniline (PANI) as catalyst support for heterogeneous catalysts and their application in chemical catalysis is hitherto rather poorly known. We report the successful synthesis of highly dispersed PANI‐supported platinum catalysts (particle sizes between 1.7 and 3.7 nm as revealed by transmission electron microscopy, TEM) choosing two different approaches, namely (i) deposition‐precipitation of H₂PtCl₆ onto polyaniline, suspended in basic medium (DP method) and, (ii) immobilization of a preformed nanoscale platinum colloid on polyaniline (sol‐method). The PANI‐supported platinum catalysts were applied in the selective hydrogenation of the α,β‐unsaturated aldehyde citral. In order to benchmark their catalytic performance, citral hydrogenation was also carried out by using platinum supported on the classical support materials silica (SiO₂), alumina (Al₂O₃), active carbon and graphite. The relations of the structural characteristics and surface state of the catalysts with respect to their hydrogenation properties have been probed by EXAFS and XPS. It is found that the DP method yields chemically prepared PtO₂ on polyaniline and, thus, produces a highly dispersed and immobilized Adams catalyst (in the β‐PtO₂ form) which is able to efficiently hydrogenate the conjugated CC bond of citral (selectivity to citronellal=87%), whereas reduction of the CO group occurs with polyaniline‐supported platinum (selectivity to geraniol/nerol=78%) prepared via the sol‐method. The complete reversal of the selectivity between the preferred hydrogenation of the conjugated CC or CO group is not only particularly useful for the selective hydrogenation of α,β‐unsaturated aldehydes but also unveils the great potential of conducting polymer‐supported precious metals in the field of hitherto barely investigated chemical catalysis.     

Highly Enantioselective Hydrogenation of Quinoline and Pyridine Derivatives with Iridium‐(P‐Phos) Catalyst

The use of a chiral iridium catalyst generated in situ from the (cyclooctadiene)iridium chloride dimer, [Ir(COD)Cl]₂, the P‐Phos ligand [4,4′‐bis(diphenylphosphino)‐2,2′,6,6′‐tetramethoxy‐3,3′‐bipyridine] and iodine (I₂) for the asymmetric hydrogenation of 2,6‐substituted quinolines and trisubstituted pyridines [2‐substituted 7,8‐dihydroquinolin‐5(6H)‐one derivatives] is reported. The catalyst worked efficiently to hydrogenate a series of quinoline derivatives to provide chiral 1,2,3,4‐tetrahydroquinolines in high yields and up to 96% ee. The hydrogenation was carried out at high S/C (substrate to catalyst) ratios of 2000–50000, reaching up to 4000 h⁻¹ TOF (turnover frequency) and up to 43000 TON (turnover number). The catalytic activity is found to be additive‐controlled. At low catalyst loadings, decreasing the amount of additive I₂ was necessary to maintain the good conversion. The same catalyst system could also enantioselectively hydrogenate trisubstituted pyridines, affording the chiral hexahydroquinolinone derivatives in nearly quantitative yields and up to 99% ee. Interestingly, increasing the amount of I₂ favored high reactivity and enantioselectivity in this case. The high efficacy and enantioselectivity enable the present catalyst system of high practical potential.     

Synthesis and characterization of hyperbranched poly(silyl ester)s

Hyperbranched poly(silyl ester)s were synthesized via the A₂ + B₄ route by the polycondensation reaction. The solid poly(silyl ester) was obtained by the reaction of di‐tert‐butyl adipate and 1,3‐tetramethyl‐1,3‐bis‐β(methyl‐dicholorosilyl)ethyl disiloxane. The oligomers with tert‐butyl terminal groups were obtained via the A₂ + B₂ route by the reaction of 1,5‐dichloro‐1,1,5,5‐tetramethyl‐3,3‐diphenyl‐trisi1oxane with excess amount of di‐tert‐butyl adipate. The viscous fluid and soft solid poly(silyl ester)s were obtained by the reaction of the oligomers as big monomers with 1,3‐tetramethyl‐1,3‐bis‐β(methyl‐dicholorosilyl)ethyl disiloxane. The polymers were characterized by ¹H NMR, IR, and UV spectroscopies, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The ¹H NMR and IR analysis proved the existence of the branched structures in the polymers. The glass transition temperatures (T_g's) of the viscous fluid and soft solid polymers were below room temperature. The T_g of the solid poly(silyl ester) was not found below room temperature but a temperature for the transition in the liquid crystalline phase was found at 42°C. Thermal decomposition of the soft solid and solid poly(silyl ester)s started at about 130°C and for the others it started at about 200°C. The obtained hyperbranched polymers did not decompose completely at 700°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3430–3436, 2006     

