SECONDARY AMINES PLAY A VERY IMPORTANT ROLE IN TODAY?S CHEMICAL INDUSTRY OWING TO THEIR EXTENSIVE APPLICATIONS IN AGRICULTURAL, PHARMACEUTICAL, TEXTILE, POLYMER AND IN PERSONAL CARE FIELDS [1] UNFORTUNATELY, MOST OF THE AMINE SYNTHESIS PROCESSES AT THE INDUSTRIAL LEVEL ARE FOSSIL-BASED AND IMPLY ECONOMIC AND ENVIRONMENTAL PROBLEMS. HOWEVER, THE HETEROGENEOUSLY CATALYZED REDUCTIVE AMINATION OF LIGNIN-DERIVED PHENOLICS HAS BEEN RECOGNIZED AS AN EFFICIENT AND ECOFRIENDLY METHOD FOR THE SYNTHESIS OF PRIMARY OR HIGHER ORDER AMINES [2]. IN THIS SENSE, METAL-SUPPORTED CATALYSTS, SPECIFICALLY PALLADIUM, AND RHODIUM-BASED MATERIALS, HAVE DEMONSTRATED THEIR EFFECTIVITY TO PRODUCE SECONDARY AMINES [3,4]. THEREFORE, THERE IS A CRESCENT INTEREST IN EVALUATING THEIR ROLES WITHIN THE REACTION MECHANISMS BY TESTING DIFFERENT REACTION CONDITIONS AND PHENOLICS SOURCES NEVERTHELESS, THERE IS A LACK OF EXPERIMENTAL DATA ALLOWING TO ESTABLISH A CORRELATION BETWEEN THE NATURE OF THE METALLIC CLUSTERS, THE OPERATIONAL PARAMETERS, AND STERIC EFFECTS OF ALKYL-PHENOLICS WITH THE ACTIVITY AND SELECTIVITY TO AMINES. ACCORDINGLY, THIS DATASET INCLUDES RELIABLE EXPERIMENTAL MEASUREMENTS ON THE USE OF PD/C AND RH/C AS CATALYSTS FOR ........

CATALYTIC AMINATION OF CYCLOHEXANONE WITH ANILINE IS A SUSTAINABLE METHOD FOR PRODUCING SECONDARY AMINES. IN THIS PAPER, THE FULL CHARACTERIZATION OF THE CATALYST (RH/C) IS REPORTED. MOREOVER, A REACTION PATHWAY DESCRIBING THE CATALYTIC CYCLE HAS BEEN INCLUDED AND VALIDATED WITH EXPERIMENTAL OBSERVATIONS INTEGRATED INTO DELPLOT ANALYSIS. FINALLY, A KINETIC MODEL BASED ON LANGMUIR-HINSHELWOOD FORMALISM WAS ELUCIDATED AND VALIDATED. BIOMASS-BASED AMINES HAVE RECEIVED A LOT OF ATTENTION DUE TO THEIR SUSTAINABILITY AND CARBON ECONOMY. HEREIN, THE ROLES OF THE METAL SITES (RH0 OR PD0) AND OPERATING CONDITIONS ON THE KINETICS AND REACTION PATHWAYS OF THE HETEROGENEOUS CATALYTIC AMINATION OF CYCLOHEXANONE WITH ANILINE HAVE BEEN DISCUSSED. RH/C PROVIDES SECONDARY AMINES WITH REMARKABLE SELECTIVITY TOWARD THE HYDROGENATION PRODUCT (?SI=72?%). THE HYDROGENATION RATE OVER RH0 IS 1.5-FOLD HIGHER THAN THAT OBSERVED OVER PD0, WHILE ITS DEHYDROGENATION CAPACITY DIMINISHED (RD_RH ¡=0.74?H?1 AND RD_PD=1.32?H?1). THIS DIFFERENCE IN THE HYDROGENATION/DEHYDROGENATION PERFORMANCE ALLOWS CONTROL OVER THE SELECTIVITY VIA DISPROPORTIONATION OF AN IMINE INTERMEDIATE. THE KINETIC OBSERVATIONS CAN BE REPRESENTED USING THE LANGMUIR-HINSHELWOOD MODEL, INDICATING THAT THE FORMATION OF THE AMINAL INTERMEDIATE IS THE RATE-LIMITING STEP. THE APPARENT ACTIVATION ENERGY FOR THIS STEP ON RH/C (55?KJ/MOL) WAS HIGHER THAN THAT PREVIOUSLY REPORTED FOR PD/C (48?KJ/MOL).

