AlCl3 Complexes Research Articles

An Expanded EDA Complex Profile: Construction of Aza-arenes and Their Synthetic Application as Fluorescence Probes.

We developed a visible-light-driven expanded EDA complex profile for the synthesis of aza-arenes via aza-6π electrocyclization of 2-styrylanilines with aromatic aldehydes. This protocol relies on the EDA complexes of AlCl3 with imine to induce the absorption red-shift to visible light from ultraviolet light. An array of 2,3-disubstituted quinolines were constructed smoothly after excitation with blue-light-emitting diodes at room temperature. In addition, the resultant product, used as a cell permeable lipid droplet-specific probe, shows a low working concentration, a short staining time, and functionality in living and fixed cells.

Penetapan Kadar Fenolik dan Flavonoid Total Ekstrak Etanol Buah Parijoto (Medinilla speciosa Blume) dengan Metode Spektrofotometri UV-Vis

Parijoto (Medinilla speciosa) has a wide range of pharmacological activities due to its secondary metabolite content, especially flavonoid, and phenolic compounds. Flavonoid and phenolic compounds have a major role in human health with their activities as antioxidants, anti-inflammatories, antimicrobials, etc. This study aimed to determine the total levels of phenolic and flavonoid compounds from the ethanol extract of Parijoto fruit. Parijoto fruit is obtained from Bandungan, Semarang Regency, Central Java. Extraction was carried out by maceration method with 70% ethanol solvent then concentrated using a rotary evaporator. The total phenolic and flavonoid content amount was determined using the colorimetric method with Folin-ciocalteau complex reagent on phenolic with gallic acid as the reference standard and AlCl3 complex reagent on flavonoids with quercetin as the reference standard. Absorbance was measured using a UV-Vis spectrophotometer. The results showed that the color of the viscous extract of Parijoto fruit was dark brown with a yield of 6.67% w/w. The total phenolic content of the ethanol extract of Parijoto fruit was 21.67 µgGAE/g extract and the total flavonoid content was 9.21 µg QE/g extract.

Determination of Total Phenolic, Total Flavonoid and Antioxidant Activity of Karamunting Leaves (Rhodomyrtus tomentosa (Aiton) Hassk) Extract and Fraction

Karamunting (Rhodomyrtus tomentosa (Aiton) Hassk) is a family of Myrtaceae which has been used by the community as traditional medicine. The purpose of this research is determine total phenolic and total flavonoid level and test antioxidant activity of Karamunting Leaves. Determination of total phenolic using gallic acid standard by the Folin Ciocalteu method. The results obtained total phenolic in water fraction of 99 mgGAE/g, ethanol extract 94,1 mgGAE/g, ethyl acetate fraction 83,3 mgGAE/g and n-hexane fraction 41,4 mgGAE/g. Determination of total flavonoid using standard quersetin with AlCL3 complex formation method, the results obtained total flavonoid in water fraction of 156,8 mgQE/g, ethanol extract 192,6 mgQE/g, ethyl acetate fraction 89,4 mgQE/g and n-hexane fraction 31,3 mgQE/g. Determination of antioxidant activity was determined by DPPH radical capture test (1,1-diphenyl-2-picrylhydrazyl), the results obtained in water fraction with IC50 value 15,02 µg/mL, ethanol extract 14,06 µg/mL, ethyl acetate fraction 14,48 µg/mL with very strong activity of antioxidant, whereas in the n-hexane fraction was categorized as weak antioxidant activity with an IC50 value of 264,02 µg/mL.

An expedient one-pot synthesis of benzophenone Schiff bases from benzene

A simple and efficient one-pot synthesis of benzophenone Schiff bases from benzene, CCl4 and aromatic amines was developed based on the the reaction of benzene with CCl4·AlCl3 complex. This method affords Ph2CCl2 as well as the products of its subsequent reaction with aromatic amines, benzophenone Schiff bases, selectively and in good yields.

