Long-chain Amines Research Articles

ChemInform Abstract: Mesoporous Silica MCM‐41 as a Highly Active, Recoverable and Reusable Catalyst for Direct Amidation of Fatty Acids and Long‐Chain Amines.

Direct amidation of fatty acids with long-chain amines was successfully performed by mesoporous silica MCM-41, which showed the highest catalytic activity among other used homo- and heterogeneous catalysts. It was found that MCM-41 can be easily recovered from the reaction mixture followed by simple calcination treatment and reused without loss of its catalytic activity.

Separation of Picric Acid with Trioctyl Amine (TOA) Extractant in Diluents

Separation of 2,4,6-trinitrophenol (Picric acid) from aqueous solution by trioctyl amine (TOA), which is a long-chain aliphatic amine, has been studied at 298 K. Diluents (alcohols) (isoamyl alcohol, octan-1-ol, decan-1-ol) have been used to dissolve TOA. Experimental results of batch extraction are calculated and reported as distribution coefficients (KD), loading factors (Z), and extraction efficiency (E). The most effective diluent has been found to be isoamyl alcohol with a distribution coefficient value of 19.333. In this article, the linear solvation energy relationship (LSER) modeling (included Hidebrand-Hansen solubility parameters) has been done on the reactive extraction of picric acid to obtain the model parameters. Modeling using an LSER model predict a close resemblance of experimental data.

Mesoporous silica MCM-41 as a highly active, recoverable and reusable catalyst for direct amidation of fatty acids and long-chain amines

Direct amidation of fatty acids with long-chain amines was successfully performed by mesoporous silica MCM-41, which showed the highest catalytic activity among other used homo- and heterogeneous catalysts. It was found that MCM-41 can be easily recovered from the reaction mixture followed by simple calcination treatment and reused without loss of its catalytic activity.

ChemInform Abstract: Conversion of Long-Chain Terminal Alcohols and Secondary Amines into Tertiary Amines Using Ruthenium(II) Tertiary Phosphine Complexes as Homogeneous Catalysts.

ChemInform Abstract: Conversion of Long-Chain Terminal Alcohols and Secondary Amines into Tertiary Amines Using Ruthenium(II) Tertiary Phosphine Complexes as Homogeneous Catalysts.

The Effect of Sulphuric Acid Concentration on Solvent Extraction of ReO4 - by the Long-Chain Aliphatic Tertiary Amines and Alcohols

The effect of sulphuric acid concentration on solvent extraction of ReO4- by the long-chain aliphatic tertiary amines and alcohols in a wide range of H2SO4 concentrations in initial solutions is discussed. It has been established that the influence of the sulphuric acid concentration on rhenium solvent extraction is largely due to the extraction process mechanism. In the case of the anion-exchange mechanism, ReO4- is best extracted from weakly acidic solutions, whereas when the hydrate-solvate mechanism takes place – from solutions containing 4-7 mole/l H2SO4.

Solid-State 51V NMR Investigation of the Intercalation of Alkylamines into Layered α-Vanadyl Phosphate

The intercalation behavior of layered alpha-phase vanadyl phosphate, alpha-VOPO(4).2H(2)O (alpha-VP), with alkylamine was investigated by (51)V solid-state NMR in combination with powder XRD. The XRD results show that the amines form bimolecular layers upon intercalation. For the intercalation with short chain amines (propylamine, pentylamine, and hexylamine), the C-C chain of the amines is tilted with respect to the inorganic basal plane. The amines with a longer alkyl chain (dodecylamine and hexadecylamine) tend to adopt an orientation where the C-C chain direction is perpendicular to the VP layer. For the amine with eight carbon atoms (octylamine), the intercalation results in two coexisting phases with different chain orientations. (51)V solid-state NMR was used to directly probe the effect of intercalation on the metal center environments. Both (51)V magic-angle spinning and static spectra of alpha-VP intercalated with different amines were obtained at different magnetic fields, and they are sensitive to intercalation. The intercalation induces the (51)V isotropic chemical shift to move toward deshielded direction. (51)V chemical shielding parameters such as the span are sensitive to the orientation of the amine chain with respect to the VP basal plane. For the V centers interacting with the amines having a tilted orientation, the (51)V span gradually decreases with increasing alkyl chain length. However, the span of the (51)V atoms interacting with the amines perpendicular to the VP layer is larger and independent of the length of the alkyl chain. The (51)V NMR data indicate that for the alpha-VPs intercalated with long-chain amines, such as dodecylamine and hexadecylamine, the amines can assume both tilted and perpendicular orientations.