Thiol‐Michael coupling and ring‐opening metathesis polymerization: facile access to functional exo‐7‐oxanorbornene dendron macromonomers

This paper describes the synthesis of the 2‐ and 4‐functional acrylic exo‐7‐oxanorbornene species 2‐((2‐((3aR,7aS)‐1,3‐dioxo‐1,3,3a,4,7,7a‐hexahydro‐2H‐4,7‐epoxyisoindol‐2‐yl)ethoxy) carbonyl)‐2‐methylpropane‐1,3‐diyl diacrylate and (((2‐((2‐((3aR,7aS)‐1,3‐dioxo‐1,3,3a,4,7,7a‐hexahydro‐2H‐4,7‐epoxyisoindol‐2‐yl)ethoxy) carbonyl)‐2‐methylpropane‐1,3‐diyl)bis(oxy))bis(carbonyl))bis(2‐methylpropane‐2,1,3‐triyl) tetraacrylate, and their use as common precursors for the preparation of a small library of dendronized thioether adducts via nucleophile‐mediated thiol‐Michael coupling chemistry. We subsequently demonstrate that the dendronized monomers can be (co)polymerized via ring‐opening metathesis polymerization employing Grubbs'‐type Ru‐based initiators to give novel functional dendronized (co)polymers of predictable molecular weights and acceptable dispersities (?_M = _w/ _n). © 2013 Society of Chemical Industry     

Syndio‐ and Isoselective Coordinative Chain Transfer Polymerization of Styrene Promoted by ansa‐Lanthanidocene/ Dialkylmagnesium Systems

Combinations of the discrete neutral allyl ansa‐lanthanidocenes {Me₂C(Cp)(Flu)}Nd[1,3‐ (SiMe₃)₂C₃H₃] and rac‐{Me₂C(Ind)₂}Y[1,3‐ (SiMe₃)₂C₃H₃] with di(n‐butyl)magnesium constitute efficient binary catalytic systems for the stereocontrolled coordinative chain transfer polymerization of styrene, yielding near‐perfect syndio‐ and isospecific polystyrenes, respectively, with high activities and productivities. By adjusting the amount of di(n‐butyl)magnesium, up to 200 polymer chains can be generated per lanthabide center, and good control of the molecular weight features enables the tailoring of low to medium molecular weight polymers.     

Destruction of chlorinated organics by hydrotreatment using Ru/TiO2 catalyst

Catalytic hydrodechlorination reactions of p‐chloro‐m‐cresol (PCMC) and p‐chloroaniline (PCA) were investigated in a slurry reactor using a Ru/TiO₂ catalyst. The organic reaction intermediates, m‐cresol and aniline, were further converted into methylcyclohexanol and cyclohexylamine respectively. Kinetics of PCMC hydrogenation was studied over the ranges in temperature, 323–373 K, H₂ partial pressure, 0.34–1.38 MPa, PCMC concentration, 3.5–14 mM and catalyst loading, 0.1–2 kg/m³. The reaction orders with respect to PCMC and H₂ were evaluated as 0.5 and 0.8 respectively. It was found that aniline hydrogenation is the rate‐determining step in the hydrotreatment of PCA. Kinetics of aniline hydrogenation was studied at 343 and 363 K over the ranges in H₂ partial pressure, 0.34–1.38 MPa, aniline concentration, 5.4–21.5 mM and catalyst loading, 0.1–0.6 kg/m³. The reaction orders with respect to aniline and H₂ were found to be 1.3 and 1.0 respectively. © 2012 Canadian Society for Chemical Engineering