Cyclohexylamine Research Articles

Pyranine Interaction with Amines in Micelles.

The fluorescence behavior of pyranine in anionic micellar system of sodium dodecyl sulphate was studied in the presence of selected amines. The amines included cyclopropylamine (CPA), ethylenediamine (EDA), benzylamine (BA), dibutylamine (DBA), cyclohexylamine (CHA), and polyethylenediamine (PEDA). All the studied amines quenched the intensity of pyranine. Study was performed in 0.05M and 0.1M SDS. The thermodynamic parameters were determined in order to understand the quenching of pyranine by the studied amines. Change in Gibbs free energy and quenching was found higher in 0.05M SDS concentration and was found lower when SDS concentration was increased to 0.1M SDS. Pyranine quenching by the amines studied were treated with an extended Stern-Volmer equation that produced the Stern-Volmer constant ([Formula: see text]). Binding constant (Kb), number of binding stoichiometry (n) and Gibbs free energy change (ΔGbinding) were found higher for lower surfactant concentration as compare to higher surfactant concentration. More negative (-ve) the Gibbs free energies more will be the quenching, higher will be the sensitivity and vice versa. The Gibbs free energies for all the studied amines were found in the order as cyclopropylamine > ethylenediamine > benzylamine > dibutylamine > cyclohexylamine > polyethylenediamine. Fluorescence quenching of pyranine by amines in aqueous SDS is reproducible and is useful for the determination of amines in environmental samples.

Start-Up of New Cyclohexylamine and Dicyclohexylamine Plants at BC MCHZ Ostrava and at The Wanhua Plant, Yantai, China

The development and realization of cyclo- and dicyclohexylamine technologies at MCHZ Ostrava from the 1970s to the present, in which the production plant is a part of the Wanhua-BorsodChem Group, is described. In the course of more than fifty years of development, the production of cyclohexylamine (CHA) has increased by two orders of magnitude. With the introduction of the scrubbing of NH3 from the circulation gases, hydrogen has been saved. The quality of both amines has increased, their yield being more than 99.0%. The production of CHA by hydrogenation of aniline is accelerated by a special, very active and selective cobalt catalyst with a long service life of approximately 20 years.

Organocatalyzed Synthesis, DNA Binding and Microbial Studies of Warfarin Analogues

A noval chiral sec-amine/amidine-base hybrid catalyst, N [S-carbonylprolyl] cyclohexyl Amine is described, which is able to catalyze conjugate addition of 6-Methyl-4-hydroxypyran and 2-Hydroxy-naphthaquinone with various benzylideneacetones through Michael reactions that directly gives anticoagulant Warfarin analogues. These analogues were prepared in good yields (54–82%) and in good enantiomeric excess (50–75%). Identification of synthesized compounds was done by physio-chemical properties and spectral analysis (1H-NMR andamp; 13C-NMR).These compounds were further investigated for their antimicrobial (antibacterial andamp; antifungal) activities and DNA-binding studies. Antimicrobial studies were carried out by Disc Diffusion while DNA-binding studies were carried out by Cyclic Voltammetry and UV-Visible spectroscopy. These studies showed that the compounds showed significant interaction with DNA. Some analogues also imparted prominent antimicrobial activities.

Design, synthesis, pharmacological evaluation, and in silico studies of the activity of novel spiro pyrrolo[3,4-d]pyrimidine derivatives.

In the present study, spiro compounds are shown to have distinctive characteristics because of their interesting conformations and their structural impacts on biological systems. A new family of functionalized spiro pyrrolo[3,4-d]pyrimidines is prepared via the one-pot condensation reaction of amino cyclohexane derivatives with benzaldehyde to prepare fused azaspiroundecanedione and azaspirodecenone/thione derivatives. A series of synthesized spiro compounds were scanned against DPPH and evaluated for their ability to inhibit COX-1 and COX-2. All compounds exhibit significant antiinflammatory activity, and they inhibited both COX-1 and COX-2 enzymes with a selectivity index higher than celecoxib as a reference drug. The most powerful and selective COX-2 inhibitor compounds were 11 and 6, with selectivity indices of 175 and 129.21 in comparison to 31.52 of the standard celecoxib. However, candidate 14 showed a very promising antiinflammatory activity with an IC50 of 6.00, while celecoxib had an IC50 of 14.50. Our findings are promising in the area of medicinal chemistry for further optimization of the newly designed and synthesized compounds regarding the discussed structure-activity relationship study (SAR), in order to obtain a superior antioxidant lead compound in the near future. All chemical structures of the novel synthesized candidates were unequivocally elucidated and confirmed utilizing spectroscopic and elemental investigations.