Magnetic Cu–Ni (core–shell) nanoparticles in a one-pot reaction under microwave irradiation

We successfully prepared face-centered cubic (fcc) Cu-Ni (core-shell) nanoparticles by intramolecular reduction of formate complexes of Cu(2+) and Ni(2+) with long-chain amine ligands in a one-pot reaction within an extremely short time realized only under microwave irradiation. Observation by an HAADF-STEM technique showed that the nanostructure in one particle consisted of a Ni-rich shell and a Cu-rich core. Cu(4)Ni(6) nanoparticles with an average size of 11.7 nm were comprised of a Cu core with a diameter of ca. 6.0 nm, a Ni shell ca. 1.6 nm thick and a 0.9 nm thick interlayer of mixed Cu-Ni alloy between the Cu core and the Ni shell. Both the oxidation characteristics and the magnetic properties were dramatically affected by the molar ratios of Cu : Ni in the Cu-Ni nanoparticles. The magnetization of Cu(3)Ni(7) and Cu(4)Ni(6) comprised of a diamagnetic Cu-rich core, ferromagnetic Ni-rich shell and antiferromagnetic NiO-rich layer on the particle surface showed an exchange bias (209 and 143 Oe, respectively).

Reversible phase transfer and fractionation of Au nanoparticles by pH change

The reversible transfer of Au nanoparticles between water and chloroform phases by pH change was achieved by using a long-chain amine derivative. Further, we demonstrated that the phase transfer method was very effective for the fractionation of Au nanoparticles according to their crystal facet distinction.

Calcium-Incorporated Mesoporous Aluminosilicates: Synthesis, Characterization, and Applications to the Condensation of Long-Chain Fatty Acid with Long-Chain Amine and Alcohol

A comprehensive study on a series of highly stable calcium containing mesoporous aluminosilicate molecular sieves (CaAlMMSH) having different acidic properties has been made by varying the Si/Ca ratio in synthesis gels. The structural, physical, and porous properties of these microporous/mesoporous composite materials were characterized by X-ray diffraction, N2 adsorption/desorption isotherm measurements, solid-state 27Al and 29Si magic angle spinning NMR, and variable-temperature hyperpolarized 129Xe NMR, Fourier transform infrared (FTIR) and diffuse reflectance FTIR spectroscopies. As compared to the parent AlMMSH materials, the incorporation of excessive amount of calcium tends to result in an overall increase in acid amount while at the expense of strong acid sites. The CaAlMMSH materials were found to have superior catalytic activities than AlMMSH in the amidation of palmitic acid with N-hexadecylamine. However, no significant enhancement in catalytic activity for the esterification of palmitic acid ...

Au Growth on Semiconductor Nanorods: Photoinduced versus Thermal Growth Mechanisms

Gold growth on CdS nanorods and on seeded CdSe/CdS nanorods with and without illumination at different temperatures was studied. Two competing mechanisms were identified: thermal and light-induced growth. The thermal mechanism leads to growth of small gold particles at defects along the rod body and can be suppressed at lower temperatures. This control is attributed to a phase transition of the alkyl chains of the surface amine ligands to a static phase at lower temperatures, blocking the Au precursor's access to the nanorod surfaces. While a long-chain (C18) amine shows effective blocking at 293 K, a shorter chain (C12) amine shows the same result only at 273 K; however, in the case of a bulky trialkylamine, defect growth was observed even at 273 K. Light-induced growth leads to selective deposition of gold on one end of the rods. The tip was shown to grow on sulfur-rich facets of the nanorod, producing end-on and angled tip orientations. Growth under illumination with decreased temperature provides a highly selective synthesis of hybrid semiconductor nanorods with a single gold tip. Such anisotropic semiconductor-metal hybrids are of interest for self-assembly and photocatalysis and as building blocks in optoelectronic devices.

