Toluene Ring Research Articles

Preparation of Cs/CuAl-LDO@Al2O3@Fe3O4 magnetic catalysts and reaction mechanism of the side-chain alkylation of toluene to styrene

A series of Cs/CuAl-LDO@Al2O3@Fe3O4 magnetic catalysts with varied CuAl-LDO contents were prepared by growing CuAl-LDH layers on the surface of Al2O3@Fe3O4 magnetic cores, impregnated with Cs and followed by calcination. The as-synthesized catalysts were characterized by XRD, N2 adsorption-desorption, SEM, TEM(EDS), XPS, NH3-TPD, CO2-TPD, and VSM techniques. The catalytic performance and reusability of the catalysts for the side-chain alkylation of toluene with formaldehyde were evaluated in a micro-high-pressure reactor, and the reaction mechanism was further studied. The results showed that the Al2O3@Fe3O4 magnetic core of the catalyst was about 110 nm, and the CuAl-LDO formed a staggered lamellar structure with a shell thickness of around 30–45 nm. The magnetic catalyst demonstrated excellent catalytic performance and reusability for the side-chain alkylation of toluene with formaldehyde in one-step to styrene. As-synthesized magnetic Cs/CuAl-LDO@Al2O3@Fe3O4 catalyst with CuAl-LDO content of 20 wt% delivered toluene conversion of 7.97% under optimized conditions, while the styrene selectivity and the selectivity of side-chain alkylation were 90.17% and 98.36%, respectively. The reaction mechanism showed that the benzene ring of toluene was stably adsorbed on the Al3+ acid sites of the CuAl-LDO layers. The C–H group of the side-chain of toluene formed carboanions and protons under the action of the Cuδ+–Oδ– base sites. Formaldehyde formed a transition state of adsorbed formaldehyde under the action of Cuδ+ acid sites. Finally, these adsorbed states and intermediate species accomplished the side-chain alkylation of toluene with formaldehyde to styrene in one-step under the synergic action of acid-base sites. The synergistic effects of suitable acid-base sites and lamellar spatial structures in the catalyst were the key to styrene formation with high selectivity.

Molecular dynamics investigation of the interaction between volatile organic compounds and deep eutectic solvents

ABSTRACTMixtures of tetrabutylammonium-chloride-based deep eutectic solvent (DES) and three volatile organic compounds (VOCs) – butanal, ethanol, and toluene – have been investigated using classical molecular dynamics simulations. Various structural analyses like radial and spatial distribution functions reveal the presence of specific interactions between DES components and VOCs. The interaction between the VOC and DES components depends on the nature of the former. Both ethanol and butanal have an H-bond interaction with chloride and ethylene glycol. Tetrabutylammonium cations are present above and below the ring of toluene due to the presence of π electron cloud, and toluene also forms π hydrogen bonds with ethylene glycol. The structure of DES is not significantly affected by the absorption of VOCs, which is reflected in their radial distribution functions. Components of DES become more mobile with the addition of VOCs. The interfacial region was found to be the most favourable location for the presence of VOCs.

Crystal structure of N-[3-(benzo[d]thia-zol-2-yl)-6-bromo-2H-chromen-2-yl-idene]-4-methyl-benzenamine.

The title compound, C23H15BrN2OS, was the unexpected product in an attempted synthesis of the isomeric 3-(benzo[d]thia-zol-2-yl)-6-bromo-1-p-tolyl-quinolin-2(1H)-one. The Cchromene=N-C angle is wide [125.28 (8)°]. The benzo-thia-zole and chromene ring systems are almost coplanar, with their planes parallel to (10); the toluene ring system is rotated by ca 40° out of the chromene plane. The mol-ecular packing involves layers with π-stacking, borderline 'weak' hydrogen bonds and possible C-H⋯π contacts.

Chain Walking in the AlCl3 Catalyzed Cationic Polymerization of α-Olefins.