Photoredox-Enabled Dearomatization of Protected Anilines: Access to Cyclohexadienone Imines with Contiguous Quaternary Centers

A photoredox-enabled alkylative dearomatization of protected anilines is reported. Under Ir catalysis and light irradiation, an N-carbamoyl-protected aniline and an α-bromocarbonyl compound could be simultaneously activated, and the two resulting radical species then recombine with each other to afford a dearomatized cyclohexadienone imine as the major product. A series of such imines with contiguous quaternary carbon centers were prepared, which can be further converted into cyclohexadienones, cyclohexadienols, and cyclohexyl amines.

Decarboxylation-Induced Defects in MOF-Derived Ni@C Catalysts for Efficient Chemoselective Hydrogenation of Nitrocyclohexane to Cyclohexanone Oxime

In this work, MOF-derived Ni@C catalysts with rich defects were synthesized using a facile thermally decarboxylation-induced defect strategy for nitrocyclohexane (NCH) hydrogenation. It was found that the strong metal–support interaction (SMSI) between the defect-rich carbon and Ni promotes the dispersion of Ni nanoparticles, reduces the Ni particle size, and affects the surface charge state of Ni to form electron-deficient Ni, thus exhibiting outstanding catalytic activity. Additionally, in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) illustrates that the transformation path of nitrosocyclohexane (N-NCH) is critical for obtaining high selectivity to cyclohexanone oxime (CHO). Furthermore, the density functional theory (DFT) calculations confirm that the SMSI between the defect-rich carbon and Ni leads to the formation of electron-deficient Ni with a lower d-band center, which can weaken the adsorption of N-NCH and CHO, enhance the adsorption of N-cyclohexylhydroxylamine (N-CHH) and cyclohexylamine (CHA), reduce the reaction energy of the N-NCH to CHO, and increase the reaction energy of the N-NCH to CHA, thus showing the highest selectivity to CHO. Under optimum conditions, Ni@DC-0.06 gives 97.2% selectivity to CHO at 95.2% NCH conversion.

A computational investigation on the cyclohexylamine recognition using the pure and Cu-doped BN nanotube

ABSTRACT We scrutinise the adsorption of cyclohexylamine (CHA) on pure and Cu-doped BN-nanotube (Cu@BN-NT) through density functional theory calculations. CHA had a weak interaction with the pristine BN-NT, making BN-NT not suitable to be used as a sensor. However, there was a substantial rise in the reactivity and sensitivity of the BN-NT after replacing the B with metal Cu, based on the standard Gibbs free energy of formation. There is a reduction in the energy gap of the HOMO–LUMO of Cu@BN-NT from 2.28 to 1.42 eV (∼ −37.7%) when CHA was adsorbed, which substantially increased the electrical conductivity. Hence, converting the substantial change in the electrical conductivity into an electronic signal was possible, which demonstrated that the Cu@BN-NT was an encouraging sensor to detect CHA. The computed recovery time for the Cu@BN-NT was 26.8 s, which is short.

Sequential hydrogenation of nitroaromatics to alicyclic amines via highly-dispersed Ru-Pd nanoparticles anchored on air-exfoliated C3N4 nanosheets.

Developing efficient and green catalytic systems is highly desired in the syntheses of alicyclic amines via hydrogenation of nitroaromatics. Herein, we developed Ru-Pd dual active site catalysts in which Ru and Pd species were anchored and highly dispersed on air-exfoliated carbon nitride (Ru-Pd/C3N4-air). As-prepared catalysts were employed in the hydrogenation of nitrobenzene (NB) to cyclohexylamine (CHA). Compared with single Ru or Pd based catalysts, Ru-Pd dual active site catalysts obtained a higher CHA production rate of 26.7 mol CHA mol-1 Ru·Pd h-1 at 80 °C and 3 MPa H2. The activation energy for the hydrogenation of the nitro group and benzene ring was calculated as 26.26 kJ mol-1 and 66.30 kJ mol-1, respectively. Intrinsic kinetic studies demonstrated that Pd was the dominant metal for hydrogenation of nitro group, while Ru was dominant for benzene ring. Thereinto, the corresponding non-dominant metals enhanced activation and dissociation of H2, thereby improving catalytic activity significantly. This excellent performance of Ru-Pd catalysts could be attributed to highly dispersed Ru-N x and Pd-N x at a nanoscale distance, which was conducive to metal-assisted hydrogenation. Stability investigation showed that the performance of Ru-Pd catalysts could be essentially maintained at a high level. Additionally, the substrate scope could be successfully extended to hydrogenation of other nitroaromatics with different substituents.

