Presence Of Titanium Tetrachloride Research Articles

THE INFLUENCE OF THE CONCENTRATION OF CHLORINE-CONTAINING CONDENSING AGENTS IN THE SYNTHESIS OF CARBOXYLIC ACID ANILIDESТ

Chlorine-containing condensing agents (PCl3, TiCl4, SiCl4) are widely used in the synthesis of carboxylic acid arylamides by the reaction of arylamines with carboxylic acids in stoichiometric amounts, and often in excess (40–150 mol % relative to the latter). To find the optimal amount of the condensing agent used, the acylation of aniline with 3-hydroxy-2-naphthoic acid in boiling ortho-xylene was studied in the PCl3 concentration range of 0–10 mol % from 3-hydroxy-2-naphthoic acid. It has been established that phosphorus tri-chlorochloride plays the role of a condensing agent and a catalyst, while 3-hydroxy-2-naphthoic acid anilide is formed along two routes with different rates, which can be separated kinetically. The first route includes the rapid synthesis of acid chloride, its interaction with aniline to obtain the target product. The second route is implemented due to phosphorous acid, which is formed from phosphorus trichloride and is a true acylation catalyst.
 The maximum yield of anilide 3-hydroxy-2-naphthoic acid decreases with increasing catalyst concentration, approximately propor-tional to the amount of aniline phosphite formed from it in the mass, which, apparently, is not reactive when interacting with the starting acid.
 Similar patterns were also found in the acylation of aniline with benzoic and salicylic acids in the presence of phosphorus trichloride; benzoic acid in the presence of titanium tetrachloride; 3-hydroxy-2-naphthoic acid in the presence of silicon tetrachloride. They allow a new look at the role of these products (PCl3, TiCl4, SiCl4) as condensing agents and/or ca­talysts in the synthesis of amides of carboxylic acids.
 Taking into account the obtained results, in practice it is better to use PCl3 as a catalyst in an amount not exceeding 2–2.5%, or even to replace it with phosphorous acid. This allows to completely get rid of the release of hydrogen chloride, significantly reduce the consumption rates for raw materials, simplify the entire technological process, reduce the amount of waste, ensure the yield of 3-hydroxy-2-naphthoic acid anilide close to quantitative, create a direct catalytic amidation technology that fully meets the criteria «green» chemistry processes.

Palladium-Catalyzed Intramolecular Allylic Amidation via Decarboxylative Aromatization: Synthesis of N-Allyl-N-aryl Sulfonamides.

A protocol in the preparation of functionalized N-allyl-N-aryl sulfonamides via palladium-catalyzed intramolecular decarboxylative N-allylation reaction is presented. The alkylated 2,5-cyclohexadienyl ketoesters reacted with arylsulfonamides in the presence of titanium tetrachloride and pyridine, which allows the formation of alkylated 2,5-cyclohexadienyl sulfonyl iminoesters which then undergo a palladium-catalyzed intramolecular allylic amidation through decarboxylative aromatization to provide functionalized N-allyl-N-aryl sulfonamides. This allylation protocol proceeds with good regioselectivity. Moreover, we have also shown that N-allyl-N-aryl sulfonamide can be transformed into 4-aryl-1,2,3,4-tetrahydroquinoline and nitrogen-containing β-hydroxysulfide bioactives.

Persistent Solid‐State Phosphorescence and Delayed Fluorescence at Room Temperature by a Twisted Hydrocarbon

AbstractThe dehydrating cyclotrimerization of 1‐tetralone in the presence of titanium tetrachloride at high temperatures leads to homotruxene, a nonplanar arene in which the twist angles between its three outer benzene rings and the central benzene are stabilized by ethylene bridges. This non‐planar configuration allows for pronounced spin–orbit coupling and a high triplet energy, leading to room‐temperature phosphorescence in air with a lifetime of 0.38 s and a quantum yield of 5.6 %, clearly visible to the human eye after switching off the excitation. Triplet–triplet annihilation is found to simultaneously lead to a substantial delayed fluorescence, unprecedented from a pure hydrocarbon at ambient conditions, with a lifetime of 0.11 s.