Continuing efforts aimed at performing the 1-decene polymerization to low viscosity polyalphaolefins (PAO)s using a less hazardous AlCl3 catalyst than boron-based analogs, the basic mechanisms of this system were revealed in this research. In this aspect, neat AlCl3 and AlCl3 /toluene were carried out to perform 1-decene polymerizations. Microstructure analyses of the as-synthesized oils revealed low molecular weight (708 vs. 1529 g/mol), kinematic viscosity (KV100 =6.4 vs. 22.2 cSt), and long chain branching (82.1 vs. 84.7) of PAO from the system containing toluene solvent. Furthermore, NMR analysis confirmed various types of short chain branch (SCB) with the inclusion of toluene ring in the structure of final PAO chains. Then, to shed light on the basic mechanisms of cationic polymerization of 1-decene including: i) chain initiation, ii) chain transfer to the monomer, iii) isomerization of the carbocation via a chain walking mechanism (causes different SCB length), and iv) binding of toluene ring to the propagating PAO chain (to yield aromatic containing oligomers), molecular modeling at the DFT level was employed. The energies obtained confirmed the ease of carbocation isomerization and chain transfer mechanisms in toluene medium, which well confirms the highly branched structure experimentally obtained for related PAO.

Crystal structure and Hirshfeld surface analysis of N-{[5-(4-methyl-phen-yl)-1,2-oxazol-3-yl]meth-yl}-1-phenyl-N-(prop-2-en-1-yl)methane-sulfonamide.

In the title compound, C21H22N2O3S, the 1,2-oxazole ring makes the dihedral angles of 9.16 (16) and 87.91 (17)°, respectively, with the toluene and phenyl rings, while they form a dihedral angle of 84.42 (15)° with each other. The C-S-N-Cpr and C-S-N-Cme (pr = propene, me = 3-methyl-1,2-oxazole) torsion angles are 86.8 (2) and -100.6 (3) °, respectively. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds, generating a three-dimensional network. A Hirshfeld surface analysis was performed to investigate the contributions of the different inter-molecular contacts within the supra-molecular structure. The major inter-actions are H⋯H (53.6%), C⋯H/H⋯C (20.8%) and O⋯H/H⋯O (17.7%).

Interactions between methanol/toluene binary mixtures and an organic solvent nanofiltration PIM-1 membrane

In this work, a molecular scale study of the interactions between a polymer with intrinsic microporosity (PIM-1) membrane and toluene, methanol and their mixtures was performed by means of molecular dynamics simulations. From the radial distribution functions we highlight specific interactions between the hydroxyl group of methanol and the aromatic ring of toluene as well as with the PIM-1 membrane. Moreover, the presence of nitrogen atoms on the PIM-1 backbone makes it possible the formation of hydrogen bonds like interaction (close contact of 2.5 Å) between the methanol molecules and the PIM-1 membrane, thus leading to interfacial anchoring of methanol at the polymer surface and moving toluene molecules away from the surface. However some toluene molecules are located around 3.5 Å due to π-stacking interaction between the aromatic rings of the PIM-1 membrane and those of the confined TOL molecules. At short range, the confined methanol molecules interact with each other like their bulk-phase counterparts whereas long range correlations highlight a existence of confined methanol aggregates. The specific interactions between toluene, methanol and the PIM-1 membrane result in a linear increase of the membrane swelling with the mole fraction of toluene in the binary mixtures.

13-Benzyl-4,11-dihy-droxy-1,8-diphen-yl-2,9-di-thia-13-aza-dispiro-[4.1.4.3]tetra-decan-6-one.

In the title compound, C30H31NO3S2, the piperidine ring adopts a distorted chair conformation. The thio-phene rings have twisted conformations about the C-C bonds. The mean plane of the piperidine ring makes a near orthogonal conformation with the toluene ring. Two of the phenyl rings in the structure are positionally disordered over two sets of sites with occupancies of 0.56 (2)/0.44 (2) and 0.672 (16)/0.328 (16). A region of disordered electron density was corrected for using the SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9-18] routine in PLATON. The given chemical formula and other crystal data do not take into account the unknown solvent mol-ecule. In the crystal, O-H⋯O hydrogen bonds are observed along with intra-molecular S⋯H, O⋯H, C⋯H and H⋯H contacts.

