Analysis of Pyridine, Picoline and Lutidine’s Adsorption Behavior on The Al (111)-lattice

The reactivity and adsorption behavior of five organic inhibitors of pyridine and its derivatives of 2-picoline, 3-picoline, 4-picoline, and 2,4-lutidine at the Al(111) lattice in hydrochloric acid was studied by the principle of the HF and B3LYP level using the 6-31G and LANL2DZ basis sets from the program package gaussian 03. The compound was adsorbed on the metal lattice based on the calculated results, mainly in their protonated forms. In the Al (111)-lattice, the charge is transferred to the inhibitor, and the organic inhibitor is adsorbed at the Al (111)-lattice in an inclined state. The quantum chemical calculations of molecular reactivity show that the frontier orbitals of the four additives are distributed around the nitrogen atom of the pyridine ring, the aluminum atom of Al (111)-lattice, and active electrophilic centers are located on the nitrogen atoms of the pyridine ring. All five molecules were adsorbed with the chemical adsorption on the Al (111)-lattice, and the order of adsorption was 2-picoline>2, 4-lutidine> 4-picoline> 3-picoline> pyridine. The N atoms of four derivatives form N-Al bonds with the Al atoms of the Al (111)-lattice, which makes derivatives stably adsorb on the Al lattice.

Density Functional Theory Study of the Adsorption of Metal Adatoms on Graphene

In this study, we investigated the influence of the interaction between graphene and other materials as a basis for controlling the electronic structure of nanocarbon materials. First-principles calculations based on density functional theory (DFT) were performed on the optimized structure, adsorption energies and electronic states when copper and aluminum atoms were placed on graphene. As a result, we found that copper and aluminum are stable at the bridge and the hollow site, respectively. It was found that the adsorption energy of aluminum atom on graphene is larger than that of copper atom. It is considered that the difference in adsorption energy is caused by the difference in the dominant electron orbitals of the copper atom and the aluminum atom.

Selective synthesis of spirobiindanes, alkenyl chlorides, and monofluoroalkenes from unactivated gem-difluoroalkanes controlled by aluminum-based Lewis acids

The highly selective synthesis of spirobiindanes, alkenyl chlorides, and monofluoroalkenes via the cleavage of inert C(sp3)–F bonds in unactivated gem-difluoroalkanes using readily available and inexpensive aluminum-based Lewis acids of low toxicity is reported. The selectivity of this reaction can be controlled by modifying the substituents on the central aluminum atom of the promoter. An intramolecular cascade Friedel-Crafts alkylation of unactivated gem-difluorocarbons can be achieved using a stoichiometric amount of AlCl3. The subsequent synthesis of alkenyl chlorides via F/Cl exchange followed by an elimination can be accomplished using AlEt2Cl as a fluoride scavenger and halogen source. The defluorinative elimination of acyclic and cyclic gem-difluorocarbons to give monofluoroalkenes can be achieved using AlEt3.

Comparison of Lewis Acidity between Al-MCM-41 Pure Chemicals and Al-MCM-41 Synthesized from Bentonite

This study focused on the Lewis acidity of Al-MCM-41 prepared from bentonite (Al-MCM-bentonite) as silica and aluminum source simultaneously. This acidity was compared with Al-MCM-41 synthesized from pure chemicals reagents (Al-MCM-standard). Structural analysis showed that the substitution of the silicon atom by the aluminum atom decreases the structural order of Al-MCM-standard, whereas Al-MCM-bentonite has a better structural organization. The Lewis acidity of the Al-MCM-bentonite was evaluated in allylation reaction of benzaldehyde with allyltrimethylsilane and pyridine adsorption experiments. The results showed that the difference in acidity between Al-MCM-standard and Al-MCM-bentonite is due to the amount of aluminum incorporated into the framework of our mesoporous materials. According to the EDX analysis, the incorporation of aluminum in Al-MCM-standard (Si/Al = 13.47) is more important than in Al-MCM-bentonite (Si/Al = 43.64). This explains the low acidity of Al-MCM-bentonite, and the moderate yields in the allylation reactions of benzaldehyde with allyltrimethylsilane. Copyright © 2019 BCREC Group. All rights reserved

Влияние водорода на флуктуационное охрупчивание алюминия

The main processes occurring during vacancy generation in aluminum in the presence of hydrogen are described on the base of ab initio methods using the meta-functional SCAN. It was shown that hydrogen reduces the vacancy generation energy from 2.8 eV to 0.8 eV. In this case, eight hydrogen atoms located in the tetrahedral voids of the lattice around one aluminum atom make it much easier for it to move to the interstitial site. In accordance with the kinetic concept of embrittlement the dependence of the activation energy of hydrogen embrittlement of aluminum is calculated on the concentration of hydrogen and temperature. It is shown that hydrogen reduces the time of aluminum embrittlement only if its concentration in aluminum is more than critical one (~3⋅〖10〗^(-4) at T=293 K).

Study on Interface Structure of Cu/Al Clad Plates by Roll Casting

Large scale Atomic/Molecular dynamic Parallel Simulator (LAMMPS) molecular dynamics simulation software was used to simulate the copper and aluminum atom diffusion and changes of interface during heating and cooling process of copper and aluminum composite panels. The structures of the interface were characterized through scanning electron microscope (SEM), X-ray diffraction (XRD), and transmission electron microscope (TEM), and the mechanical properties were also tested. The simulation results show that the diffusion rate of copper atom is higher than that of aluminum atom, and that the CuAl2 radial distribution function of the interface at 300 K is consistent with that of pure CuAl2 at room temperature. At 930 K, t = 50 ps Cu atoms spread at a distance of approximately four Al lattice constants around the Al layer, and Al atoms spread to about half a lattice constant distance to the Cu layer. The experimental results show that the thickness of the interface in copper–aluminum composite plate is about 1 μm, and only one kind of CuAl2 with tetragonal phase structure is generated in the interface, which corresponds with the result of molecular dynamics simulation.

Theoretical design of stable hydride clusters: isoelectronic transformation in the EnAl4−nH7+n− series

Design of stable hydrogen-rich metallic hydrides through substitutions of one aluminum atom by one E–H unit in the Al4H7− cluster (E = Be, Mg, Ca, Sr and Ba atoms).

Reaction of an Al/P-based frustrated Lewis pair with benzophenone: formation of adducts and aluminium alcoholates via β-hydride elimination

Treatment of the Al/P-based frustrated Lewis pair (FLP) Mes2P–C(AltBu2)=C(H)-Ph (1) with benzophenone afforded the simple 1:1 adduct (4) with a O=CPh2 molecule coordinated to the aluminum atom by an Al←O donor-acceptor bond. Steric repulsion may prevent an interaction between the electrophilic carbonyl carbon atom and the Lewis-basic phosphorus atom. 4 is unstable in solution at room temperature, the coordination to aluminium increases the polarisation of the carbonyl group and favours its reduction. As suggested by quantum chemical calculations, a C–H bond of a tBu group approaches the electrophilic center and facilitates β-hydride elimination with the release of isobutene and the formation of an Al–OCHPh2 ligation. An intact O=CPh2 molecule completes the coordination sphere of the metal atom (5). The second tBu group at aluminium reacts similarly by the selective formation of an Al(OCHPh2)2 moiety (6). The thermodynamics of adduct formation and the mechanism of the hydride shift have been evaluated by quantum chemical DFT calculations.