Microwave-Assisted Synthesis of Monodisperse Nickel Nanoparticles Using a Complex of Nickel Formate with Long-Chain Amine Ligands

Abstract We have successfully prepared face-centered cubic (fcc) Ni nanoparticles by the intramolecular reduction of Ni2+ ion contained in a formate complex having long-chain amine ligands within an extremely short time under microwave irradiation. Formate ion coordinated to Ni2+ ion acted as a reducing agent for Ni2+ in this reaction and finally decomposed to hydrogen and carbon dioxide. Ligation of the long-chain amine lowered the reaction temperatures by decreasing the energy barrier required for the reduction of the nickel formate complex. Monodisperse Ni nanoparticles with average sizes of 43, 71, and 106 nm were prepared using the complex of nickel formate with several chain lengths of alkylamines such as oleylamine (=(Z)-9-octadecenylamine), myristylamine (=tetradecylamine), and laurylamine (=dodecylamine), respectively. The relationship between the magnetic properties and the particle sizes of Ni nanoparticles is discussed.

Precipitation of dodecyl amine in KCl–NaCl saturated brine and attachment of amine particles to KCl and NaCl surfaces

Long-chain amines, used in potash ore flotation as collectors, are insoluble in NaCl–KCl saturated brine. In commercial applications, these amines are melted at 70–90 °C, dispersed in acidic solution of hydrochloric or acetic acids, and such emulsions are then introduced to the flotation pulp. To model the commercial potash ore flotation process, dodecyl amine, used in this study, was melted at 70 °C, dispersed in hydrochloric acid aqueous solution and was added to a KCl–NaCl saturated brine at room temperature. This results in the precipitation of the amine. The present study summarizes the influence of the conditions on the particle size and morphology of the precipitating amine particles. Methyl isobutyl carbinol (MIBC), common frother in flotation processes, was shown to affect amine dispersion when added into a hot amine emulsion prior to mixing with a saturated brine. This study demonstrates that the precipitating amine particles are selectively abstracted by KCl particles, but not by NaCl particles.

Titanium dioxide/amine hybrid nanotubes. Optical properties and behavior as lithium–ion electrode

Titanium dioxide based tubular nanocomposites containing long-chain amines were prepared by hydrothermal reaction of anatase with neutral surfactants, dodecylamine and octadecylamine, under strong alkaline conditions. Morphologically pure phases are obtained after reaction times of about 50 h at 130 °C. Dodecylamine derivates are structural and thermally more fragile than those with octadecylamine. Under more drastic reaction conditions, 72 h at 150 °C, amine is segregated leading to almost pure inorganic nanotubes or fibers for octadecyl and dodecyl derivatives respectively. The products characterized by electron microscopy, X-ray diffraction, FT-IR and elemental analysis are constituted by the hydrogen titanat H 2Ti 3O 7. Diffuse reflectance spectra reveal the products present typical size-dependent optical properties. The photoluminescence spectra are qualitatively similar to that of anatase dominated by the presence of traps located in the band gap. The electrochemical lithium intercalation and lithium diffusion coefficients of the products were studied by intermittent galvanostatic method and galvanostatic pulse relaxation technique respectively. Products were tested in a lithium cell using the nanocomposites as the active material of the positive electrode. The hybrid dodecylamine derivative shows a first cycle irreversible capacity of 219 mAh/g, and a capacity of 113 mAh/g after the 7th cycle which results improved in comparison with those reported for H 2Ti 3O 7 electrodes, thus pointing to a protective effect of the amine.

Controlling the crystal structure of Ni nanoparticles by the use of alkylamines

Ni nanoparticles were prepared via thermal decomposition of nickel acetate tetrahydrate in the presence of long-chain amines, which acted as both solvents and reducing agents. By tuning the reaction temperature, Ni nanostructures with either hcp or fcc crystal structure were obtained. In principle, higher temperatures favored the formation of hcp nanoparticles. The employment of additional surfactants such as 1-adamantanecarboxylic acid and trioctylphosphine-oxide facilitated the tuning of the particles’ growth limit. The size of the particles varied between 5 and 120 nm. The magnetic features of fcc-Ni nanoparticles were quite similar to the corresponding ‘bulk’ ones. On the other hand, the hcp-Ni particles showed weak magnetic features, reflected by low magnetization values, the absence of saturation magnetization and by blocking temperatures far below room temperature.

Aqueous solutions of geminal alkylammonium surfactants as a medium for reactions of long-chain amines

The formation of surfactant-hydrophobic amine mixed aggregates reduces the pK a of long-chain amines by 1–1.5 units compared with those in molecular solutions and is an important factor responsible for the high catalytic effect of the system in ester bond cleavage. In aqueous solution of geminal surfactants, the rate of azomethine formation in the reaction of long-chain amines with benzaldehydes is an order-of-magnitude higher than in ethanol.