Persistent Solid‐State Phosphorescence and Delayed Fluorescence at Room Temperature by a Twisted Hydrocarbon

The dehydrating cyclotrimerization of 1-tetralone in the presence of titanium tetrachloride at high temperatures leads to homotruxene, a nonplanar arene in which the twist angles between its three outer benzene rings and the central benzene are stabilized by ethylene bridges. This non-planar configuration allows for pronounced spin-orbit coupling and a high triplet energy, leading to room-temperature phosphorescence in air with a lifetime of 0.38 s and a quantum yield of 5.6 %, clearly visible to the human eye after switching off the excitation. Triplet-triplet annihilation is found to simultaneously lead to a substantial delayed fluorescence, unprecedented from a pure hydrocarbon at ambient conditions, with a lifetime of 0.11 s.

In-situ development of highly photocatalytic multifunctional nanocomposites by ultrasonic acoustic method

Cotton-titania nanocomposites with multifunctional properties were synthesized through ultrasonic acoustic method (UAM). Ultrasonic irradiations were used as a potential tool to develop cotton-titania (CT) nanocomposites at low temperature in the presence of titanium tetrachloride and isopropanol. The synthesized samples were characterized by XRD, SEM, EDX and ICP-OES methods. Functional properties i.e. Ultraviolet protection factor (UPF), self-cleaning, washing durability, antimicrobial and tensile strength of the CT nanocomposites were evaluated by different methods. Central composite design and response surface methodology were employed to evaluate the effects of selected variables on responses. The results confirm the simultaneous formation and incorporation of anatase TiO2 with average crystallite size of 4nm on cotton fabric with excellent photocatalytic properties. The sustained self-cleaning efficiency of CT nanocomposites even after 30 home launderings indicates their excellent washing durability. Significant effects were obtained during statistical analysis for selected variables on the formation and incorporation of TiO2 nanoparticles (NPs) on cotton and photocatalytic properties of the CT nanocomposites.

Synthesis of some novel quinone diimine derivatives of benzo‐15‐crown‐5 for application in Hg2+ recognition

A series of novel fluoroionophore bearing derivatives of benzo-15-crown-5 were synthesized by the amination of benzo-15-crown-5 followed by condensation with different quinones in the presence of titanium tetrachloride (TiCl4 ) and 1,4-diazabicyclo-[2.2.2]octane. The compounds were characterized by infrared, (1) H and (13) C nuclear magnetic resonance, mass spectroscopy and elemental analysis. Absorption and fluorescence spectral characteristics of these compounds were studied. It was observed that the anthraquinone derivative was acting as an Hg(2+) ion sensor.

Synthesis of a Series of Diphenyl (Arylamino)(Pyridin-3-yl)Methylphosphonates as Potential Antimicrobial Agents

Diphenyl 1-(arylamino)(pyridin-3-yl)methylphosphonates were obtained in high yields from the reactions of nicotinaldehyde with aromatic amines and triphenylphosphite in the presence of titanium tetrachloride (TiCl4) as a catalyst. The structures of the synthesized compounds were confirmed by IR, 1H NMR and mass spectral data and their purities were confirmed by elemental analyses. The synthesized α-aminophosphonates showed moderate to high antimicrobial activities against Escherichia coli (NCIM2065) as a Gram-negative bacterium, Bacillus subtilis (PC1219) and Staphylococcus aureus (ATCC25292) as Gram-positive bacteria, and Candida albicans and Schccaromycies cerevisiae as fungi, at various concentrations (10–100 μg/mL).The lethal dose of the synthesized compounds was also determined and indicated that most compounds are safe to use. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the related elements to view the free supplemental file.

Pyrrolopyrrole aza-BODIPY analogues: a facile synthesis and intense fluorescence

Pyrrolopyrrole aza-BODIPY analogues were synthesized from diketopyrrolopyrrole and heteroaromatic amines in the presence of titanium tetrachloride. These novel compounds exhibit intense absorption in the visible region and strong emission with high fluorescence quantum yields greater than 0.8.

ChemInform Abstract: Titanium‐Mediated Direct Carbon—Carbon Double Bond Formation to α‐Trifluoromethyl Acids: A New Contribution to the Knoevenagel Reaction and a High‐Yielding and Stereoselective Synthesis of α‐Trifluoromethylacrylic Acids.