Preparation of glycerol plasticized chitosan films using AlCl3·6H2O as the solvent: optical, crystalline, mechanical and barrier properties

Chitosan films plasticized with the complex of AlCl3·6H2O and glycerol were prepared by using AlCl3·6H2O as the solvent. The effect of AlCl3·6H2O and glycerol complex with Chitosan was studied by SEM, XRD, TGA, and tensile testing. The complex would increase the water resistance and destroy the crystals of chitosan film. The TGA results proved that the chitosan film plasticized with the complex showed higher thermal stability at the temperature below 200 °C than pure chitosan film. With the addition of the complex of AlCl3·6H2O and glycerol, the tensile strength of chitosan film decreased and the elongation at break increased.

APPROACH TO STEVIA STANDARDIZATION AS PERSPECTIVE MEDICINAL PLANT: EVALUATION OF STEVIA LEAVES FLAVONOID CONTENTS

Stevia rebaudiana bertolli traditionally used as a sweetener has many pharmacological activities. The objects of the study were stevia leaves grown in the several districts of Russia. Together with sweet glycosides flavonoids can be a marker of stevia quality. Flavonoids from dry stevia leaves were extracted with ethanol-water solutions. The results show that the flavonoid content higher in 40 and 70% ethanol extracts. UV properties of stevia extracts were investigated. Absorption maxima at 300 and shoulder at 290 nm in stevia extracts are revealed. Chemical structures of stevia flavonoids are discussed. After adding aluminum chloride batochromic shifts in the spectra are observed. Complex of stevia flavonoids and AlCl3 had the maximum absorption at 403 nm. Aluminum chloride colorimetric assay were developed to evaluate total flavonoid contains in stevia extracts from the different Russian regions. Total flavonoid contents vary from 2 to 3 %. Maximum flavonoid content found in stevia leaves from the south of Russia.

Mechanism of Glucose Conversion into 5-Ethoxymethylfurfural in Ethanol with Hydrogen Sulfate Ionic Liquid Additives and a Lewis Acid Catalyst

Hydrogen sulfate ionic liquid additives with aluminum chloride catalyst in ethanol were found to promote efficient (30 min) one-pot, one-step transformation of glucose into 5-ethoxymethylfurfural (5-EMF) in 37% yields. Spectroscopic measurements (FT-IR, 1H NMR) showed that ionic liquids form multiple hydrogen bonds with glucose and promote its ring opening through ionic liquid–AlCl3 complexes to enable formation of 5-EMF via 5-hydroxymethylfurfural (5-HMF). Reactions performed in dimethyl sulfoxide using (protic, aprotic) ionic liquid additives with and without AlCl3 catalyst showed that both the ionic liquid and AlCl3 were required for efficient transformation of glucose into 5-EMF. The proposed reaction mechanism for 5-EMF synthesis in the ethanol–1-butyl-3-methylimidazolium hydrogen sulfate–AlCl3 reaction system consists of ring opening of glucose to form the 1,2-enediol and dehydration to form 5-HMF that is followed by etherification to the 5-EMF product. The reaction system is effective for glucose t...

Assessment of phenolic profile and antioxidant power of five pistachio (Pistacia vera) cultivars collected from four geographical regions of Iran.

In this study, the levels and antioxidant activities of some secondary metabolites isolated from five pistachio (Pistacia vera) cultivars collected from four different geographical regions of Iran, were studied. Total phenolic compounds levels were determined by Folin-Ciocalteu method. Total flavonoid content was determined as AlCl3 complex and expressed as mg of quercetin equivalents (QE)/g dry extract and total proantocyanidins content was expressed as mg of catechin equivalents (CA)/g dry extract. In order to evaluated the antioxidant activity of the compounds, DPPH and FRAP assays were used. The highest level of total phenols (156.42 mg GA/g DE), total flavonoids (130.94 mg QE/g DE) and total proantocyanidins (152.816 mg CA/g DE) were obtained in Akbari cultivar from Rafsanjan, followed by Badami-e-sefid and Ahmad aghaei. The lowest amount of total phenolic content (TPC), total flavonoid content (TFC) and total proanthocyanidin content (TPrAC) were found in Badami-e-sefid from Feizabad (128.140 mg GA/g DE, 93.176 mg QE/g DE and 118.870 mg CA/g DE, respectively). Also, a positive correlation (r2=0.9834) was found between antioxidant activity and total phenolic compounds. Pistachio increased their phytochemical compounds to contrast with abiotic stress. Our data could be useful for introducing special characteristics to the plants, and can be considered when planning a new breeding program or choosing a specific cultivar for a particular use.

