Benzylamine Research Articles

Thermodynamic Modeling of an Aqueous N,N-Dimethyldipropylenetriamine and Benzylamine Blend for Efficient CO2 Capture.

This study evaluates the carbon dioxide (CO2) capture capabilities of a novel aqueous blend of N,N-dimethyldipropylenetriamine (DMDPTA) and benzylamine (BA). The solvent properties such density, vapor- liquid equilibrium (VLE) of CO2 in the solvent, CO2 absorption enthalpy are evaluated experimentally for solvent composition of (5 mass% DMDPTA + 25 mass% BA), (10 mass% DMDPTA + 20 mass% BA), and (15 mass% DMDPTA + 15 mass% BA). Solvent density were measured in the temperature range of 303.15K-333.15K and correlated using Redlich-Kister excess molar volume model, with a low average absolute relative deviation (AARD) of 0.014. VLE data was measured using a custom-made stirred VLE cell, within CO2 partial pressure range of 2-200 kPa and at temperatures 313.15K, 323.15K and 333.15K. Equilibrium CO2 solubility data were correlated using a modified Kent-Eisenberg model, achieving an AARD of 1.5%. Enthalpy of CO2 absorption was measured at 313.15 K using a Meter Toledo reaction calorimeter. Results indicated that under similar process conditions and solvent composition, (DMDPTA+BA) blends exhibited significantly higher CO2 loading and low absorption enthalpy compared to aqueous BA and monoethanolamine (MEA) solvent alone indicating the potential of (DMDPTA+BA) blend as efficient CO2 capture solvent.

Rationally designed photothermal-pyroelectric Fe0.9Ni0.1S2/ZnSnO3 Z-scheme heterojunction for promoting electrical charge polarization towards optimized photocatalytic H2 evolution and intermolecular N-N coupling reaction

Developing a photocatalytic composite system that can couple hydrogen (H2) evolution and benzylamine (BA) oxidation is a challenging task, especially while avoiding sacrificial agents and value-added chemicals. Here, a practical approach is reported to develop a photothermal-pyroelectric-Fe0.9Ni0.1S2/ZnSnO3 photocatalytic system with core–shell and Z-scheme heterostructure via hydrothermal and annealing methods. Although Fe0.9Ni0.1S2 nanoparticles (NPs) could convert most of near-infrared (NIR) light energy into heat energy to drive the pyroelectric effect of ZnSnO3, it also results in temperature fluctuations (ΔT) in the system, causing natural polarization and thermoelectric effects under the condensed water circulation. As a result, the as-designed Fe0.9Ni0.1S2/ZnSnO3-2 composites could yield up to 7.194 mmol g-1h−1 with exceptional photocatalytic H2 evolution under simulated sunlight. This result is 5.41 and 4.92-fold those of Fe0.9Ni0.1S2 and ZnSnO3, respectively, with 16.66 % apparent quantum yield (AQY) under 365 nm monochromatic light. At the same time, the composites could also oxidize BA and yield up to 6.640 mmol g-1h-1n-benzylidene benzylamine (NBBA) with a 90.2 % selectivity. Due to the synergistic effect of Z-scheme’s built-in electric field and photothermal-pyroelectric of Fe0.9Ni0.1S2/ZnSnO3, the surface charges released on them could direct the charge transfer pathways and restrain their recombination with accelerated electron transfer kinetics, thus extending the carrier lifetime. This work offers a new perspective for designing electrical charge polarized by the photothermal-pyroelectric effect, which can enhance H2 evolution and BA oxidation concurrently.

Room-Temperature Single-Phase Synthesis of Semiconducting Metal-Covalent Organic Frameworks With Microenvironment-Tuned Photocatalytic Efficiency.

In order to improve the solubility of metallated monomers and product crystallinity, metal-covalent organic frameworks (MCOFs) are commonly prepared via high-temperature sol-vothermal synthesis. However, it hampers the direct extraction of crystallization evolution information. Exploring facile room-temperature strategies for both synthesizing MCOFs and exploiting the crystallinity mechanism is extremely desired. Herein, by a novel single-phase synthetic strategy, three MCOFs with different microstructure is rapidly prepared based on the Schiff base reaction between planarity-tunable C3v monomers and metallated monomers at room temperature. Based on detailed time-dependent experiments and theoretical calculations, it is found that there is a planarity-tuned and competitive growth relationship between disordered structures and crystal nucleus for the first time. The high planarity of monomers boosts the formation of crystal nucleus and rapid growth, suppressing the forming of amorphous structures. In addition, the microenvironment effect on selective photocatalytic coupling of benzylamine (BA) is investigated. The strong donor-acceptor (D-A) MCOF exhibits efficient photocatalytic activity with a high conversion rate of 99% and high selectivity of 99% in 5h under the 520nm light irradiation. This work opens a new pathway to scalable and efficient synthesis of highly crystalline MCOFs.