An efficient strategy for a high-yielding and stereoselective synthesis of α-trifluoromethyl unsaturated carboxylic acids directly from the reactions of 3,3,3-trifluoropropanoic acid (CF3CH2COOH) with various aryl aldehydes in the presence of titanium tetrachloride (TiCl4) is reported here for the first time, which is a valuable expansion for the classical Knoevenagel reaction. Because these compounds may have potential applications in organic electronics and can be easily converted to the corresponding fluorinated alcohols and amino acids with excellent bioactivity, this route should be a good choice for the preparation of α-trifluoromethyl-containing derivatives.

Titanium‐Mediated Direct Carbon‐Carbon Double Bond Formation to α‐Trifluoromethyl Acids: A New Contribution to the Knoevenagel Reaction and a High‐Yielding and Stereoselective Synthesis of α‐Trifluoromethylacrylic Acids

AbstractAn efficient strategy for a high‐yielding and stereoselective synthesis of α‐trifluoromethyl unsaturated carboxylic acids directly from the reactions of 3,3,3‐trifluoropropanoic acid (CF3CH2COOH) with various aryl aldehydes in the presence of titanium tetrachloride (TiCl4) is reported here for the first time, which is a valuable expansion for the classical Knoevenagel reaction. Because these compounds may have potential applications in organic electronics and can be easily converted to the corresponding fluorinated alcohols and amino acids with excellent bioactivity, this route should be a good choice for the preparation of α‐trifluoromethyl‐containing derivatives.

ChemInform Abstract: High Diastereoselection in the Aldol Reaction of the Bistrimethylsilyl Enol Ether of Methyl Acetoacetate with 2-Benzyloxyhexanal: Synthesis of (-)-Pestalotin.

Aldol condensation of the bistrimethylsilyl enol ether of methyl acetoacetate, compound 2, with 2-benzyloxyhexanal 3c affords highly selectively (99:1) the syn-aldol adduct 4c in the presence of titanium tetrachloride. The stereocontrolled synthesis of (–)-pestalotin 7 has been achieved.

ChemInform Abstract: Synthesis of β- and γ-Carbolines and Their N-Oxides from 2(or 3)-Ethynylindole-3(or 2)-carbaldehydes.

Isoquinoline-type carbolines i.e. β-, and γ-carbolines and their N-oxides were synthesized from 2(or 3)-ethynylindole-3(or 2)-carbaldehydes, which were synthesized by electrophilic substitution with dichloromethyl methyl ether in the presence of titanium tetrachloride, or by lithiation with tert-butyllithium, followed by formylation with methyl formate.

Synthesis of imidazol-1-yl-acetic acid hydrochloride: A key intermediate for zoledronic acid

A convenient and practical synthesis of imidazol-1-yl-acetic acid hydrochloride was achieved via N-alkylation of imidazole using tert-butyl chloroacetate followed by a non-aqueous ester cleavage of the resulting imidazol-1-yl-acetic acid tert-butyl ester in the presence of titanium tetrachloride. The synthesized imidazol-1-yl-acetic acid hydrochloride was then utilized to prepare zoledronic acid.

TiCl4 and Grignard reagent-promoted ring-opening reactions of various epoxides: synthesis of γ-hydroxy-α,α-difluoromethylenephosphonates

A straightforward methodology for the synthesis of diethyl γ-hydroxy-α,α-difluoromethylenephosphonates is reported. In the presence of titanium tetrachloride, epoxide ring-opening reactions occurred upon treatment with lithium diethyl difluoromethylenephosphonate. When diethyl 3,4-epoxy-1,1-difluorobutylphosphonate was reacted with TiCl4 and Grignard reagents, the corresponding halohydrins were obtained in very good yields.

The Synthesis and Properties of Carbazole−Phenylazomethine Double Layer-Type Dendrimers

A new double layer-type dendrimer with carbazole as the outer layer and phenylazomethine as the inner layer of the dendron was synthesized using the Ullmann reaction and dehydration reaction in the presence of titanium tetrachloride. In this dendrimer, the carbazole units act as excellent hole-transporters, the phenylazomethine units act as metal assembling sites, and the combination of both units provides a thermally stable shell for which the 10% weight loss temperature was over 550 °C. The dendrimers were used as the hole-transporting layer in an OLED device. The OLED device performance increased when the generation of the carbazole increased, corresponding to the higher HOMO level. Additionally, the enhancement of the hole-transporting property was observed by simple complexation of the metal ions to the imine site. Next, the effect of the generation of phenylazomethine was observed and compared to the asymmetric-type carbazole-phenylazomethine dendrimers. When the generation of phenylazomethine incre...