Synthesis of folate-conjugated amphiphiles for tumor-targeted drug delivery

Folic acid was derivatized specifically at its γ-carboxyl group to retain its ligand-binding activity to the folate receptor α (FRα) present on HeLa cells. Amphiphilic molecules labeled with folic acid were prepared by conjugation of long-chain primary amines directly or via diamine linkers to the γ-carboxyl group of folic acid. Folic acid amphiphiles labeled with fluorescent 7-amino-4-carbamoylmethylcoumarin (ACC) were also prepared to visualize the uptake of amphiphiles in folate receptor positive cells. The structures of the new compounds were verified by proton NMR and MALDI-TOF mass spectrometry. The amphiphiles form micelles in water. Critical micelle concentrations (CMCs) were determined by the pyrene fluorescence method for folic acid amphiphiles and the rise in capillary height method for the fluorescently labeled amphiphile. The CMCs of the amphiphiles were studied in buffer solution at pH 8 and ranged from 2 to 64 μM. The formation of micelle increased the solubility of paclitaxel, a model lipophilic anticancer compound, by more than 80%. A significant amount of the fluorescently tagged amphiphile was internalized into HeLa cells known to express FRsα when compared with Caco-2 cells that do not express FRα. Therefore, folate-labeled amphiphiles show promise in targeting antitumor agents to FRα-expressing cancer cells.

Adsorption of long-chain aliphatic amines—components of corrosion inhibitors

Adsorption of certain long-chain aliphatic amines with 6–18 carbon atoms is studied on a stationary mercury drop electrode using the impedance method. It is found that adsorption of amines with C6–C12 results in the formation of an adsorption layer with the limiting capacitance of about 5 μF/cm2. In the case of amines with C14–C16, the limiting capacitance is approximately 0.5–0.7 μF/cm2. The most probable reason for such abrupt decrease in the adsorption layer capacitance is the formation of condensed layers of adsorbate molecules at the electrode surface. The adsorption parameters are calculated for hexylamine. The surface activity is estimated for amines with 10–14 carbon atoms in their chains.

Effective Intercalation and Exfoliation of Nanoplatelets in Epoxy via Creation of Porous Pathways

A new surface modification approach for improving intercalation and exfoliation efficiency of layered nanoplatelets is introduced on the basis of α-zirconium phosphate (α-ZrP) nanoplatelets. The intercalation of α-ZrP nanoplatelets was carried out using a number of different organic surface modifiers and their combinations. It is found that porous pathways, which can be created by incorporating a combination of a linear long-chain amine and a bulky, short-chain amine as intercalating agents, can lead to speedier and more effective intercalation. Consequently, fully exfoliated polymer nanocomposites can be more easily prepared. The intercalation/exfoliation mechanisms accounting for the observed effectiveness are discussed.

Inorganic Fullerenes: From Lamellar Precursors to Functionalized Nanotubes

The intercalation of long-chain primary amines into the laminar matrices of MoS 2 or V 2 O 5 -gel leads to well ordered, lamellar organic-inorganic nanocomposites. Powder X-ray diffraction analysis, stoichiometry determined by chemical analysis, and considerations on the molecular volume of the guest and surface available indicate the guest is oriented in the interlaminar space with their molecular axis perpendicular to the matrix plane. The hydrothermal treatment of these products leads to the formation of multiwall nonotubes with the organic component intercalated between inorganic layers. The composition and the shape of the tubes indicate that the tube formation should occur by the rolling up of precursor laminae.

Synthesis and characterization of Al- and Ti-MCM-41 materials: application to oxidation of anthracene

The synthesis and characterization of new molecular sieves of the MCM-41 type are presented in this study. Samples were obtained from the alkoxides of Si, Ti and Al and different long-chain amine and alkylammonium salts surfactants, by the sol-gel method, through moderate agitation at room temperature. The reactions were conducted in two steps, acid hydrolysis (pH=2) and alkaline condensation (pH=10), both taking about 90min. The synthesized crystals were characterized using infrared spectroscopy, thermogravimetry and X-Ray diffraction. Pore diameters and surface areas were measured by N2 adsorption at 77K. Catalytic tests were conducted for anthracene oxidation using different oxidants (H2O2, alkylhydroperoxide) and organic solvents (benzene, tetrahydrofuran).