Investigation of intermolecular interactions in binary mixtures of N,N-dimethyl benzyl amine with higher alkanols (N,N-dimethyl benzyl amine with 1-octanol, 1-nonanol, 1-decanol)

ABSTRACT Measurements of densities (ρ), speeds of sound (u), and viscosities (η) for binary mixtures of N,N-dimethyl benzyl amine (DMBA) with 1-octanol (D1), 1-nonanol (D2), and 1-decanol (D3) were performed across temperatures from 303.15 K to 313.15 K under atmospheric pressure, covering all composition ranges. These experimental results were utilised to calculate the excess molar volume, excess isentropic compressibility, viscosity deviation, and the excess Gibbs free energy of activation for viscous flow. Calculations for partial molar properties and infinite dilution partial molar properties were also carried out for each binary mixture. The dominant intermolecular interactions within these mixtures were analysed using the PFP theory. Additionally, the Jouyban−Acree model was applied to predict the thermo physical properties such as density, speed of sound, and viscosity. The model’s accuracy was evaluated by comparing predicted values with experimental data through mean relative deviations (MRDs) and individual relative deviations (IRDs).

Exploring the Role of Titanate Perovskites in the Oxidation of Amines to Imines via Photocatalysis.

Considering that structural differences could affect the photocatalytic efficiency of titanate perovskites, cubic SrTiO3 (STO) and tetragonal CaTiO3 (CTO) were synthesised as models to elucidate the structure-activity relationship. STO and CTO materials were produced through hydrothermal approaches, adjusting parameters such as temperature and pressure to optimise material purity. Among the perovskite photocatalysts, two stand out for their exceptional photocatalytic capacity and crystalline purity: CaTiO3, prepared at 180 ºC for 36 h, and SrTiO3, synthesised at 200 ºC for 24 h. Notably, we explore the selective ability of these materials for the photocatalytic oxidative self-coupling of benzylamine (BZA) to produce N-benzylidenebenzylamine (BZI), with CaTiO3 emerging as the most efficient catalyst for this reaction. The CTO material prepared at 180 ºC for 36 h (CTO180T-36) achieved a peak BZI production of 0.5 mM, with a total conversion of BZA after 7 h of irradiation. This study also emphasises the crucial role of reaction conditions and perovskite morphologies in fine-tuning photocatalytic performance. These findings highlight opportunities for developing efficient and selective photocatalytic processes, holding the compromise for applications in organic synthesis and sustainable green chemistry.

One-pot synthesis of carbon dots/hydrochar and visible-light-driven photocatalysts for aerobic oxidative coupling of benzylic amines

Utilizing selective photocatalysis conversion of amines represents an environmentally sustainable and economically feasible approach to generating valuable chemical products in the industry. Herein, carbon dots (CDs) incorporated in hydrochar (CDs/HCPP) were synthesized by one-pot hydrothermal carbonization of pomelo peel (PP) coupled with freeze-drying and used for aerobic oxidative coupling of benzylic amines. CDs were produced using only the pomelo peel as the carbon source, without the addition of any extra carbon additives. CDs/HCPP exhibited the greatest catalytic activity, achieving a benzylamine conversion rate of 99%, which was nearly 5.5 times of carbonized PP (CPP) without CDs and 1.14 times of CDs alone. Additionally, the oxidation of other amines, such as p -substituted benzylamines with groups that donate and withdraw electrons, was also demonstrated to be highly active and reusable using CDs/HCPP. This study has the potential to pave the way for novel methodologies and insights into synthesizing biomass composites adorned with CDs, enhancing the efficacy of photocatalytic syntheses.

