Addition Of Acetylacetone Research Articles

Synthesis of Bifunctional Amine-Squaramide Organocatalysts Derived from 3-((Dimethylamino)methylene)camphor.

Four bifunctional, noncovalent amine-squaramide organocatalysts were prepared from camphor in five steps. The stereochemistry of the prepared catalysts was thoroughly analyzed using various spectroscopic techniques. Their organocatalytic activity was investigated in the Michael addition of acetylacetone to trans-β-nitrostyrene. The addition product was formed in complete conversion and with an enantioselectivity of up to 77% ee. In the reactions catalyzed by the 2-exo-3-endo catalysts, the major (S)-enantiomer was formed, whereas in the presence of 2-endo-3-endo catalysts, the (R)-enantiomer was formed as the major product.

Non-hydrolytic sol-gel synthesis of BaTiO3 nano-powder: Effect of calcination temperature and modified titanium source on particles

In this study, BaTiO3 nanopowders were prepared by non-hydrolytic sol-gel (NHSG) method using barium acetate and tetrabutyl titanate (TBT) as precursors and acetylacetone (Hacac) as additive. The effects of acetylacetone modification and calcination temperature on nanoparticle size and crystalline phase were evaluated. The products were analysed by SEM, TEM, DSC/TG, FTIR, XRD, Raman. FTIR analysis showed the formation of Ba-O-Ti bond at the sol stage of the NHSG method. DSC/TG and XRD analyses showed that BaTiO3 was produced at 500 ℃. According to SEM/TEM, the particle size of the powder becomes larger as the temperature increases, meanwhile the addition of acetylacetone can make the final product particle size decrease. Raman analysis showed that BaTiO3 has the presence of tetragonal phase, so the crystalline phases of the product and impurities were analysed by XRD refinement, and the results showed that the relative content of tetragonal phase of BaTiO3 was linearly correlated with the calcination temperature.

The Electrophoretic Deposition of Nanopowders Based on Yttrium Oxide for Bulk Ceramics Fabrication

In the present work, a study was carried out to investigate the key factors that determine the uniformity, mass, thickness, and density of compacts obtained from nanopowders of solid solutions of yttrium and lanthanum oxides ((LaxY1−x)2O3) with the help of the electrophoretic deposition (EPD). Nanopowders were obtained by laser ablation of a mixture of powders of yttrium oxide and lanthanum oxide in air. The implemented mechanisms of the EPD and factors of stability of alcohol suspensions are analyzed. It has been shown that acetylacetone with a concentration of 1 mg/m2 can be used as a dispersant for stabilization of isopropanol suspensions of the nanoparticles during the EPD. It was shown that the maximum density of dry compacts with a thickness of 2.4 mm reaches 37% of theoretical when EPD is performed in vertical direction from a suspension of nanopowders with addition of acetylacetone.

Synthesis and Catalytic Activity of Organocatalysts Based on Enaminone and Benzenediamine Hydrogen Bond Donors

A total of 24 novel organocatalysts based on (S)-quininamine as a chiral tertiary amine and on enaminone or 1,2-benzenediamine as hydrogen bond donors were synthesized. The enaminone-type catalysts were prepared by the transamination of N,N-dimethyl enaminones with (S)-quininamine (9 examples) and the 1,2-benzenediamine-type catalysts were prepared in 3 steps from (S)-quininamine and ortho-fluoronitrobenzene derivatives (15 examples). Their organocatalytic activity was evaluated in the Michael addition of acetylacetone to trans-β-nitrostyrene. Enantioselectivities of up to 72% ee were observed.

Experimental and computational studies on the Cinchona anchored calixarene catalysed asymmetric Michael addition reaction.

Lower-rim Cinchona anchored calix[4]arene cationic catalysts were developed for asymmetric Michael addition of acetylacetone to β-nitrostyrenes. The desired Michael adducts were formed with high yields and enantioselectivities. Density functional theory investigations throw light on the catalyst-substrate interaction and the reaction mechanism.

