Effect of epoxidized palm oil on the mechanical and morphological properties of a PLA–PCL blend

In this study, the effects of epoxidized palm oil (EPO) on the mechanical and morphological properties of a blend of two types of biodegradable polymer, poly(lactic acid) (PLA) and polycaprolactone (PCL), were investigated. The solution-casting process, with chloroform as a solvent, was used to prepare samples. Addition of EPO reduced the tensile strength and modulus but increased elongation at break for the PLA–PCL blend. The highest elongation at break was observed for the blend with 10 % (w/w) EPO content. Scanning electron microscopy (SEM) indicated that the fractured surface morphology of the PLA–PCL blend became more stretched and homogeneous in PLA–PCL–EPO. Possible interactions between the PLA–PCL blend and EPO were also characterized by use of Fourier-transform infrared (FTIR) spectroscopy. Thermal stability was studied by differential scanning calorimetry and thermogravimetric analysis. The results from FTIR and SEM revealed that the miscibility of the PLA–PCL blend was improved by addition of EPO.     

Theoretical study of hydrolysis of an imine oxime in aqueous solution and crystal structure and spectroscopic characterization of a platinum(II) complex containing the hydrolysis product

The hydrolysis of an imine oxime (ppeieoH) in neutral and acidic aqueous solutions was studied using DFT at the B3LYP/6-311G(d,p) level. The rate-determining step at the neutral and acidic aqueous solutions is the nucleophilic attack of the water molecules to the neutral or protonated imine C atom of ppeieoH. The activation energy is much lower in the acidic hydrolysis. The hydrolysis of ppeieoH results in the parent carbonyl oxime (inapH) and amine compounds with ΔG _cal values of 8.66 and 11.02 kJ mol^?1 in the neutral and acidic solutions, respectively. The hydrolysis of ppeieoH was observed experimentally during its reaction with K₂[PtCl₄] in an aqueous solution. The reaction yielded [PtCl(inap)(DMSO)], which contains only the hydrolysis product inap. The new platinum(II) complex was characterized spectroscopic techniques and X-ray diffraction. The platinum(II) ion is coordinated by chlorido, carbonyl oxime (inap), and DMSO ligands forming a distorted square-planar arrangement. The molecules of the platinum(II) complex were connected by weak non-conventional C–H···O and C–H···π hydrogen bonds.     

Determination of traces of iron and lead in food and water samples after preconcentration on multiwalled carbon nanotubes

A new method using multiwalled carbon nanotubes as an SPE adsorbent was developed for the sensitive determination of trace iron and lead prior to flame atomic absorption spectrometry analysis. Iron and lead as 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline chelates were adsorbed quantitatively on multiwalled carbon nanotubes at a pH of 6.0 and easily eluted with 10 mL 1 M HNO3. The influences of matrix ions were also examined. The LOD values for iron and lead were calculated as 1.3 and 2.9 microg/L, respectively. Validation of the presented procedure was performed by the analysis of TMDA 54.4 fortified lake water and HR-1 Humber River sediment certified reference materials. The method was successfully applied to the determination of trace iron and lead in real environmental samples, and excellent results were achieved.     

Silver-catalyzed formal inverse electron-demand Diels-Alder reaction of 1,2-diazines and siloxy alkynes

A highly effective silver-catalyzed formal inverse electron-demand Diels-Alder reaction of 1,2-diazines and siloxy alkynes has been developed. The reactions provide ready access to a wide range of siloxy naphthalenes and anthracenes, which are formed in good to high yields, under mild reaction conditions, using low catalyst loadings.     

Profile of Parkia speciosa Hassk Metabolites Extracted with SFE using FTIR‐PCA Method

A rapid identification, classification and discrimination tool, using Fourier Transform Infrared (FTIR) spectroscopy combined with Principal Component Analysis (PCA), was developed and applied to determine the profile of the Supercritical Fluid Extraction (SFE) of Parkia speciosa seeds under various temperature and pressure conditions (313, 323, 333, 343, 353 and 363 K and 20.68, 27.58, 34.47, 41.37, 48.26, and 55.16 MPa). The separation and identification of the compounds was carried out by Gas Chromatography coupled with Time of Flight Mass Spectrometry (GC/TOF‐MS). This technique has made it possible to detect the variability obtained under different SFE conditions and the separation of different chemical compounds in P. speciosa seeds. The FTIR‐PCA results were verified by GC/TOF‐MS, and the FTIR‐PCA method successfully identified the unsaturated carboxylic acids with the highest percentage area under the different conditions.     