Quantitative Characterization of Lewis Acidity and Activity of Chloroaluminate Ionic Liquids

Pyridine can act as a basic indicator for both Bronsted and Lewis acids forming different types of bonds. Infrared spectroscopy, in combination with 27Al NMR spectroscopy, was employed to study the interaction mechanism of pyridine and chloroaluminate ionic liquids (ILs). The acid type, acid amount, acidity, and even activity of chloroaluminate ILs could be determined. An in situ infrared complexometric titration was developed as a quantitative characterization method for determining the different acidities and catalyst activity. The method is based on the principle that Lewis acidic chloroaluminate [Al2Cl7]− anion reacts with pyridine to form the [AlCl4]− anion and pyridine–AlCl3 ([PyAlCl3]) complexes, while the Bronsted acid forms a pyridinium salt. Both product types showed characteristic shifts of the pyridine peaks in the infrared spectrum.

Preparation and properties of plasticized chitosan/starch cast films using AlCl3·6H2O aqueous solution as the solvent

In this paper, the chitosan/starch (CS/ST) cast films were prepared using AlCl3·6H2O aqueous solution as the solvent for CS. AlCl3·6H2O was retained in the CS/ST film acting as the plasticizer and glycerol were added to form the complex plasticizer with AlCl3·6H2O. The effect of the complex plasticizer of AlCl3·6H2O and glycerol on the crystalline, thermal stability, and mechanical properties of CS/ST films was studied by X-ray diffraction, thermal gravity analysis, and tensile testing, respectively. The results showed that AlCl3·6H2O aqueous solution was a better solvent for CS than acetic acid aqueous solution which is the most commonly used solvent of CS. With AlCl3·6H2O aqueous solution as the solvent, the thermal degradation of CS and ST in the dissolving process was weakened. Glycerol could form the synergism plasticizing effect with AlCl3·6H2O. With the complex of AlCl3·6H2O and glycerol as the plasticizer, the CS/ST film with the good mechanical properties could be obtained.

Preparation of Poly(ether ketone)s Derived from 2,5-Furandicarboxylic Acid by Polymerization in Ionic Liquid

Aromatic poly(ether ketone)s were synthesized by the Friedel–Crafts polymerization of 2,5-furandicarbonyl dichloride prepared from biomass and petroleum-based aromatic ethers such as diphenyl ether and 1,4-diphenoxybenzene with aluminum chloride (AlCl3). The polymerizations in common molecular solvents such as 1,2-dichloroethane and nitrobenzene did not afford polymers. The Friedel–Crafts polymerization usually undergoes in the swollen gel of the oligomer–AlCl3 complexes; the precipitated physical gels had not been enough swollen. The polymerizations were carried out in various ionic liquids to form swollen gels. The polymerizations proceeded in specific ionic liquid such as 1-butyl-3-methylimidazolium chloride ([C4mim]Cl), and high molecular weight polymers were obtained with good yield. The gels formed in [C4mim]Cl were more highly swollen, and additionally the rate constant estimated by the model reaction of 2,5-furandicarbonyl dichloride and anisole was higher in [C4mim]Cl than that in 1,2-dichloroethane. The obtained poly(ether ketone)s exhibited good thermal stability and chemical resistance comparable to common poly(ether ketone)s.

Electrochemical Studies of 9,10-Anthraquinone in Adiponitrile

The electrochemical reduction of 9,10-anthraquinone (AQ) has been found to occur in two reversible one-electron processes in the adiponitrile (ADN)/0.20 M TEA BF4 solvent system. Upon addition of aluminum(III) trifluoromethanesulfonate to the solution, the initial reduction process is shifted to a more positive potential due to complexation of the carbonyl oxygen by Al3+. As AQ is reduced, the Al3+ is also able to react with the AQ reduction products. Even at the 0.40 Al3+:1.00 AQ point, the initial reversible processes are entirely absent, implying that Al3+ is able to interact with, or complex, approximately three 9,10-anthraquinone dianion reduction products. This high degree of interaction is also reflected in the large 1.0 V separation between the potentials for reduction of the AQ(AlCl3) complex and the oxidation of the complexed AQ dianions.