The effect of spermidine and methionine application thorough two biosynthetic paths on flowering of early and late flowering genotypes of eggplant (Solanum melongena L.)

This research was carried out to investigate the effect of Spermidine (SPD) and its synthesis routes on flowering and fruit formation in two early and late flowering genotypes of eggplant in a completely randomized design. For this reason, the spermidine route was blocked with Cyclohexylamine (CHA) and Methylglyoxal-bis-guanilhydrazone (MGBG) separately to investigate each route effect. On the other hand, the route synthesis promotes with the precursor methionine (200 mg/L) and spermidine (0.5 and 1 mM), and distilled water was used as a control treatment. These treatments were applied in vegetative growth and ten days after flowering. Results showed that SPD increased the traits such as length of style, long-styled flowers, fruit number, and yield. The lowest amount of day to flowering was observed in SPD, 0.5 mM at early flowering genotypes. The highest fruit weight and yield were in SPD, 1 mM at late flowering genotype. SPD improved flowering and fruit characteristics in both genotypes. Conclusively, methionine precursor path's blocking had more inhibitory effects on reproductive and fruiting characteristics in the late flowering genotype, i.e., methionine was a more critical precursor in spermidine production induced flowering than spermidine application. The activity of synthetic pathways and their effects on different processes depends on the different cultivars and stages of the developmental stage of the eggplant.

Experimental and DFT investigation on the role of aromaticity on the stability of hydrogen bonded complexes of cyclohexanone with amines and hydroxyl compounds

The existence of intermolecular hydrogen bonded interaction between four structurally hydroxyl and amino compounds namely, phenol (PHE), aniline (ANI), cyclohexanol (CHL) and cyclohexylamine (CHA) with cyclohexanone (CHE) was investigated in n-hexane medium at 303 K by experimental methods (ultrasonic, UV–Visible, IR spectral analysis) and theoretical (DFT, NCI) methods. From the acoustical and excess thermo-acoustical parameters, strong solute–solute interactions of hydrogen bonded type between the solutes were established. The formation of 1:1complexes between cyclohexanone and hydroxyl, amino compounds was confirmed by UV–visible spectral method and the presence of hydrogen bonding in these complexes was proved by IR spectrum. The stability constant of the four hydrogen bonded complexes was calculated by both ultrasonic and UV–Visible spectroscopic methods. Interestingly, it was found that the order of strength of hydrogen bonding between CHE and hydroxyl as well as amino compounds is in the order CHE-PHE > CHE-ANI > CHE-CHL > CHE-CHA. DFT calculations, NBO analysis and NCI plots were also made to quantify the nature of stabilizing interactions between CHE and hydroxyl and amino compounds. Our computed results are in good agreement with the experimental observations. It is observed that aromatic moiety adjacent to hydrogen donor influences significantly the stability of the H-bonded complexes.

Water accelerated activity of Ru NPs in sequential hydrogenation of nitrobenzene to cyclohexylamine

It is difficult to balance the two separate and connected reaction steps in the sequential hydrogenation of nitrobenzene (NB) to cyclohexylamine (CHA) via only tuning the active sites. In this work, we optimize the activity of supported Ru NPs in the one-pot NB hydrogenation to CHA by tuning the surface hydrophobicity of the catalysts and by investigating the solvation effect. The Ru supported on hydrophobic mesoporous silicas is more active than that on hydrophilic mesoporous silicas, which may be attributed to the enrichment effect of the former one for hydrophobic NB. Furthermore, the activity of Ru is significantly promoted with the addition of H2O in the reaction system. Systematic studies suggest that the water promotion effect is mainly related with the decreased adsorption strength of NB on Ru surface and the water accelerated H* transfer during the NB hydrogenation process. Our primary results suggest that the modification of the surface properties of the catalysts and the deeper understanding of the solvation effect play an important role in one-pot cascade reactions.

Surface Coordination Decouples Hydrogenation Catalysis on Supported Metal Catalysts

Surface Coordination Decouples Hydrogenation Catalysis on Supported Metal Catalysts

Engineering pore structure and acidity of ferrierite zeolites by organic structure directing agents for n-butene isomerization

Zeolites are important heterogeneous catalysts in industrial applications, but always suffer from deactivation caused by carbon deposition. In this work, a simple strategy was developed to engineer Ferrierite (FER) zeolites with different pore structure and distribution of Brønsted acid sites by using different organic amine structure directing agents, i.e., pyrrolidine (PY), ethylenediamine (EDA), cyclohexylamine (CyHA). The obtained PY-FER not only exhibited optimal hierarchical porosity, but also showed the highest density of Brønsted acid sites inside micropores and lowest Lewis/Brønsted acid ratio (L/B). Based on the corresponding performance in n-butene skeletal isomerization, it can be concluded that high L/B is prone to coke formation, while a balance between micropores and mesopores is beneficial to the reduction of carbon deposition. Besides, a model y=y0−Aexp(−Kt) was established to describe the behavior of the carbon deposition, which matches well with the properties of the zeolites. These findings are significant for the design of zeolites.