Thermodynamic and spectroscopic analyses of N-Methyl benzylamine-isomeric amyl alcohol binary mixtures: Jouyban-Acree model correlation and experimental validation

ABSTRACT Excess molar volume, excess isentropic compressibility, deviation in viscosity, and excess Gibbs free energy of activation for viscous flow for binary mixtures of N-Methyl benzyl amine (NMBA) with 2-Methyl-2-butanol (2M2B), 2-Methyl-1-butanol (2M1B), and 3-Methyl-1-butanol (3M1B) were determined from measured densities (ρ), viscosities (η) and speeds of sound (u) at 303.15 K to 313.15 K. Influence Structural disparities on excess properties is discussed concerning intermolecular forces. The Prigogine – Flory – Patterson (PFP) theory identifies predominant molecular interactions, and the Jouyban – Acree model correlates density, speed of sound, and viscosity with composition. Thermodynamic activation parameters were calculated using the Eyring equation to study viscous flow thermodynamics. FT-IR and 1H NMR spectra of equimolar binary mixtures were analysed to confirm experimental findings through absorption bands (cm−1) and chemical shifts.

Selective adsorption behaviors and mechanisms of benzyl quaternary ammonium salt on quartz and gypsum: A combined experimental and theoretical study

Benzyl quaternary ammonium salt is an effective collector of quartz from gypsum. To investigate the selective collection mechanism of tetradecyl dimethyl benzyl ammonium chloride (TDBAC) for quartz from a microscopic view, the adsorption experiments, first-principles calculations based on density functional theory (DFT), and molecular dynamics (MD) simulation were performed in this work. The adsorption experiment results show that the adsorption capacity of TDBAC on the quartz surface was 1.6 × 10−6 mol/m2, much larger than that on the gypsum surface (1.0 × 10−7 mol/m2). The interaction energy of TDBAC with quartz surface was −20202.98 kJ/mol, much smaller than that with gypsum surface (-78.37 kJ/mol). DFT calculation results indicate that the quartz surface was more likely to interact with TDBAC through electrostatic attraction since the average negative charge and exposure oxygen density of the quartz surface were both greater than those of the gypsum surface. After the adsorption of TDBAC, there were hydrogen bonds formed between the hydrogen atoms in TDBAC and the oxygen atoms on the quartz surface. This work confirmed that the highly selective adsorption of TDBAC on quartz surface was attributed to the strong electrostatic attraction and hydrogen-bond interaction.

Base‐Catalyzed Decarboxylative Amination of In‐Situ Generated Ortho‐Quinone Methides: Synthesis of Benzyl Amines

AbstractIn this paper, a direct access to benzylic amines from in‐situ generated ortho‐quinone methides (o‐QMs) and isocyanate/isothiocyanate via decarboxylation is described. This base‐catalyzed methodology has high functional group tolerance and shows a wide range of substrate scopes, where H2O as a nucleophile for isocyanate/isothiocyanate for product formation. The products are insensitive to air and moisture, which makes this synthetic strategy more efficient for the construction of various benzyl amine derivatives.

Unveiling Alternate Electrode Electrolysis in Electro-Photochemical and Electro-Organic Syntheses.

Electro-photochemical organic synthesis is a rapidly growing field. Recently, technological advancement has contributed significantly to improve electro- and photolytic organic transformations in terms of energy efficiency and productivity. Herein, we have introduced alternating electrode electrolysis|alternate electrode electrolysis (AEE), a new technique in electrosynthesis which in combination with blue LED demonstrated an interesting three-component reaction with aryl diazoesters, 1,4-quinones, and acetone to synthesize ketal-functionalized 1,4-quinones. The AEE setup consists of two pairs of cathode-anode compared to the conventional setup of one pair. Each pair would be polarized or in a resting stage with a preset interval of choice. This would maintain a continuous potential resulting in maximum current and would facilitate the mass transport, thereby increasing the overall efficiency of the reaction. AEE offers the efficient utilization of photochemically generated carbenes. We extended AEE applications in paired photoelectrolysis reactions for the late-stage functionalization of bioactive molecules and pharmaceutical agents. As an application of AEE in electrosynthesis (without light), we demonstrated the efficient hydroxylation of fluorinated benzene and the reduction of benzonitrile to benzyl amine. The amalgamation of AEE with blue LED contributes to sustainability, and we believe that it holds great promise in the field of electro-photochemical organic synthesis.