DABCO Catalyzed Efficient Addition of Acetyl Acetone on Isatins Under Neat Condition to Afford 3-hydroxy-3-((E)-2-hydroxy-4-oxopent-2-enyl) indolin-2-one Derivatives

We have demonstrated DABCO catalyzed efficient addition of Acetyl acetone on isatins under neat condition to afford 3-hydroxy-3-((E)-2-hydroxy-4-oxopent-2-enyl)indolin-2-one derivatives. The developed method as found applicable for different structurally diverse isatin electrophiles which has tolerated different functional groups in the reaction to afford Aldol addition products with high isolated yields. The use of green organocatalyst DABCO, mild reaction conditions and catalyst-free nature under neat conditions makes the procedure interesting alternative over the previous methods. Moreover the present protocol provides rapid and easy access for functionally diverse 3-hydroxy-3-((E)-2-hydroxy-4-oxopent-2-enyl) indolin-2-one derivatives, which might be useful for further chemical transformations to prepare a variety of compounds desirable for different applications.

A novel isosteviol-based bifunctional squaramide organocatalyst for enantioselective Michael addition of acetylacetone to nitroolefins.

Chiral amine-squaramide is a kind of effective hydrogen bond donor bifunctional catalyst to promote many asymmetric transformations. In this paper, novel chiral tertiary amine-squaramide derived from the natural product of the stevioside was developed and applied into the asymmetric Michael addition of acetylacetone to nitroolefins. This asymmetric reaction performed well, and a series of enantiomerically enriched compounds were obtained in high yields (up to 96%) with excellent enantioselectivities (up to 99% ee).

Synthesized TiO2 Mesoporous by Addition of Acetylacetone and Graphene for Dye Sensitized Solar Cells

This study mixed acetylacetone (Acac, 1, 2, and 3 mL) and graphene powder (GP, 0 wt.%, 0.001 wt.%, 0.003 wt.% and 0.005 wt.%) with TiO2 mesoporous (TiO2 powders: 20 g and particle size ~30 nm) to enhance the optoelectronic performances of dye sensitized solar cells (DSSC). Sponge-like structure TiO2 mesoporous layers is a requirement for obtaining high efficiency DSSC, which ia synthesized by spin-coating techniques. The dense TiO2 blocking layer (using peroxo-titanium complex) has a uniform, dense structure and completely adheres to the substrates to avoid charge recombination. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses of the TiO2 films display the anatase type phase with preferred orientation along the (101) direction. After being ball milled, the TiO2 mesoporous particle size almost remains unchanged. For mixing the Acac with TiO2, the Raman intensity relatively increased, and the band gap energy (Eg) value decreased from 3.223 eV (for pure TiO2) to 3.076 eV (for 2 mL Acac). Raman spectroscopy is used to evaluate the GP elements. It can be seen the intensity ratio (ID/IG) and (I2D/IG) was enhanced when the GP concentration increased. Using mixed Acac 2 mL and GP 0.003 wt.% with a TiO2 mesoporous, led to increases in the open circuit voltage (VOC), short circuit current density (JSC) and fill factor (FF). If a fluorine-doped tin oxide is used instead of an indium tin oxide glass substrate, the photovoltaic efficiency of DSSC increases from 5.45% to 7.24%.

Low catalyst loading enabled organocatalytic synthesis of chiral bis-heterocyclic frameworks containing pyrazole and isoxazole.

The organocatalytic asymmetric synthesis of enantiopure bis-heterocyclic molecules containing pyrazole and isoxazole under mild reaction conditions has been reported via a low-catalyst loading Michael addition reaction of pyrazolyl nitroalkenes with 1,3-dicarbonyl derivatives. 4-Substituted pyrazole derivatives were obtained in 60-87% yields and with 82-97% ee. These pyrazolyl derivatives are further transformed into chiral bis-heterocyclic derivatives in up to 82% yields and up to 99% ee. The synthesized pyrazole and isoxazole based bis-heterocyclic derivatives are potential bio-active molecules expected to have significant applications. Additionally, the synthesis of these bis-heterocycles can efficiently be carried out in one pot without any loss of enantiopurity, which further adds to its significance.