Synthesis and Characterisation of Dicyclohexyl Urea by the improved Green Methodology

The reaction of cyclohexyl amine with urea under solvent-free condition, one-step and one-pot synthesis via transamination for industrial production is studied where, cyclohexyl amine is heated with urea to give desired product DCU in molar yield.

Enhanced photocatalysis and photodetection using highly crystalline CZTS thin films optimized using stabilizers

In this work, high crystalline copper zinc tin sulfide (CZTS) thin films optimized using various stabilizers were fabricated using a low-cost non-vacuum-based spin coating method. The structural and optical properties of these films were characterized by XRD, FESEM, Raman spectroscopy, XRF and PL. Kesterite CZTS structure and its composition were confirmed by XRD and XRF, respectively. Trace secondary phase peaks were found using Raman spectroscopy and an optical band gap of 1.53 eV was obtained using photoluminescence measurements. In addition, density functional theory calculations were performed to understand the role of stabilizers in the formation of thin films. The results indicated variation in the crystallinity of the films upon changing the stabilizers. Photocatalytic degradation performance and photocurrent response were estimated to assess the crystallinity-property relationship. The thin film obtained using cyclohexylamine (CHA) stabilizer showed the highest methylene blue (MB) degradation i.e. 97% in 180 min with a reaction rate constant of 0.019 min−1 which is 73% greater than the thin films without stabilizers. The photocurrent response of this film was found to be 29 μA/cm2, which was twice that of CZTS thin films without stabilizers. It was found the use of a cyclohexylamine stabilizer in CZTS thin film preparation improved the structural and optical characteristics of thin films. This study is significant in the context of obtaining high-quality CZTS thin films for efficient solar photovoltaic, photocatalysis and other optoelectronic devices.

Treatment of Organic Wastewater by Supercritical Water Oxidation

Supercritical water oxidation (SCWO) is a robust process in removing the hazardous organic wastes. Therefore, it is necessary to improve the SCWO process to eliminate the organic hazardous wastes. In present work, SCWO process used cyclohexylamine (CHA) as the organic chemical model. The co-oxidizers consisted of propylene glycol (PG), methanol and the oxygen source was hydrogen peroxide. The experiments were conducted using at a laboratory scale. A plug-flow reactor was utilized at different operating temperatures ranging from 425 to 525 ºC, the critical pressure was 25 MPa. At working temperatures, the co-oxidizer and the oxidant ratios were also investigated . The results indicated that the temperature had an impact on the removal efficiency of cyclohexylamine. The maximum total organic carbon removal (TOC) in the presence of propylene glycol was achieved with 98% at 525 ºC and the residence time was 14 s.

Multi-functional oilfield production chemicals: maleic-based polymers for gas hydrate and corrosion inhibition

Several chemical problems can occur during the production of oil and gas through flow lines. This includes corrosion, scale deposition and gas hydrate plugging. Three separate chemicals may be needed to treat these issues. Kinetic hydrate inhibitors (KHIs) are used in cold oil or natural gas production flow lines to prevent the formation and plugging of the line with gas hydrates. They are often injected concomitantly with other production chemicals such as corrosion and scale inhibitors. KHIs are specific low molecular weight water-soluble polymers with amphiphilic groups formulated with synergists and solvents. However, many corrosion inhibitors (CIs) are antagonistic to the KHI polymer, severely reducing the KHI performance. It would be preferable and economic if the KHI also could act as a CI. We have explored the use of maleic-based copolymers as KHIs as well as their use as film-forming CIs. KHIs were tested using a natural gas mixture in high pressure rocking cells using the slow constant cooling test method. A terpolymer from reaction of vinyl acetate:maleic anhydride copolymer with cyclohexy lamine and 3,3-di-n-butylaminopropylamine (VA:MA-60% cHex-40% DBAPA), gave excellent performance as a KHI, better than the commercially available poly(N-vinyl caprolactam) (PVCap). CO2 corrosion inhibition was measured by Linear Polarization Resistance (LPR) in a 1 litre CO2 bubble test equipment using C1018 steel coupons. The new terpolymer gave good CO2 corrosion inhibition in 3.6 wt% brine, significantly better than PVCap, but not as good as a commercial imidazoline-based surfactant corrosion inhibitor. The terpolymer also showed good corrosion inhibition efficiency at high salinity conditions, (density 1.12 g/cm3). VA:MA-60% cHex-40% DBAPA shifted the open-circuit potential to more positive values and significantly decreased the corrosion rate.