High-performance removal of methylene blue dye using porous lignin extracted from sugarcane bagasse by deep eutectic solvent

This study evaluated the ability of triethyl benzyl ammonium chloride/lactic acid deep eutectic solvent extracted lignin (TEBAC/LA-DES-L) to adsorb methylene blue (MB) without additional functional group modification. The structure and morphology of TEBAC/LA-DES-L were characterized using SEM, BET, FT-IR, and TGA techniques. Various factors influencing MB adsorption, such as extraction temperature, solution pH, adsorbent dose, initial MB concentration, adsorption time, and reaction temperature, were investigated. The Redlich-Peterson isotherm displayed a good fit for the experimental data, with a maximum adsorption capacity of 85.16 mg/g. Kinetic analysis suggested that the adsorption process followed the pseudo-second-order model, with adsorption occurring in <100 min on DES-L-4 h. The mechanism of MB adsorption on DES-L-4 h was attributed to electrostatic attraction, hydrophobic interactions, and hydrogen bonding forces. Overall, DES-L-4 h demonstrated high adsorption capacity and rapid adsorption rate, making it a promising adsorbent for effectively removing cationic dyes from wastewater.

(Diethylamino)sulfur trifluoride (DAST)-mediated oxidation of benzylic alcohols and amines to carbonyl compounds

We report an efficient protocol for oxidation of primary/secondary benzyl alcohols and benzylamines to produce corresponding aldehydes or ketones. Our unified method involves the use of commercially available (diethylamino)sulfur trifluoride (DAST) as a reagent combined with DMSO as solvent and oxidant. The reaction provided corresponding carbonyl compounds in good to excellent yields with high purity and in short reaction times.

Electrocatalytic Anaerobic Oxidation of Benzylic Amines Enabled by Ferrocene-Based Redox Mediators

Electrocatalytic Anaerobic Oxidation of Benzylic Amines Enabled by Ferrocene-Based Redox Mediators

Atomic Electrostatic Potential as a Descriptor of Aminolysis of Phenyl and Thiophenyl Acetates and Hydrolysis of Acetanilides

Abstract: Hydrolysis of acetanilides and aminolysis of phenyl and thiophenyl acetates are related reactions since these are processes of nucleophilic substitution on the carbonyl carbon. Current views of chemical reactivity based on the DFT theory rely upon reactivity indices that are descriptors of both the reaction center and the molecule as a whole, and have not been applied to the given processes before. One of such descriptors is an atomic electrostatic potential. The given parameter was calculated by the DFT theory M06/6-311+G (non-specific solvation, MeCN, SMD, and full optimization) for the structures of substituted phenyl acetates XPhO-C(O)Me, acetanilides XPhNHC(O)Me, thiophenyl acetates ZPhSC(=O)Me, and benzyl amines XPhСH2NH2 (X, Z substituents). It has been found that all relationships between the atomic electrostatic potential, the charge on the reaction center in the Hirshfeld scheme, and logK are symbatic. Consequently, in all of the cases, the rate is determined by the nucleophilic attack on the reaction center, with the activity/selectivity relationship being observed. The fact that the reaction rate is limited by the nucleophilic attack of the reagent is not inconsistent with the views of the reaction being concerted, since it is known that such reactions may be quite concerted though not quite synchronous.

Cellulose-based colorimetric/ratiometric fluorescence sensor for visual detecting amines and anti-counterfeiting

Many amines with high toxicity always cause a serious threat to the ecological environment and human health; thus, their detection is important. Herein, a dual-mode colorimetric and ratiometric fluorescent sensor based on cellulose for detecting amines has been constructed by a new strategy. This sensor is made of a “negative response” indicator (Lum-MDI-CA) and a “positive response” indicator (perylene tetracarboxylic acid, PTCA). Lum-MDI-CA was obtained by attaching luminol onto cellulose chains, which emitted blue fluorescence and was quenched upon contact with amines. A possible mechanism of fluorescence quenching phenomenon is proposed by the intramolecular charge transfer (ICT) of Lum-MDI-CA. Subsequently, by simply mixing Lum-MDI-CA with PTCA, a dual-mode fluorescence sensor was designed for visual detection and classification of amines. When adding ammonia (NH3), morpholine (MOR), benzylamine (BNZ), diethylamine (DEA), and triethylamine (TEA), respectively, the dual-mode sensor showed visible different color changes under both UV light and daylight. In addition, owing to the excellent processibility and formability of cellulose acetate backbone, the prepared sensor can be easily processed into different material forms, including inks, coatings, films, and fibers, which still exhibit excellent fluorescence emission. Such sensors based on cellulose fluorescent materials are of great value in anti-counterfeiting and information encryption.