Rapid Conversion of Hindered Arylsulfonates to Alkyl Chlorides with Retention of Configuration

Arylsulfonates of hindered secondary alcohols are converted to the corresponding alkyl chlorides very rapidly and in good yields in the presence of titanium tetrachloride at low temperatures. These reactions proceed with exclusive retention of configuration.

Synthesis and Chemical Degradation of Thermostable Polyamide with Imine Bond for Chemical Recycling

The mono-, di-, and triamino-substituted cyclic phenylazomethine (CPA) and diamino-substituted linear phenylazomethine (OPA) were synthesized in one-step via dehydration of aromatic amine and ketone in the presence of titanium tetrachloride. The linear and branched aromatic polyamides were prepared by the direct polycondensation of the di- or triamine monomers and various dicarboxylic acids in the presence of triphenyl phosphite and pyridine as condensation agents. Thermogravimetric analysis (TGA) revealed that the polymers had a high thermal stability. The temperature for a 10% weight loss determined by TGA was over 500 °C for some of the polymers. The hydrolysis property of the polymers was investigated using UV−vis spectroscopy. The spectra of the polymer solution in the presence of dilute sulfuric acid revealed that a simple and selective acid-catalyzed hydrolysis of azomethine bonds quantitatively occurred in mild conditions without cleavage of the amide bond, and more than 99% of the azomethine bonds were hydrated in less than 10 min at ambient temerature. The hydrolysis rate of the polymer was also determined. In polymer materials, these aromatic polyamides made it possible to relate high thermal stability with the decomposition property for effective chemical recycling.

Synthesis of Asymmetrically Arranged Dendrimers with a Carbazole Dendron and a Phenylazomethine Dendron

Asymmetrically arranged dendrimers with a carbazole dendron and a phenylazomethine dendron were synthesized by the combination of Ullmann reaction and a dehydration reaction in the presence of titanium tetrachloride. Stepwise complexation in the phenylazomethine dendron unit within these dendrimers and SnCl2 suggests a gradient in the electron density associated with the imine groups. The complexation of the dendrimer changes the HOMO/LUMO energy gap of the dendrimer. We show the dendrimers with higher generations have the larger HOMO values. The most electron-rich molecule, Cz3-DPA3, has the highest HOMO value of 5.35 eV and, accordingly, is expected to have the lowest barrier for the hole injection from the ITO electrode (4.6 eV) in OLEDs. However, for the HOMO energy levels of the carbazole dendrimer complex with SnCl2, the energy levels of the carbazoles did not change based on almost the same redox potentials as those of the dendrimers themselves. Using Cz3-DPA3 as a hole-transport layer (HTL), only complexation with metal ions results in the enhanced maximum luminescence from 4041 to 10 640 cd/m2 by only complexing with SnCl2 under the nonoptimized conditions. A complexation leads to a high EL efficiency because of the p-type-doped structure of the dendrimers as a hole-transport layer.

Novel carbazole dendrimers having a metal coordination site as a unique hole‐transport material

AbstractWe have synthesized novel carbazole dendrimers via the cyclotrimerization of aminophenylketones in the presence of titanium tetrachloride. These dendrimers have the ability to assemble metal ions such as Sn2+ and Eu3+ with no significant difference in their generation, suggesting the dendrimer with an interior with a small density up to the third generation. We show the dendrimers with higher generations have the higher HOMO values. The most electron rich molecule, the G3 dendrimer, has the highest HOMO value of −5.2 eV. However, for the HOMO energy levels of the carbazole dendrimer complex with Eu(OTf)3, the energy levels of the carbazoles did not change based on almost the same redox potentials as those of the dendrimers, themselves. Using the carbazole dendrimers and their europium complex, a homogeneous film was produced, which enhanced the performance of the electroluminescence device in comparison with only the dendrimer as the hole‐transporting layer. This approach was managed by a solution process, i.e., the spin‐coating method, without using the coevaporation technique based on the large equilibrium constants of the coordination of metal ions on the imine sites (K = 105 M−1).

Asymmetric Strecker Synthesis by Addition of Trimethylsilyl Cyanide to Aldehyde SAMP‐Hydrazones.

AbstractFor Abstract see ChemInform Abstract in Full Text.