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Dichloromethane is shown to be a useful solvent in catalytic hydrogenation reactions of easily reduced functional groups (alkenes, alkynes, imines, and nitroarenes) using palladium on carbon as the catalyst under mild conditions (ambient pressure and temperature). [ABSTRACT FROM AUTHOR]

The expanding global economy resulted mainly from consuming fossil fuels, which are scarce and cause prodigious environmental harm. Mankind is shifting towards sustainable, efficient and clean energy sources known as green energy. The storage of green energy is an urge of time, to fulfil the energy requirements. Supercapacitors are gaining popularity in the field of energy storage due to their excellent safety, cost-effectiveness, and environmental friendliness. The forthright strategy of using a nitrogen-rich phthalocyanine macrocycle as a nanosized particle is to increase surface area resulting in a high specific capacitance. Herein, an innovative approach has been made by synthesising nanosized hyperbranched metal-free/Co-Phthalocyanine characterized by various analytical and spectroscopic techniques. The morphology of the composite was confirmed through physicochemical characterization like BET, SEM, XRD and electrochemical features were studied through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). The electrode modification was carried out using the binder Poly (vinyl alcohol)-Tetraethyl orthosilicate (PVA-TEOS) crosslinked hybrid solution. The intercalated nanosized palladium on carbon matrix with HBCoPc and HBPc at different ratios enhanced the performance of capacitance. Amongst all the ratios, HBCoPc: Pd–C with 30:70 ratio has demonstrated superior specific capacitance of 824.25 F g−1 at 0.5 A g−1. Additionally, the fabricated electrode of HBCoPc: Pd–C and HBPc: Pd–C has exhibited good capacitance retention of 84.03 % and 81.01 % over 5000 cycles, respectively. This work delivers a promising approach towards the development of high-performance supercapacitors using metal phthalocyanine/metal-carbon composites as a new way to manufacture devices for conversion and energy storage. [Display omitted] • Syntheses and characterization of hyper-branched metal-free/cobalt (II) phthalocyanine. • Hybrid PVA-TEOS solution is used as a binder for entire electrochemical studies. • The composites of hyper-branched metal-free/cobalt (II) phthalocyanine and palladium on carbon matrix in different ratios are equipped for capacitance studies. • The specific capacitance of HBCoPc: Pd–C and HBPc: Pd–C are 824.25 and 355.82 F g−1, respectively. [ABSTRACT FROM AUTHOR]

A trickle bed reactor (TBR) was used to study different process parameters upon hydrogen peroxide direct synthesis. The catalysts used were commercial palladium on active carbon. The influence of pressure (1.75–25 barg), temperature (5–60°C), liquid flow rate (2–13.8 ml·min-1), gas flow rate (3.4–58.5 ml·min-1), catalyst amount (90–540 mg), Pd percentage on the support (5% wt., 10% wt. and 30% wt. Pd/C) as well as promoter concentrations (0.0005–0.001 m) were all varied as process parameters to better understand the behaviour of the system. By contrast, the gas phase molar composition of the feed (4:20:76=H2:O2:CO2) was kept constant. The strong influence between liquid flow rate, gas flow rate and catalyst amount were identified as the key parameters to tune the reaction, and related to the activity of the catalyst. In essence, these parameters must be carefully tuned to control the hydrogen consumption. The maximum productivity (289 μmol H2O2·min-1) and yield (83.8%) were obtained when a diluted bed of 30% Pd/C was applied. The H2O2 hydrogenation was studied in order to understand its role in the H2O2 direct synthesis reaction network. The hydrogenation reaction mechanism and the role of NaBr were identified thanks to the experiment proposed in the present work. Consequently, understanding the whole reaction mechanism from the process conditions studied led to a deeper understanding of all of the phenomena involved in the H2O2 direct synthesis.