Structural Ni0-Niδ+ Pair Sites for Highly Active Hydrogenation of Nitriles to Primary Amines.

Supported metal pair sites have sparked interest due to their tremendous potential as bifunctional catalysts. Here, we report the structural Ni0-Niδ+ pair sites constructed in a well-defined nanocrystal phase of Ni3P. These Ni0-Niδ+ pair sites exhibited a remarkable product formation rate of 123 molBA/molmetal/h for the hydrogenation of benzonitrile (BN) to benzylamine (BA). The heterogeneity of surface Ni atoms over the Ni3P crystal created two types of metal centers, Ni0 and Niδ+, with a specific spatial distance of 4-5 Å. The Ni0 site acted as the center for H2 activation, while the Niδ+ site served as the adsorption and activation center for the C ≡ N group. The highly efficient cooperation effect of Ni0-Niδ+ pair sites resulted in a TOF of 2915 h-1 in BN hydrogenation, which is 2.4 and 9.7 times higher than that over the mono-Ni0 and -Niδ+ sites, respectively.

Active site modulation in UiO-66(Ce) MOFs by Al3+ doping for boosting photocatalysis

A series of Al3+-doped UiO-66(Ce) MOFs (U(CexAl1−x)) was developed to reveal the roles of metal doping on active site formation and substrate activation in photocatalytic selective transformation of amines to imines. Al3+ doping induced crystal structure distortion to form coordinately unsaturated metal (Al, Ce) sites as Lewis acid sites to chemisorb and activate benzylamine (BA). In situ FTIR revealed that the Al site with stronger acid strength facilitated BA activation. The activation degree of N–H bonds in BA was evaluated by changes of calculated force constant. The intermediate products were confirmed through time-dependent in situ FTIR. The Al3+-doped sample U(Ce0.90Al0.10), the optimal catalyst, showed a significantly increased BA conversion (97.6 %) than that (47.5 %) of undoped sample, which was attributed to enough active sites and the optimal charge mobility. Finally, the present study proposes a synergistic photocatalytic mechanism associated with molecular activation to demonstrate selective oxidation pathways at the molecular level.

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.

Synthesis of hexafluorovaline-containing di- and tripeptides

A new strategy for the synthesis of peptides incorporating racemic hexafluorovaline (hfVal) is presented. The synthetic pathway relies on the anti-Michael addition of benzyl amine derivatives to ad hoc prepared β-bis-trifluoromethyl-acryloyl-α-amino esters which proceeds in mild condition, high yields, even if with low stereocontrol. The following elaboration of the intermediates, namely deprotection of the benzyl moiety and coupling with α-amino esters allowed us to synthetize the targeted tripeptides in four overall synthetic steps, resulting in a synthetic pathway more favorable respect to those appeared in literature based on the synthesis and isolation of racemic Boc-hfVal-OH (eight synthetic steps).

Tuning the Selectivity of Catalytic Nitrile Hydrogenation with Phase-Controlled Co Nanoparticles Prepared by Hydrosilane-Assisted Method.

Cobalt (Co) is a promising candidate to replace noble metals in the hydrogenation process, which is widely employed in the chemical industry. Although the catalytic performance for this reaction has been considered to be significantly dependent on the Co crystal phase, no satisfactory systematic studies have been conducted, because it is difficult to synthesize metal nanoparticles that have different crystalline structures with similar sizes. Here we report a new method for the synthesis of cobalt nanoparticles using hydrosilane as a reducing agent (hydrosilane-assisted method). This new method uses 1,3-butanediol and propylene glycol to successfully prepare fcc and hcp cobalt nanoparticles, respectively. These two types of Co nanoparticles have similar sizes and surface areas. The hcp Co nanoparticles exhibit higher catalytic performance than fcc nanoparticles for the hydrogenation of benzonitrile under mild conditions. The present hcp Co catalyst is also effective for highly selective benzyl amine production from benzonitrile without ammonia addition, whereas many catalytic systems require ammonia addition for selective benzyl amine production. Mechanistic studies revealed that the fast formation of the primary amine and the prevention of condensation and secondary amine hydrogenation promote selective benzonitrile hydrogenation for benzylamine over hcp Co nanoparticles.