A new mechanism for pore enlargement in mesoporous materials and its application on biodiesel production

ABSTRACT In the conventional method of synthesis by using cyclohexylamine (CA) as template produces in the pore range of 0–3 nm. To enlarge the pore size which is suitable for biodiesel synthesis, the modified synthesis method is adopted by using CA as a template. In this novel method, pore size is enlarged to 7 nm. Cyclohexylamine was applied as a template for AlPO4 and AlSiO4 molecular sieves synthesis. In AlSiO4 synthesis, tetraethyl orthosilicate hydrolyzed to produce ethyl carbocation which is used for ethylation of CA in the presence of aluminum chloride. This ethylated CA size is large enough to produce a large pore size (7 nm). In AlPO4 two types of pore are produced with a pore size of 3 and 7 nm. The 3 nm are created by CA and 7 nm by the binding of CA with phosphoric acid. The synthesized materials are analyzed by physicochemical characterization. AlPO4 has a neutral framework, but the synthesized AlPO4 has acidity which is evidence for the CA binding with phosphoric acid. The synthesis of a promising catalyst (AlPO4-7 and AlSiO4-7) with an enlarged pore that can be effectively applied for the production of biodiesel from waste cooking oil (WCO) at room temperature. The acidity of the synthesized AlPO4 and AlSiO4 are 0.168 and 0.548 mmol/g. These catalysts are active at room temperature due to higher acidity. So the reaction takes place faster and it will reduce the reaction time. It is observed that AlSiO4 produces 90% biodiesel and AlPO4 produces 72% biodiesel with a shorter reaction time. This result reveals that 7 nm pores are suitable for biodiesel production. The diethyl ether selectivity of AlPO4 and AlSiO4 is 24% and 4%, respectively. This is due to the 3 nm pore size created by CA in AlPO4 and it favors diethyl ether synthesis.

The Role of Organic and Inorganic Structure-Directing Agents in Selective Al Substitution of Zeolite

Organic and inorganic structure-directing agents (SDAs) impact Al distributions in zeolite, but the insights into how SDAs manipulate Al distribution have not been elucidated yet. Herein, the roles of different SDAs such as cyclohexylamine (CHA), hexamethylenimine (HMI), and Na+ in selective Al substitution of MCM-49 zeolite are investigated comprehensively by multinuclear solid-state NMR. The results demonstrate that MCM-49 synthesized with HMI shows relatively more T6 and T7 Al, while more T2 Al is observed using CHA. The formation of T2 Al in both MCM-49(HMI) and MCM-49(CHA) is derived from Na+, while protonated HMIs show bias in incorporation of T6 and T7 Al. Most HMIs are occluded in protonated status, and about half of CHAs are occluded in nonprotonated status. The close spatial proximity between nonprotonated CHAs and Na+ synergistically promotes the formation of zeolite structure, leading to more Na+ ions occluded in the zeolite channel with preferential T2 Al substitution.

Computational and experimental study of molecular interaction in a ternary liquid mixture of cyclohexylamine+ethanol+benzene

In the present investigation, we undertake the study of molecular interaction in a ternary mixture of cyclohexylamine (CHA), ethanol (Eth) and benzene (B) theoretically as well as experimentally. We study the interaction between CHA dimer and complexes (Eth-CHA, B-CHA, CHA-Eth-B) theoretically using DFT (Density functional theory) with B3LYP/6-311++G(d,p) level theory in a gas phase. It includes the quantum chemical calculations of interaction energy, bond length, and identification of the intermolecular interaction from structural parameter analysis. Further, we experimentally determine the excess thermo-acoustic parameters of the mixture. For this, we have measured the ultrasonic velocity (u) and density (ρ) of the ternary mixture of cyclohexylamine+ethanol+benzene and of pure components at 303, 308 and 313 K temperature. From these experimental values of u and ρ, excess thermo-acoustic parameters have been estimated using standard relation. The variations in excess acoustic parameters with the concentration of cyclohexylamine (x 1 ) are discussed in terms of the interactions and molecular geometry of the liquid mixture. At lower concentration, weak interactions dominate while on increasing x 1 strong forces between molecules take place. The strong H-bonding interaction between CHA- ethanol molecules and molar volume differences of pure components leads to interstitial accommodation of molecules. Experimentally determined excess properties behaviour is supported by the theoretical calculation.