An atom economical and catalytic route for the synthesis of aryl- and alkyl-substituted secondary amines has been developed. Using a bis(amidate)bis(amido)titanium(IV) precatalyst, the hydroamination of terminal alkynes with a range of amines results in the selective formation of the anti-Markovnikov product. The crude enamine/imine mixtures are effectively hydrogenated using palladium on carbon (Pd/C) and H2 to afford the corresponding secondary amine in excellent yields. Simple work-up procedures allow for the isolation of pure compounds while avoiding purification via column chromatography. [ABSTRACT FROM AUTHOR]

Application of a trickle bed reactor (TBR) renders a very compact solution to carry out direct synthesis of hydrogen peroxide in water over a carbon supported palladium. The laboratory scale reactor was filled with silica particles (50–70 mesh) physically mixed with 37.5 to 75 mg of 5%Pd/C particles. The reaction conditions applied were 15 °C, 15–28 barg, 0.5 to 6 mL min −1 of liquid and 4.0–4.5 mL min −1 of gas flowrate (86.7/11/2.23 mol% of CO 2 /O 2 /H 2 ). Thus, we demonstrated that the ratio between H 2 and Pd is one of the key factors to achieve optimized, higher yields of hydrogen peroxide. Consequently, low H 2 concentrations lead to low productivities. One of the least studied parameters, addressed here, is the ratio between the bed filling (SiO 2 ) and the catalyst; i.e. the active catalytic species dilution effect. In short, it was found that when the amount of Pd was reduced below 0.094 mg Pd cm −3 SiO 2 the highest productivity of H 2 O 2 could be achieved. The selectivity obtained were between 5.3 and 38.0%, respectively, corresponding to turn-over-frequencies (TOF) ranging from 65 to 921 mmol H 2 O 2 gPd −1 h −1 . [ABSTRACT FROM AUTHOR]

The continuous flow Suzuki-Miyaura reaction between various haloarenes and arylboronic acids was successfully achieved within only ca. 20 s during the single-pass through a cartridge filled with palladium on carbon (Pd/C). No palladium leaching was observed in the collected reaction solution by atomic absorption spectrometry (detection limit: 1 ppm). [ABSTRACT FROM AUTHOR]

A large variety of halogenated nitroarenes have been selectively reduced with hydrazine hydrate in the presence of Pd/C to give the corresponding (halogenated) anilines in good yield. [ABSTRACT FROM AUTHOR]

An N-heterocyclic carbene and phosphite synergistically enhanced Pd/C catalyst system has been developed for of aryl chlorides and aryl boronic acids from commercially available Pd/C with sterically demanding N, N′-bis(2,6-diisopropylphenyl)imidazolylidene and trimethylphosphite. A remarkable increase in of Pd/C was observed when used along with 1 equiv. N, N′-bis(2,6-diisopropylphenyl)imidazolium chloride and 2 equiv. phosphite with respect to palladium in appropriate solvents that were found to play a crucial role in Pd/C-NHC-P(OR)3-catalyzed . A dramatic ortho-substitution effect of carbonyl and nitrile groups in aryl chlorides was observed and explained by a modified quasi-heterogeneous mechanism. The Pd/C catalyst could be easily recovered from reaction mixtures by simple filtration and only low palladium contamination was detected in the biparyl products. A practical process for the synthesis of 4-biphenylcarbonitrile has therefore been developed using the N-heterocyclic carbene/phosphite-assisted Pd/C-catalyzed . Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: A facile, mild, efficient, and copper-free method has been developed for the synthesis of 2-substituted indoles via domino Sonogashira coupling/cyclization reaction catalyzed by ZnCl2 and palladium on carbon with simultaneous formations of C–C and C–N bonds. [Copyright &y& Elsevier]

Catalytic hydrogenation of 2-cyano-2-(2-nitrophenyl)acetates bearing an electron withdrawing substituent to the nitrile, using Hantzsch ester catalyzed by Pd/C, affords 2-aminoindoles in good to excellent yields. [ABSTRACT FROM AUTHOR]

Abstract: Enantioselective hydrogenation of α-phenylcinnamic acid was investigated on Pd/C catalysts prepared in our laboratory to compare activity and selectivity with those on commercial Pd/C and Pd/TiO2 catalysts. The Pd/C catalysts after the 353 K-H2-pretreatment exhibited satisfactory and comparable performances obtained with commercially available best ever Pd/C by optimizing catalyst preparation. In contrast to Pd/TiO2, a high loading of Pd is not necessary with Pd/C, but only 5% loading on a certain activated carbon was found to result in high e.e. It is suggested that the optimum size or size-distribution of Pd metal particle are different between the two supports, suggesting a support effect of this catalyst system. [Copyright &y& Elsevier]