Novel and enantioselective syntheses of (R)- and (S)-3-hydroxy-4-(2,4,5-trifluorophenyl)butanoic acid: a synthon for sitagliptin and its derivatives

A new synthetic strategy for (R)- and (S)-3-hydroxy-4-(2,4,5-trifluorophenyl)butanoic acid, a building block in the preparation of sitagliptin and its derivatives, was developed. Pd(OAc)₂ catalyzed coupling of 2,4,5-trifluoro-1-iodobenzene with allyl alcohol gave 3-(2,4,5-trifluorophenyl)propanal in a yield of 95%. l-Proline catalyzed reaction of the 3-phenylpropanal (in only 1.2 molar equiv) with nitrosobenzene followed by reduction with NaBH₄ and Pd/C catalyzed hydrogenation gave (R)-3-(2,4,5-trifluorophenyl)propane-1,2-diol with >99% ee and 65% yield. Selective tosylation of primary hydroxyl group of the 1,2-propandiol unit followed by cyanide displacement afforded (R)-3-hydroxy-4-(2,4,5-trifluorophenyl)butanenitrile (80%). The nitrile was converted to the title β-hydroxy acid under basic hydrolysis in a yield of 90%. Thus, (R)-3-hydroxy-4-(2,4,5-trifluorophenyl)butanoic acid was prepared enantioselectively from the starting material in four steps and 45% overall yield. The reaction sequence was repeated with d-proline as the catalyst to give (S)-3-hydroxy-4-(2,4,5-trifluorophenyl)butanoic acid in 45% overall yield and >99% enantiomeric excess.     

Preparation and photovoltaic property of a new hybrid nanocrystalline SnO2/Polypyrrole p–n heterojunction

Hybrid photovoltaic structures based on transparent conductive SnO₂ and electrically conductive polypyrrole (PPy) were prepared. Nanocrystalline SnO₂ is considered an n-type barrier and window layer on p-type PPy layer in cell structures. The surface morphology and thickness of the layers were studied using scanning electron microscopy. The optical absorbance data showed an increase of absorbance in contrast with PPy and SnO₂. There was a red shift in absorbance wavelengths and a decrease in band gaps for the prepared PV structures. To investigate the electrical properties of the obtained structures, current-voltage characteristic was measured. The best structure showed an open-circuit voltage of 0.170?V, a short-circuit current density of 0.017?mA/cm², a fill factor of 0.36 and power conversion efficiency of 0.076.     

Studies on the reactions of cyclic oxalyl compounds with hydrazines or hydrazones : Synthesis and reactions of 4‐benzoyl‐1‐(3‐nitrophenyl)‐5‐phenyl‐1H‐pyrazole‐3‐carboxylic acid

The 1H‐pyrazole‐3‐carboxylic acid 2 , obtained from the furan‐2,3‐dione 1 and N‐Benzylidene‐N'‐(3‐nitrophenyl) hydrazine, was converted via reactions of its acid chloride 3 with various alcohols or N‐nucleo‐philes into the corresponding ester or amide derivatives 4 or 5 , respectively. Nitrile 6 and anilino‐pyrazole acid 7 derivatives of 2 were also obtained by dehydration of 5a in a mixture of SOCl₂ with DMF and reduction of 2 with sodium polysulphide, respectively. While cyclocondensation reactions of 2 or 7 with phenyl hydrazine or hydrazine hydrate and 6 with only anhydrous hydrazine lead to derivatives of pyrazolo[3,4‐d]‐pyridazinone 8 and pyrazolo[3,4‐d]pyridazine amine 9 , respectivel. The reaction of 2 with 2‐hydrazinopyri‐dine provided hydrazono‐pyrazole acid derivative 10 , which was decarboxylated to give hydrazono‐pyra‐zole derivative 11 . Pyrazolo[4,3‐d]oxazinone 12 and 2‐quinolyl pyrazolo[3,4‐d]pyridazine 13 derivatives were also prepared by cyclocondensation reactions of 2 with hydroxylamine hydrochloride and 7 with acetaldehyde, respectively.     

Novel Methods for the Synthesis of 4‐Arylisoquinolinium Perchlorates and 4‐Arylisoquinolin‐1‐ones

2‐Benzylamino‐1‐phenyl‐ethanones 1 were converted to the corresponding isoquinolinium perchlorates 2 in high yields using 70% HClO₄‐FeCl₃ mixture as a cyclization and oxidation reagent. A mild and high yielding method for the oxidation of perchlorates 2 to isoquinolin‐1‐ones 3 involving the treatment of 2 with KOH and K₃[Fe(CN)₆] in THF‐H₂O two‐phase system at room temperature was developed. Compounds 2a–g were shown to be disproportionate to 3 and the corresponding 1,2‐dihydroisoquinoline 4 in the presence of base, which in turn is oxidized by K₃[Fe(CN)₆] to 2.     

The relationship between refractive index-energy gap and the film thickness effect on the characteristic parameters of CdSe thin films

CdSe thin films were deposited on glass substrates using Successive Ionic Layer Adsorption and Reaction (SILAR) method at room temperature and ambient pressure. The relationship between refractive index and energy bandgap was investigated. The film thickness effect on the structural, morphological, optical and electrical properties of CdSe thin films was investigated. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies showed that all the films exhibit polycrystalline nature with hexagonal structure and are covered well with glass substrates. The crystalline and surface properties of the films improved with increasing film thickness. The optical absorption studies revealed that the films are found to be a direct allowed transition. The energy bandgap values were changed from 1.93 to 1.87 eV depending on the film thickness. The electron effective mass (m_e^?/m_o), refractive index (n), optical static and high frequency dielectric constant (ε_o, ε_∞) values were calculated by using the energy bandgap values as a function of the film thickness. The resistivity of the films changed between 10⁶ and 10² Ω-cm with increasing film thickness at room temperature.