Synthesis, characterization and catalytic performance in enantioselective reactions by mesoporous silica materials functionalized with chiral thiourea-amine ligand

Chiral heterogeneous catalysts have been synthesized by grafting of silyl derivatives of (1R, 2R)- or (1S, 2S)-1,2-diphenylethane-1,2-diamine on SBA-15 mesoporous support. The mesoporous material SBA-15 and so-prepared chiral heterogeneous catalysts were characterized by a combination of different techniques such as X-ray diffractometry (XRD), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), and Brunauer–Emmett–Teller (BET) surface area. Results showed that (1R, 2R)- and (1S, 2S)-1,2-diphenylethane-1,2-diamine were successively immobilized on SBA-15 mesoporous support. Chiral heterogeneous catalysts and their homogenous counterparts were tested in enantioselective transfer hydrogenation of aromatic ketones and enantioselective Michael addition of acetylacetone to β-nitroolefin derivatives. The catalysts demonstrated notably high catalytic conversions (up to 99%) with moderate enantiomeric excess (up to 30% ee) for the heterogeneous enantioselective transfer hydrogenation. The catalytic performances for enantioselective Michael reaction showed excellent activities (up to 99%) with poor enantioselectivities. Particularly, the chiral heterogeneous catalysts could be readily recycled for Michael reaction and reused in three consecutive catalytic experiments with no loss of catalytic efficacies.

Stable and efficient air-processed perovskite solar cells employing low-temperature processed compact In2O3 thin films as electron transport materials

Abstract Perovskite solar cells (PSCs) have achieved remarkable power conversion efficiencies (PCEs) owing to their extraordinary optoelectronic properties. Electron transporting layer (ETL) has been proved to have a significant influence on the photovoltaic performance and stability of cell devices. Herein, for the first time, we prepare a low-temperature processed compact In2O3 film derived from a highly stable modified indium precursor solution as a promising ETL for stable and efficient air-processed PSCs. The addition of acetylacetone as a chelation ligand in the solution effectively inhibits the hydrolysis reactions by chelating In3+, thus contributing to the formation of compact In2O3 film at a low temperature of 200 °C. Dense CH3NH3PbI3 perovskite films with many microns-scale grains are fabricated using a scalable doctor-blade method under a harsh ambient condition (relative humidity of 40–50%). Using the proposed compact In2O3 film as ETL, the electron extraction and charge transport at the ETL/perovskite interface are significantly improved. As a result, the air-processed PSC based on compact In2O3 film delivers a champion PCE of 13.97%, greatly outperforming the device with a pristine In2O3 film (9.81%). In addition to high efficiency, the PSC incorporating proposed compact In2O3 film exhibits an excellent long-term stability, maintaining 94% of its initial PCE after stored in air for 31 days. This study demonstrates the feasibility of fabricating stable and efficient air-processed PSCs using low-temperature processed In2O3 ETL, which is expected to have a positive impact in the manufacturing community of solution-processed In2O3 film as well as air-processed PSCs.

Improvement of Sensing Performance of Impedancemetric C₂H₂ Sensor Using SmFeO₃ Thin-Films Prepared by a Polymer Precursor Method.

A sensitive an impedancemetric acetylene (C2H2) gas sensor device could be fabricated by using perovskite-type SmFeO3 thin-film as a sensor material. The uniform SmFeO3 thin-films were prepared by spin-coating and focusing on the effects of polymer precursor solutions. The prepared precursors and thin-films were characterized by means of thermal analysis, Fourier-transform infrared spectroscopy, ultraviolet–visible spectroscopy, X-ray diffraction analysis, scanning electron microscopy and X-ray photoelectron spectroscopy. It was found that particle growth and increase in homogeneity of the prepared thin-film could be accelerated by the addition of acetyl acetone (AcAc) as a coordination agent in the polymer precursor solution. Moreover, the highly crystallized thin-film-based sensor showed good response properties and stabilities to a low C2H2 concentration between 0.5 and 2.0 ppm.