Abstract: The simultaneous use of catalytic amount of palladium on carbon (Pd/C) and Mg metal (1.5–2.0 equiv vs. Cl numbers of the substrates) in MeOH achieved the complete dechlorination of a variety of aryl chlorides at room temperature under a nitrogen atmosphere in the absence of hydrogen gas. The present method could be successfully used for the detoxification of PCBs based on the dechlorinaton reaction. Both virgin PCBs, such as Aroclors 1242, 1248 and 1254, and used PCBs as a high-tension capacitor oil, were smoothly dechlorinated into harmless biphenyl without any byproducts within 2h at rt. The distinctive features of this method are convenience and safety due to no needs for the pretreatment of catalyst and Mg and complete degradation of PCBs under mild conditions without hydrogen gas. [Copyright &y& Elsevier]

Abstract: The solvent-free and solid-phase hydrogenation of various reducible functionalities was efficiently catalyzed by heterogeneous palladium on carbon (Pd/C) under ambient hydrogen pressure and temperature. The Pd/C-catalyzed Suzuki–Miyaura coupling reaction between solid aryl bromides and solid arylboronic acids to generate the corresponding solid biaryls was also achieved under the totally solid-phase conditions. [Copyright &y& Elsevier]

Abstract: We report herein on the catalytic hydrotreatment of crude bio-oil, produced from the hydrothermal liquefaction of a microalga (Nannochloropsis sp.) over palladium on carbon (5% Pd/C) in supercritical water (SCW) at 400°C and 3.4MPa high-pressure H2. Influences of wide ranges of reaction time (varied from 1 to 8h) and catalyst loading (varied from 5 to 80wt%) on treated oil composition and yield, gas products composition and yield, and hydrogen consumption were explored. The C, H and energy recoveries were determined. The results demonstrated that longer reaction times and higher catalyst loadings did not favor the treated oil yield due to the increasing amount of gas and coke products formation but did lead to treated bio-oil with higher higher-heating-value (HHV) (41–44MJ/kg) than that of the crude feed. Highest HHV of treated oil (∼44MJ/kg) was obtained after 4h using an 80wt% intake of catalyst on crude bio-oil. The product oil produced at longer reaction times and higher catalyst loadings, which was a freely flowing liquid as opposed to being the viscous, sticky, tar-like crude bio-oil material, was higher in H and lower in O and N than the crude feed, and it was essentially free of sulfur (below detection limits). Typical H/C and O/C molar ratios ranges for the bio-oils treated at different reaction times and catalyst loadings were 1.65–1.79 and 0.028–0.067, respectively. The main gas-phase products were unreacted H2, CH4, CO2, C2H6, C3H8 and C4H10. Overall, many of the properties of the treated oil obtained from catalytic hydrotreatment in SCW in the presence of Pd/C are very similar to those of hydrocarbon fuels derived from fossil fuel resources. [Copyright &y& Elsevier]

The reaction of allyl bromide with phenylacetylene catalyzed by Pd/Al2O3 pellets and Pd/C powder was investigated. Bromoallylation of phenylacetylene took place to give a regioisomeric mixture of 1-bromo-substituted 1,4-dienes. The bromoallylation of phenylacetylene was successfully applied to a continuous flow synthesis using a stainless steel made column packed with Pd/Al2O3 pellets. [ABSTRACT FROM AUTHOR]

Abstract: Pd/C-catalyzed hydrogenation reactions are found to be highly temperature-dependent. The hydrogenation smoothly proceeds in the temperature range from ambient to the boiling point of the solvents, although the hydrogenation is suppressed at an elevated bath temperature of approximately 30°C above the boiling point of the solvent under ambient hydrogen pressure. [Copyright &y& Elsevier]

Relationship between substrate structure and enantioselectivity is studied for the asymmetric hydrogenation of 42 different (E)--disubstituted acrylic acids (propenoic acids) over cinchonidine-modified Pd/C. The β-phenyl group is indispensable for high enantioselectivity of α-phenylcinnamic acid (2,3-diphenylpropenoic acid, 81% ee), and substitution on this group affects markedly the selectivity. The high ee up to 92% was achieved by the -alkoxyphenyl substitution, and the selectivity is ascribed mainly to stronger interaction of the substrate with the chiral modifier on the catalyst surface. In contrast, substitution on the α-phenyl group does not affect notably the enantioselectivity (80–82% ee) or even the α-phenyl group itself is not indispensable but replaceable with a properly bulky group for the high enantioselectivity. [Copyright &y& Elsevier]

Pd/C-catalyzed transfer hydrogenation with Hantzsch ester1,4-dihydropyridine was found to be very effective for the selective reduction of N-(alkoxy(aryl)methyl) benzamide compounds to the corresponding benzamides. The reaction conditions, solvent effects, and reaction mechanism were discussed in the present work. [ABSTRACT FROM AUTHOR]