THE VALIDATION OF PROTOCOLS FOR CARRYING OUT THE EXPERIMENTAL ANALYSIS OF AMINATION REACTIONS IS OF PARAMOUNT IMPORTANCE TO ENHANCE THE SCIENTIFIC KNOWLEDGE AND REPRODUCIBILITY OF RESULTS. ACCORDINGLY, IN THE PRESENT PAPER, A PROTOCOL HAS BEEN PROPOSED FOR THE STUDY OF THE AMINATION OF CYCLOHEXANONE-TO-SECONDARY AMINES (DIPHENYLAMINE AND N-CYCLOHEXYLANILINE) OVER HETEROGENEOUS CATALYSTS. THE RESULTS OF ACTIVITY AND SELECTIVITY, AND THE ELUCIDATION OF A PLAUSIBLE REACTION PATHWAY WERE DESCRIBED IN A PARENT PAPER. THEREFORE, THE PURPOSE OF THIS DOCUMENT IS TO INFORM ABOUT THE DETAILS OF THE EXPERIMENTAL SETUPS, THE METHODS, AND THE ANALYTICAL TECHNIQUES TO IDENTIFY AND QUANTIFY THE REACTION PRODUCTS. FINALLY, SOME PRACTICAL AND SAFETY CONSIDERATIONS ARE ALSO INCLUDED. ? ONE-POT CATALYTIC AMINATION OF CYCLOHEXANONE WITH ANILINE WAS PERFORMED EFFICIENTLY IN LIQUID PHASE ON PD/C. ? STIRRING, HE ATMOSPHERE AND TEMPERATURE CONTROL WERE CRITICAL TO ACHIEVE REPRODUCIBLE ACTIVITY RESULTS. ? ULTRA-HIGH PERFORMANCE LIQUID CHROMATOGRAPHY ALLOWS IDENTIFYING PRODUCTS AND REACTION INTERMEDIATES, WHILE NONANE PERFORMED WELL AS INTERNAL STANDARD FOR GC-FID QUANTIFICATION.

PRODUCING BIOMASS-DERIVED CHEMICALS TO SUBSTITUTE THEIR PETROCHEMICAL COUNTERPARTS HAS LONG BEEN AN ASPIRATION OF THE GREEN CHEMISTRY RESEARCH COMMUNITY. HOWEVER, SYNTHESIZING SECONDARY AMINES FROM BIOMASS PRECURSORS PRESENTS SEVERAL CHALLENGES RELATED TO CATALYST NATURE AND THE MECHANISTIC UNDERSTANDING OF REACTION SYSTEMS. HERE, WE UNRAVEL THE MECHANISTIC AND KINETIC IMPLICATIONS OF THE REDUCTIVE AMINATION OF PHENOL WITH CYCLOHEXYLAMINE OVER PD/C AND RH/C. A COMPETITIVE LANGMUIR-HINSHELWOOD REACTION MODEL WELL INTERPRETED THE KINETIC DATA, SUGGESTING THAT SUPPORT-METAL INTERFACES SERVE AS ACTIVE SITES FOR H2, ?NH2 AND ?NH ACTIVATION. THE APPARENT ACTIVATION ENERGIES FOR IMINE HYDROGENATION WERE 87.6 KJ MOL?1 (PD/C) AND 34.5 KJ MOL?1 (RH/C), WHILE HADS AND SADS VALUES CONFIRMED THE PHYSICOCHEMICAL CONSISTENCY OF THE MODEL. MOREOVER, THE CATALYSTS DEMONSTRATED THEIR HIGH STABILITY TO OPERATE FOR SEVERAL CATALYTIC CYCLES, WITH MINOR ACTIVITY LOSSES DUE TO METAL LEACHING AND PARTIAL SINTERING OF PD NANOPARTICLES. DESPITE PHENOL REDUCTIVE AMINATION FOLLOWING SIMILAR MECHANISMS ON RH/C AND PD/C, THEY SHOW DIFFERENCES IN SELECTIVITY BECAUSE THE HYDROGENATION OF IMINE IS MORE EFFICIENT ON RH0 THAN ON PD0. THIS IS THE FIRST MECHANISM-ORIENTED KINETIC STUDY FOR PHENOL REDUCTIVE AMINATION; THUS, IT PROVIDES VALUABLE INFORMATION FOR PROCESS DESIGN AND SCALE-UP.