Structure and stability of molecular and ionic complexes of AlCl3 with pyrazine and 4,4′-bipyridyl

Structural and thermodynamic characteristics of molecular and ionic complexes of aluminum trichloride with pyrazine (pyz) and 4,4′-bipyridyl (bipy) are calculated at the RI-BP86/def2-SVP level. It is found that for molecular 2AlCl3·3L and 4AlCl3·3L complexes an energy difference between isomers does not exceed 4 kJ/mol, and the rotation barrier of the AlCl3 moiety relative to the N-Al-N bond does not exceed 24 kJ/mol. A comparison of the stability of molecular and ionic complexes of aluminum in the gas phase shows that the maximum energy difference is ∼60 kJ/mol. For L = pyz the molecular complex is more stable whereas for L = bipy it is the ionic one.

Electrochemical Investigation of Quinone Complexation by Lewis Acids in a Chloroaluminate Ionic Liquid

The electrochemical behavior of 9,10-anthraquinone (AQ) has been investigated in the initially neutral aluminum chloride : 1-ethyl-3-methylimidazolium chloride ionic liquid. It has been found that AQ is characterized by a single irreversible redox process in the neutral melt. Additions of AlCl3 cause a positive potential shift, first by the formation of two reversible redox processes corresponding to AlCl3 complexes of AQ under mildly acidic conditions, and then by the appearance of a shifted irreversible redox process in an acidic melt. HfCl4 additions cause similar behavior, except that the reversible systems persist at higher Lewis acid levels than for AlCl3. At the 11:1 Lewis acid: AQ point, AQ is still soluble as an orange solution for AlCl3 additions, but a yellow solid precipitates from a yellow (amber) solution for HfCl4 additions.

Cationic polymerization of isobutylene by AlCl3/ether complexes in non-polar solvents: Effect of ether structure on the selectivity of β-H elimination

The cationic polymerization of isobutylene co-initiated by a number of complexes of AlCl3 with linear (Et2O, Bu2O, Am2O, Hex2O, MeOPh) and branched (iPr2O, tBuOMe) ethers in toluene or CH2Cl2 at −20 °C has been investigated. Among them, the complexes with ethers of moderate basicity (AlCl3 × OBu2 and AlCl3 × OiPr2) afforded polyisobutylenes with the highest exo-olefin terminal groups content (80–95%) and monomer conversion, while the use of such weak ether as anisole led to the conventional polyisobutylenes containing mainly tri- and tetra-substituted olefinic end groups (90–95%). The complexes of AlCl3 with tert-butyl methyl ether or tetrahydrofuran are characterized by low stability at room temperature due to the ether cleavage by such strong Lewis acid as AlCl3. The polymerization of isobutylene in the presence of AlCl3 × OBu2 or AlCl3 × OiPr2 as co-initiators could be successfully performed in n-hexane at elevated temperatures (−20 °C to 10 °C) and at high monomer concentrations (up to [M] = 7.8 M) to afford low molecular weight polyisobutylenes (Mn = 1000–8000 g mol−1) with relatively broad MWD (Mw/Mn = 2–4) containing high amount of exo-olefin terminal groups (exo = 70–85%).

Synthesis of 1,2,3,4‐Tetramethyl‐ and 1,2,3,4‐Tetraethylfluorene through a Dewar Benzene Pathway

AbstractA simple and selective synthesis of 1,2,3,4‐tetra(m)ethylfluorenones and ‐fluorenes was achieved by using Dewar benzenes as important intermediates. The corresponding Dewar benzenes were prepared by reactions of tetraalkylcyclobutadiene–AlCl3 complexes with methyl phenylpropynoate. Their subsequent hydrolysis followed by photochemical rearrangement provided substituted biphenylcarboxylic acids. Treatment of the prepared acids with thionyl chloride gave rise to the fluorenones, which were reduced to the respective fluorenes. A Ru complex with 1,2,3,4‐tetraethylfluorenone was prepared.