Zn-doping mediated formation of oxygen vacancies in SnO2 with unique electronic structure for efficient and stable photocatalytic toluene degradation

To optimize the electronic structure of photocatalyst, a facile one-step approach is developed for the simultaneous realization of Zn-doping and surface oxygen vacancies (SOVs) formation on SnO2. The Zn-doped SnO2 with abundant SOVs exhibits efficient and stable performance for photocatalytic degradation of toluene under both low and high relative humidity. Experimental and theoretical calculations results show that the synergistic effects of Zn-doping and SOVs on SnO2 can considerably boost the charge transfer and separation efficiency. Utilizing the in situ DRIFTS and theoretical calculations methods, it is revealed that the benzene ring of toluene is opened at benzoic acid on the SnO2 surface and selectively at benzaldehyde on the Zn-doped SnO2 surface. This implies that Zn-doped SnO2 photocatalysts shorten the pathway of toluene degradation, and toxic intermediates can be significantly inhibited. This work could provide a promising and sustainable route for safe and efficient removal of aromatic VOCs with photocatalytic technology.

A density functional theory study on the interaction of toluene with transition metal decorated carbon nanotubes: a promising platform for early detection of lung cancer from human breath

In this study, single-wall carbon nanotubes (SWCNTs) decorated by platinum-group transition metals (Pt, Pd, Rh, or Ru) were introduced as promising nanosensors for the detection of toluene, an important biomarker in the exhaled breath of the lung cancer patients. First-principle calculations based on density functional theory (DFT) was employed to scrutinize the impact of an individual toluene gas molecule on the structural, electronic, and magnetic properties of pristine and metal decorated SWCNTs. It was discovered that toluene is physisorbed on the pristine SWCNT through the interaction of the π orbitals of the carbon atoms in the toluene and the nanotube. Decoration of the SWCNT with metal atoms enhanced the adsorption energies significantly by means of strong overlapping between d orbital of the metal atoms and p orbital of C atoms in the benzene ring of toluene. Investigations showed that toluene is strongly chemisorbed on Rh- and Ru-SWCNT systems via strong covalent bonds with the superior response (−96.98% and −99.98%, respectively), and moderately chemisorbed on Pt-SWCNTs (−27.3%) and Pd-SWCNTs (61.60%). Our findings propose metal decorated SWCNT molecular sensors are attractive candidates for the detection of toluene and other lung cancer biomarkers in the exhaled breath of the lung cancer patients.

Delocalization Effect Promoted the Indoor Air Purification via Directly Unlocking the Ring-Opening Pathway of Toluene

The ring-opening process was generally considered as the rate-determining step for aromatic volatile organic compound photocatalytic degradation. A sophisticated and intensive degradation pathway is critical to the poor removal efficiency and low mineralization. In the present contribution, we successfully tailored and identified the ring-opening pathway of toluene elimination by electron delocalization in a borocarbonitride photocatalyst. By means of modulation of the dopant coordination configuration and electron geometry in the catalyst, the lone electrons of carbon transform into delocalized counterparts, sequentially elevating the interaction between the toluene molecules and photocatalyst. The aromatic ring of toluene can be attacked directly in the effect of electron delocalization without engendering additional intermediate species, significantly facilitating the removal and mineralization of toluene. This unprecedented route-control strategy alters the aromatic-ring-based reaction behavior from toluene to CO2 and paves a way to purify the refractory pollutants from the top design.

Crystal structure and Hirshfeld surface analysis of 4-(4-methyl-benz-yl)-6-phenyl-pyridazin-3(2H)-one.