Synthesis of 2,3-Bis[amino(benzylsulfanyl)methylidene]butanedinitrile and 2-(Benzylsulfanyl)pyridine-3-carbonitrile derivatives

The alkylation of cyanothioacetamide with benzyl chloride in DMF in the presence of 10% aqueous potassium hydroxide afforded 2,3-bis[amino(benzylsulfanyl)methylidene]butanedinitrile. Analogous reaction with addition of acetylacetone or its 3-methyl derivative led to the formation of 2-benzylsulfanyl-4,6-dimethylor -4,5,6-trimethylpyridine-3-carbonitrile.

Preparation of Rod-like Aluminum Doped Zinc Oxide Powders by Sol-gel Technique Using Metal Chlorides and Acetylacetone Precursors

Al-doped ZnO (AZO) powders were prepared by using metal chloride precursors and the sol-gel technique. IR peaks observed at 1590 cm-1 and 1620 cm-1 indicated the formation of metal chelate as a consequence of the addition of acetylacetone to the metal chloride solution. TG-DSC analysis of the AZO gels confirmed the formation of metal chelate as evidenced by the development of several weight loss peaks accompanied by the introduction of new endothermic peaks. The resulting AZO gels were annealed at 500, 600, and 800 °C to study the effect of annealing temperature. XRD and SEM results showed that crystallization of AZO gels takes place around 600 °C. Hexagonal wurtzite structure was identified as the main phase for all the samples. In addition, small shift of the XRD (002) peak coupled with XPS results from the AZO powders confirmed the successful doping of the ZnO powders. Micron sized rod-like AZO powders were uniform in dimension and morphology and remained stable even at 800 °C.

New bifunctional carbohydrate-like thiourea derivatives – design and first application in organocatalysis

From easily available aminopyran and aminooxepane derivatives and 2,5-bis(trifluoromethyl)phenyl isothiocyanate the corresponding thiourea derivatives were prepared. One compound was further modified by introducing a tertiary amino group. The four catalysts were then examined as catalysts in a Michael addition of acetylacetone to β-nitrostyrene. A 1:1 mixture of one of these thioureas with an (S)-prolinol derivative was also tested as catalyst, but no synergetic effect was found. The best yield achieved was 88% and the highest ee amounted to 39%. In a preliminary experiment, the aldol reaction of acetone with isatin was investigated. One catalyst provided the expected aldol product in low yield, but in excellent enantioselectivity.

Novel and highly efficient bifunctional calixarene thiourea derivatives as organocatalysts for enantioselective Michael reaction of nitroolefins with diketones

New bifunctional calixarene thiourea organocatalysts were synthesized and applied in catalytic asymmetric Michael addition of acetylacetone to various nitroolefins at room temperature. The corresponding adducts were obtained in good to excellent yields with excellent enantioselectivities (up to 92% ee). The present research demonstrates the advantages of incorporating two stereocontrolling structures into a single catalyst. Notably, it offers a simple and convenient doubly stereocontrolled approach for the catalytic asymmetric synthesis of a chiral organic molecule.

Decrypting Transition States by Light: Photoisomerization as a Mechanistic Tool in Brønsted Acid Catalysis.