A reactivity-selectivity study of the Friedel-Crafts acetylation of 3,3'-dimethylbiphenyl and the oxidation of the acetyl derivatives.

BackgroundFriedel-Crafts acetylation is an important route to aromatic ketones, in research laboratories and in industry. The acetyl derivatives of 3,3′-dimethylbiphenyl (3,3′-dmbp) have applications in the field of liquid crystals and polymers and may be oxidized to the dicarboxylic acids and derivatives that are of interest in cancer treatment.FindingsThe effect of solvent and temperature on the selectivity of monoacetylation of 3,3’-dmbp by the Perrier addition procedure was studied using stoichiometric amounts of reagents. 4-Ac-3,3′-dmbp was formed almost quantitatively in boiling 1,2-dichloroethane and this is almost twice the yield hitherto reported. Using instead a molar ratio of substrate:AcCl:AlCl3 equal to 1:4:4 or 1:6:6 in boiling 1,2-dichloroethane, acetylation afforded 4,4′- and 4,6′-diacetyl-3,3′-dmbp in a total yield close to 100%. The acetyl derivatives were subsequently converted to the carboxylic acids by hypochlorite oxidation. The relative stabilities of the isomeric products and the corresponding σ-complexes were studied by DFT calculations and the data indicated that mono- and diacetylation followed different mechanisms.ConclusionsFriedel-Crafts acetylation of 3,3′-dmbp using the Perrier addition procedure in boiling 1,2-dichloroethane was found to be superior to other recipes. The discrimination against the 6-acetyl derivative during monoacetylation seems to reflect a mechanism including an AcCl:AlCl3 complex or larger agglomerates as the electrophile, whereas the less selective diacetylations of the deactivated 4-Ac-3,3′-dmbp are suggested to include the acetyl cation as the electrophile. The DFT data also showed that complexation of intermediates and products with AlCl3 does not seem to be important in determining the mechanism.

Oligomerization of α-octene catalyzed by zeolites

The oligomerization of octene-1 was studied in the presence of zeolites of different structural types (e.g., Y, Beta, ZSM-12, and ZSM-5). It was shown that at 150–200°C, wide-pore zeolite catalysts Y, Beta, and ZSM-12 exhibit high catalytic activity in the reaction. The conversion of catalyzed octene can be as high as 96%, and the yield of oligomers is 88–100 wt %. Zeolite ZSM-5 at 150–180°C has low activity and mainly catalyzes the isomerization of octene-1. As the temperature rises to 250°C, low molecular weight oligomers resulting from the cracking process are the main products of this reaction. The activity and selectivity of zeolite catalysts in the oligomerization of octene-1 are conditioned by their acidic properties and structural characteristics, as well as by the reaction conditions. It was revealed that the main oligomerization products are octene dimers having an alkylnaphthene structure and containing unsaturated hydrocarbons with tri- and tetra-substituted double bonds in amounts of 2.2–3.2%. The properties of the octene oligomers synthesized in the presence of zeolite Beta are similar to the characteristics of hydrogenated poly-α-olefins, the oligomerization of which was performed on AlCl3 complexes.

Conformational study on the structures and energies of the weakly bound complexes of AlCl3 with diatomic molecules

Article Conformational study on the structures and energies of the weakly bound complexes of AlCl3 with diatomic molecules was published on March 1, 2008 in the journal Open Chemistry (volume 6, issue 1).

Conformational study on the structures and energies of the weakly bound complexes of AlCl3 with diatomic molecules

AbstractIn this work we present the results of high level ab initio calculations on weakly bound complexes of aluminium trichloride and hydrogen halides, HX, halogens, X2 and diatomic interhalogens, XY (where X, Y = F, Cl, Br). Based upon these calculations we have predicted that all structures in the staggered conformation (except for Cl3AlFH and Cl3AlClH) are stable minima while those in the eclipsed configurations are transition state structures. In the XH complexes the strength of interaction with the Cl3Al group is FH > ClH > BrH. In the case of X2 species it is Br2 > F2 > Cl2, and finally in the XY (YX) group it is: FBr > ClBr > FCl > BrCl > BrF > ClF.