Abstract: A method for the rapid, safe hydrogenation of alkenes and deprotection of benzyl ethers and carboxybenzyl amides is described using catalytic transfer hydrogenation under microwave heating conditions. Commonly available Pd/C catalyst is extremely effective with 1,4-cyclohexadiene as the hydrogen transfer source. In general, the reactions are complete within five minutes at 100°C. [Copyright &y& Elsevier]

Abstract: The kinetics of o-chlorotoluene hydrogenolysis in the presence of 3%, 5% and 10% Pd/C catalysts was experimentally investigated in an alkaline –n-heptane – gaseous hydrogen system. The main product of hydrogenolysis was toluene. Kinetic characteristics for the reaction were obtained at temperatures of 20, 40 and 60°C at atmospheric pressure of hydrogen for all catalysts; the effectiveness of the latter in o-chlorotoluene hydrogenolysis was compared. The pseudo-zero-order rate constants and times of 90% conversion for each of the catalysts at 40 and 60°C were quite similar. The overall kinetic constants were obtained assuming the Langmuir–Hinshelwood mechanism. The activation energies of o-chlorotoluene hydrogenolysis for these catalysts were calculated. The selectivity of the reacting system was evaluated in competitive experiments with o-chlorotoluene, 1,2-dichlorobenzene and 4-chlorobiphenyl. The stability of the catalysts in a hydrogenolytic environment was tested. [Copyright &y& Elsevier]

Abstract: Palladium on carbon is used as a precatalyst for Suzuki–Miyaura reaction of aryl chlorides and aryl boronic acids. An efficient catalyst system is obtained that allows the reaction of substrates that are difficult to couple under ligand free conditions. This includes electron rich and sterically hindered aryl chlorides as well as electron deficient and sterically hindered boronic acids. We have discovered that the amount of ligand needed to catalyze these reactions can be significantly decreased by incorporating an incubation period. This study also provides valuable insight into the mechanism of the Pd/C-catalyzed Suzuki–Miyaura cross-coupling. For example, mercury poisoning studies provide evidence that the active catalytic species is homogeneous. However, catalyst reuse and low metal contamination indicate that this system retains many of the advantages of a heterogeneous catalyst. From these results, a catalytic cycle is proposed. [Copyright &y& Elsevier]

Enantioselective hydrogenation of ( E)- α-alkyl- β-arylpropenoic acids was studied over the cinchonidine-modified Pd/C under the conditions optimized for ( E)- α, β-diarylpropenoic acids. Enantiomeric excess (ee) of the product was increased by adjusting the α-alkyl group as a properly bulky isopropyl. The ee was as high as 80% when the β-group is phenyl, and reached 86% with p-anisyl group. Stereoselection of those substrates is similar to that of ( E)- α, β-diarylpropenoic acids. [ABSTRACT FROM AUTHOR]

Recently we have reported undesirable and frequent deprotection of the TBDMS protective group of a variety of hydroxyl functions occurred under neutral and mild hydrogenation conditions using 10% Pd/C in MeOH. The deprotection of silyl ethers is susceptible to significant solvent effect. TBDMS and TES protecting groups were selectively cleaved in the presence of acid-sensitive functional groups such as TIPS ether, TBDPS ether and dimethyl acetal under hydrogenation condition using 10% Pd/C in MeOH. In contrast, chemoselective hydrogenation of reducible functional groups such as acetylene, olefin and benzyl ether, proceeds in the presence of TBDMS or TES ethers in AcOEt or MeCN. [Copyright &y& Elsevier]

Commercial Pd/C catalysts show different catalytic activity toward the deprotection of silyl and THP ethers. The Pd/C purchased from Merck and ACROS exhibits marked tendency to cleave these protective groups unexpectedly without hydrogen conditions although Aldrich''s Pd/C (20,569-9) is inactive in the absence of hydrogen. It was proved that the Pd/C disparity toward the deprotection of TES and THP ethers results from residual acids and/or palladium chloride in the production process of Pd/Cs. Although a TES ether cleavage reaction in the absence of hydrogen and a THP ether cleavage reaction in the presence of hydrogen using 10% Pd/C were recently published, we could conclude they were only an acid-catalyzed solvolysis, the acid being released from the catalyst. Hydrogen is essential for the actual 10% Pd/C-catalyzed cleavage of TES ethers and THP ethers which must be stable under the true Pd/C-catalyzed hydrogenation conditions. [Copyright &y& Elsevier]