THE LIQUID PHASE AMINATION OF THE CYCLOHEXANONE (CYO) WITH ANILINE (PHNH2) WAS STUDIED ON A PD/C CATALYST USING NACO2H AS A H-DONOR. CATALYTIC TESTS WERE PERFORMED IN BATCH REACTORS BY VARYING REACTANT CONCENTRATIONS (0, 0.1, 0.2 AND 0.4 MOL/L), THE TEMPERATURE (80?160 °C) AND H2-EQUIVALENTS AVAILABILITY (0, 2 AND 4 H2-EQUIVALENTS WITH RESPECT TO CYO). THE RESULTS INDICATE THAT, THE USE OF NACO2H BARELY AFFECT THE REACTIVITY (MEASURED AS INITIAL REACTION RATE) WHILE IT DOES INFLUENCE THE SELECTIVITY TO SECONDARY AMINES. THIS EFFECT WAS ASCRIBED TO THE LIMITED EFFECTIVITY OF THE H2 TRANSFER, WHICH WAS CONTROLLED BY THE WATER FORMED AFTER THE CONDENSATION OF THE CYO WITH THE PHNH2, HYDROGEN SOLUBILITY IN TOLUENE, AND THE MASS TRANSFER FROM THE LIQUID TO THE CATALYST SURFACE. THE EXPERIMENTAL OBSERVATIONS WERE CONSISTENT WITH A MULTI-STEP MECHANISM CONSISTING IN: A FIRST STEP OF CONDENSATION OF THE KETONE AND THE AMINE TO FORM AN IMINE, FOLLOWED BY THE DISPROPORTIONATION OF THE IMINE INTO SECONDARY AMINES. THE KINETIC MEASUREMENTS AT INITIAL RATE CONDITIONS WERE WELL INTERPRETED BY A LANGMUIR HINSHELWOOD (L-H) KINETIC MODEL, WHICH SUGGEST THAT THE SURFACE REACTION TO FORM THE INTERMEDIARY IMINE IS THE RATE LIMITING STEP (R.L.S).

THE HETEROGENEOUSLY CATALYZED REDUCTIVE AMINATION OF PHENOLICS FROM LIGNIN IS CONSIDERED AN ATTRACTIVE SUSTAINABLE ROUTE FOR THE SYNTHESIS OF PRIMARY OR HIGH-ORDER AROMATIC AND ALIPHATIC AMINES. HERE, THE REDUCTIVE AMINATION OF PHENOL WITH CYCLOHEXYLAMINE WAS STUDIED, AND INSIGHTS INTO THE ROLE OF THE CATALYST SUPPORT, METAL NANOPARTICLE SIZES, AND ACIDIC PROPERTIES WERE PROVIDED. BULK AND SURFACE CHARACTERIZATION, IR EXPERIMENTS, AND KINETIC MEASUREMENTS WERE PERFORMED, AND THEIR RESULTS WERE CORRELATED WITH THE CATALYTIC PERFORMANCE AND THE CONTENT OF LEWIS ACID SITES (PD/AL2O3 > PD/C > PD/SIO2). THE LEWIS ACID SITES IN THE SUPPORT AND THOSE FORMED BY H2 SPILLOVER ASSISTED PHENOL HYDROGENATION AND C?N BOND ACTIVATION, ENHANCING THE FORMATION OF SECONDARY AMINES (SELECTIVITY >90%). THE PD COORDINATION IN THE PARTICLES STRONGLY AFFECTED THE CATALYTIC ACTIVITY, INDICATING THAT PHENOL AMINATION IS A STRUCTURE-SENSITIVE REACTION. THE TURNOVER FREQUENCY VS. DISPERSION PROFILES COMBINED WITH THE SITE DISTRIBUTIONS IN THE PD PARTICLES (EDGE, CORNER, AND TERRACES) INDICATE THAT LOW-COORDINATION SITES FAVOR PHENOL AMINATION, WHICH WAS CONFIRMED VIA DIFFUSE REFLECTANCE INFRARED SPECTROSCOPY WITH FOURIER TRANSFORM AND HIGH-RESOLUTION TRANSMISSION ELECTRON MICROSCOPY. THIS STUDY COULD CONTRIBUTE TO THE UPCYCLING OF FRESH AND RECYCLED LIGNIN FRACTIONS TO PRODUCE AROMATIC AND ALIPHATIC AMINES.