Despite the wide applicability of enantioselective Brønsted acid catalysis, experimental insight into transition states is very rare, and most of the mechanistic knowledge is gained by theoretical calculations. Here, we present an alternative approach (decrypting transition state by light = DTS-hν), which enables the decryption of the transition states involved in chiral phosphoric acids catalyzed addition of nucleophiles to imines. Photoisomerization of double bonds is employed as a mechanistic tool. For this class of reactions four pathways (Type I Z, Type I E, Type II Z, Type II E) are possible, leading to different enantiomers depending on the imine configuration (E- or Z-imine) and on the nucleophilic attack site (top or bottom). We demonstrated that the imine double bond can be isomerized by light (365 nm LED) during the reaction leading to a characteristic fingerprint pattern of changes in reaction rate and enantioselectivity. This characteristic fingerprint pattern is directly correlated to the transition states involved in the transformation. Type I Z and Type II Z are demonstrated to be the competing pathways for the asymmetric transfer hydrogenation of ketimines, while in the nucleophilic addition of acetylacetone to N-Boc protected aldimines Type I E and Type II E are active. Accelerations on reaction rate up to 177% were observed for ketimines reduction. Our experimental findings are supported by quantum chemical calculations and noncovalent interaction analysis.

Synthesis of highly hydrophobic rutile titania-silica nanocomposites by an improved hydrolysis co-precipitation method

Highly hydrophobic rutile titania-silica nanocomposites were synthesized by an improved hydrolysis co-precipitation method using low-cost sodium metasilicate and titanium oxysulfate (TiOSO4) as precursors, followed sequentially by calcination at 800°C and modification with trimethylchlorosilane (TMCS). It was found that the resulting TiO2-SiO2 nanocomposites had a Ti/Si molar ratio of 5:1 and exhibited single-phase rutile with a specific surface area of 269m2g−1. The addition of acetylacetone (AcAc) during the hydrolysis co-precipitation process played a key role in the growth of well-ordered TiO2-SiO2 crystallites since the hydrolysis rate of TiOSO4 might be retarded due to the complexation of AcAc to the Ti atoms in TiOSO4. The TMCS-modified TiO2-SiO2 nanocomposites exhibited a high root-mean-square (RMS) roughness of 22nm and good hydrophobicity with a static contact angle of 143.7°, highlighting its potential application as a filler in exterior wall coatings.

ALUMINA MATRIX WITH CONTROLLED MORPHOLOGY FOR COLORED SPECTRALLY SELECTIVE COATINGS

This study presents the results obtained in tailoring thin films of alumina, deposited onto aluminium substrates by spray pyrolysis, at 250.C, using AlCl3 solutions (0.15M) in a water:ethanol (1:1) solvent mixture. As morphology controlling agents, acetylacetone and maleic acid based copolymers are added in the precursors solutions. The precursors systems are analyzed by FTIR spectroscopy and the surface morphology of alumina thin films is investigated by atomic force microscopy. The addition of hydrophilic copolymer in precursors solution favors the development of regular open structures, while fractured large open structures are obtained when hydrophobic copolymer is used. The addition of acetylacetone in spraying solution leads to irregular large open structures. Combined additive systems (acetylacetone and hydrophylic/hydrophobic copolymers) have a complex influence and can be a tool in tailoring the morphology of the alumina thin films, as suitable matrix for further infiltration of red (Fe2O3) and gray-green (CuxS) pigments and development of colored solar selective absorber coatings with promising optical performances. Thus, spectral selectivities (S) of 3.4 - 4.07 are obtained for red absorber coatings, while for gray-green absorber coatings spectral selectivities are slightly lower (S = 2.35 - 2.7).

Regioselectivity observed in manganese(III) acetate mediated addition of acetylacetone to various alkenes: mechanistic and theoretical studies

Various alkenes substituted at the 1,2-positions by 2-thiophenyl, 3-thiophenyl, and phenyl substituted by electron-withdrawing and electron-donating groups were treated with acetylacetone in the presence of Mn(OAc)3 in acetic acid. In cases where the thiophene ring was connected at the C-2 carbon atom to the double bond, a single regioisomer was formed whereas in case of substitution at the C-3 positions two regioisomers were formed. Stilbene derivatives also gave two regioisomers under the same reaction conditions. However, 1-methoxy-4-(4-nitrostyryl)benzene provided a single cycloaddition product. The observed regioselectivity was discussed in terms of atomic charge distribution on the olefinic double bond carbon atoms. Furthermore, activation barriers for transition states were calculated.