In this paper, we describe the synthesis of a new di-hydro-2H-pyridazin-3-one derivative. The mol-ecule, C18H16N2O, is not planar; the benzene and pyridazine rings are twisted with respect to each other, making a dihedral angle of 11.47 (2)°, and the toluene ring is nearly perpendicular to the pyridazine ring, with a dihedral angle of 89.624 (1)°. The mol-ecular conformation is stabilized by weak intra-molecular C-H⋯N contacts. In the crystal, pairs of N-H⋯O hydrogen bonds link the mol-ecules into inversion dimers with an R 2 2(8) ring motif. The inter-molecular inter-actions were investigated using Hirshfeld surface analysis and two-dimensional (2D) fingerprint plots, revealing that the most important contributions for the crystal packing are from H⋯H (56.6%), H⋯C/C⋯H (22.6%), O⋯H/H⋯O (10.0%) and N⋯C/C⋯N (3.5%) inter-actions.

Metal Cocatalyst Directing Photocatalytic Acetonylation of Toluene via Dehydrogenative Cross-Coupling with Acetone

A heterogeneous metal-loaded titanium oxide photocatalyst provided an efficient route to bring out direct dehydrogenative cross-coupling between toluene and acetone without consuming any additional oxidizing agent. The nature of the metal nanoparticle cocatalyst deposited on TiO2 photocatalyst dictated the product selectivity for the cross-coupling. Pd nanoparticles on TiO2 photocatalyst allowed a C–C bond formation between the aromatic ring of toluene and acetone to give 1-(o-tolyl)propan-2-one (1a1) with high regioselectivity, while Pt nanoparticles on TiO2 photocatalyst promoted the cross-coupling between the methyl group of toluene and acetone to give 4-phenylbutan-2-one (1b) as the acetonylated product. These results demonstrated that the selection of the metal cocatalyst on TiO2 photocatalyst could determine which C–H bonds in toluene, aromatic or aliphatic, can react with acetone. Two kinds of reaction mechanisms were proposed for the photocatalytic dehydrogenative cross-coupling reaction, depending on the property of the metal nanoparticles, i.e., only Pd nanoparticles can catalyze the reaction between aromatic ring and the acetonyl radical species.

Synthesis, crystal structure and Hirshfeld surface analysis of a benzoxazole derivative [2-[2-(4-Methylphenyl)ethenyl]-1,3-benzoxazole

Abstract Benzoxazole nucleus is one of the most important heterocyclic compounds exhibiting remarkable pharmacological activities such as antibacterial activity, antifungal activity, Anticonvulsant activity, etc., In view of the importance of benzoxazole derivative we synthesized one benzoxazole derivative, their structural and Hirshfeld Surface were analyzed. The Single crystal x-ray diffraction analysis reveals that the compound 2-[2-(4-Methylphenyl)ethenyl]-1,3-benzoxazole crystallizes in monoclinic system with space group P21/n. The oxazole and the toluene rings are almost in planar conformation. The dihedral angle between the oxazole ring and toluene ring is 9.49(6)°. The crystal packing is stabilized by intramolecular C H…O type of hydrogen bonds. In Additional to that, the crystal packing is stabilized by van der Waals forces.

Hydrogenation of the Liquid Organic Hydrogen Carrier Compound Monobenzyl Toluene: Reaction Pathway and Kinetic Effects

AbstractLiquid organic hydrogen carriers (LOHCs) are an interesting option for storing hydrogen through a reversible chemical reaction. The catalytic hydrogenation reaction was studied for the carrier material monobenzyl toluene. GC analysis was used to quantify the components occurring in a complex reaction mixture. It was shown that the hydrogenation reaction proceeds predominantly by stepwise hydrogenation of the aromatic ring. As the molecular structure of monobenzyl toluene is formally the combination of a xylene and a toluene ring, two possible reaction pathways have been evaluated: hydrogenation of the mono‐substituted side ring (toluene) and di‐substituted main ring (xylene). Intermediates for both pathways were detected during the reaction. Concerning the isomeric structure of benzyl toluene, the fastest hydrogenation was observed for the para species. Isomeric mixtures were hydrogenated the slowest.