The benzyl group is a protecting group for benzimidazoles and imidazoles that can survive acidic, basic, oxidizing, and reducing conditions. Deprotection, however, can require vigorous and potentially non-chemoselective methods. The triethylsilane–Pd/C reduction system is an exceptionally mild, convenient, and efficient method for deprotecting N -benzylbenzimidazoles that are unsubstituted at the 2- and 4-positions as well as suitably substituted N -benzylimidazoles. [ABSTRACT FROM AUTHOR]

The Pd/C-catalyzed reactions, including reduction reactions and cross-coupling reactions, play an irreplaceable role in modern organic synthesis. Compared to the homogeneous palladium catalyst system, the heterogeneous Pd/C catalyst system offers an alternative protocol that has particular advantages and applications. Herein, a review on Pd/C-catalyzed reactions is presented. Both the advances in Pd/C-catalyzed methodologies and the application of Pd/C-catalysis in total synthesis are covered in this review. [ABSTRACT FROM AUTHOR]

A new polysaccharide multilayer biodegradable film was developed and tested, which can scavenge ethylene and inhibit ethylene action by releasing 1-methylcyclopropene (1-MCP). The film was fabricated with the stacking order of hydrophobic ethyl cellulose outer layer, a mixture of 1-methylcyclopropene and palladium on carbon (1-MCP-Pd/C) middle layer and hydrophilic hydrogel inner layer. The excess water produced by fruits and vegetables was absorbed by inner layer, avoiding the accumulation of condensed water. Meanwhile, the increase of the permeability of the inner hydrogel layer caused by moisture absorption facilitated manipulation of antistaling agent. SEM, TG and DSC proved that the functional components were successfully loaded on the film. Gas chromatography analysis results demonstrated that the 1-MCP release rate and ethylene removal rate could be controlled by adjusting the humidity (50% RH to 100% RH). The effects of the film on the main quality attributes of Agaricus bisporus were evaluated at 20 °C. This prepared functional film could delay the softening, browning and weight loss of mushrooms, maintain the integrity of mushroom cell membrane, maintain ascorbic acid content and soluble solid content, and inhibit the activity of ethylene synthesis-related enzymes. • Film with function of ethylene manipulation was prepared. • Hydrogel layer was used for humidity-controlled release and absorption of 1-MCP and ethylene. • HEM film reduce the damage of ethylene to Agaricus bisporus. • The humidity responsive system provided a new pathway for active packaging. [ABSTRACT FROM AUTHOR]

Abstract: Hantzsch 1,4-dihydropyridine (HEH), a well-known model compound of coenzyme NAD(P)H was found as an efficient reducing agent in hydrogenation of unactivated olefins catalyzed by Pd/C. α,β-Unsaturated ketones also underwent hydrogenation, affording the corresponding saturated ketones selectively. [Copyright &y& Elsevier]

A method has been developed for the synthesis of 2,2′- and 3,3′-biquinolines and of 4,4′-bipyridine based on the coupling of 2- and 3-bromoquinoline or 4-bromopyridine using a Pd/C-hydrazine-KOH catalytic system. [ABSTRACT FROM AUTHOR]

A large variety of halogenated nitroarenes have been selectively reduced with hydrazine hydrate in the presence of Pd/C to give the corresponding (halogenated) anilines in good yield.

We previously reported octahydropyrrolo[1,2-a]pyrazine derivative 2 (T-3256336) as a potent antagonist for inhibitors of apoptosis (IAP) proteins. Because compound 2 was susceptible to MDR1 mediated efflux, we developed another scaffold, hexahydropyrazino[1,2-a]indole, using structure-based drug design. The fused benzene ring of this scaffold was aimed at increasing the lipophilicity and decreasing the basicity of the scaffold to improve the membrane permeability across MDR1 expressing cells. We established a chiral pool synthetic route to yield the desired tricyclic chiral isomers. Chemical modification of the core scaffold led to a representative compound 50, which showed strong inhibition of IAP binding (X chromosome-linked IAP [XIAP]: IC50 23 nM and cellular IAP [cIAP]: IC50 1.1 nM) and cell growth inhibition (MDA-MB-231 cells: GI50 2.8 nM) with high permeability and low potential of MDR1 substrate., (Copyright © 2013 Elsevier Ltd. All rights reserved.)