Black NiO-TiO2 nanorods for solar photocatalysis: Recognition of electronic structure and reaction mechanism

This work provides an engineering guide to construct active sites on TiO2 nanorods (NRs) by coupling p-type black NiO nanoclusters (Eg=1.42eV) with rich crystal defects and match-up band structure for excellent solar photocatalysis. Photo-oxidation of toluene was used as a model reaction to evaluate the photocatalytic performance of black NiO/TiO2 hybrids under simulated solar light irradiation from a 300W Xe-lamp. The black NiO/TiO2 hybrids Exhibit 80% of photodegradation conversion and 56% of mineralization efficiency, which are 7.9 and 4.5 times higher than those of TiO2 NRs. Detailed characterizations reveal that highly dispersed NiO and p-n heterojunction effectively facilitate light-harvesting, separation and transfer of photo-generated charge carries, and significantly inhibit the recombination of electrons and holes. Furthermore, the realignment of band structure and the p-n heterojunctions in NiO/TiO2 result in the production of O2− and h+ with a longer lifetime, which could efficiently attack the aromatic ring of toluene. The efficient adsorption of toluene by H-bonding formation also facilitates the photo-oxidation of toluene on NiO/TiO2.

Biphenyl-4-yl 4-methylbenzenesulfonate

Molecules of the title compound, C19H16O3S, are composed of a biphenyl moiety substituted with a toluene-4-sulfonate group. The dihedral angle between the two coplanar biphenyl rings and the toluene ring is 52.72 (6)°.

Investigation of Lewis Acid-Base Reaction of Acidic Species Present in Aluminum Chloride-Urea Ionic Liquid [AlCl2.nUrea] +

Aluminum chloride-urea ionic liquid was investigated for its active species concentration with the aide of electronic spectroscopy by Lewis acid-base titration with chloride ions. A coordination bonds between aluminum cationic species of the ionic liquid and the aromatic ring of toluene or benzene was assumed to be responsible for new formed bands in visible and ultraviolet regions. Upon Lewis acid-base titration these bands disappeared and the concentration of the acidic species were elucidated to be around 75 mole% of the initial aluminum chloride used to prepare a 1.5 mole aluminum chloride to 1 mole urea ionic liquid. The product of this reaction assumed to be between 1 acidic species to 1 chloride ion according to the mole fraction elucidated graph.

(Z)-3-(4-Methylbenzylidene)-4-oxopentanoic acid

The title compound, C13H14O3, a levulinic acid derivative, crystallizes with two independent molecules (AandB) in the asymmetric unit. The compound adopts aZconfiguration about the C=C bonds in both molecules. The dihedral angle between the toluene ring and the carboxylic acid group is 72.83 (7)° in moleculeAand 83.64 (8)° in moleculeB. The toluene rings are inclined to the ketone substituents by 27.03 (9)° forAand 30.84 (6)° forB. In the crystal, like molecules are linked by pairs of O—H...O hydrogen bonds, formingA–AandB-Binversion dimers.

Ethyl 3-methyl-1-phenyl-5-(p-tolyl)-1H-pyrazole-4-carboxylate

In the title compound, C20H20N2O2, the pyrazole ring makes dihedral angles of 39.74 (8) and 60.35 (8)° with the phenyl and toluene rings, respectively. The dihedral angle between the phenyl and toluene rings is 62.01 (7)°.

N′-[(E)-4-Methoxybenzylidene]-2-(4-methylphenoxy)acetohydrazide

The title compound, C17H18N2O3, crystallizes with two independent molecules (AandB) in the asymmetric unit. The dihedral angle between the 4-methoxyphenyl ring and the toluene ring is 88.13 (10)° in moleculeAand 61.47 (10)° in moleculeB. In the crystal, molecules are linkedviapairs of N—H...O hydrogen bonds, formingA–AandB–Binversion dimers withR22(8) ring motifs. TheB–Bdimers are linked by C—H...O hydrogen bonds, forming chains propagating along the [110] direction. The molecules are also linked by a series of C—H...π interactions, forming a three-dimensional structure.