Oxidative Acetylation of Tetramethyl Bisphenol‐F

Oxidative acetylation of tetramethyl bisphenol‐F (2) using two different reagents is described. The reaction of (2) with NaIO₄ in acetic anhydride furnished a novel triacetate (3) and its reaction with lead tetraacetate (LTA) in dry benzene resulted in the formation of a novel bis‐cyclohexadienone (4).     

A comprehensive review and a systematic approach to enhance the performance of improved cookstove (ICS)

Journal of Thermal Analysis and Calorimetry - The biomass has been the choice of the heat source for cooking purposes since ancient times. The inefficient combustion process in traditional...     

Morpholine Adsorbed on Silica Gel: A Novel and Mild Basic Catalyst for the Synthesis of α,β-Unsaturated Nitroalkenes

Summary.  Syntheses of α,β-unsaturated nitroalkenes have been carried out under mild condition using morpholine adsorbed on silica gel as a novel catalyst. Received February 14, 2000. Accepted March 28, 2000     

Microstructure change in poly(ethersulfone) films by swift heavy ions

PES membrane of thickness 25 μm was irradiated by Cl⁹⁺ ions of energy 100 MeV at IUAC, New Delhi. Microstructure changes due to exposure to high-energy ions were investigated by Fourier transform infrared (FTIR) and ultraviolet/visible (UV/vis) absorption spectroscopies, X-ray diffraction technique and by dynamic mechanical analysis (DMA). A significant loss of crystallinity is observed by the XRD data. Particle size or grain size calculated using Scherrer formula indicates measurable change in particle size of irradiated samples. The polymer chain scissions and structure degradations are expected to occur for irradiated samples. Optical properties of the films were changed due to irradiation that could be clearly seen in the absorption spectra. FTIR does not show the remarkable change in the irradiated samples, but there is some change in the surface roughness observed by AFM.     

Pd‐Colloids‐Catalyzed/Ag2O‐Oxidized General and Selective Esterification of Benzylic Alcohols

Palladium colloids obtained from the degradation of Hermann–Beller palladacycle proved to be an efficient catalytic system in combination with silver oxide as a selective oxidant for the oxidative esterification of differently substituted benzyl alcohols in MeOH as solvent. Excellent reactivity exhibited by the catalytic system also allowed the alcoholic coupling partner to be changed from MeOH to a wide range of alcohols having diverse functionalities. The mildness of the developed protocol also made it possible to employ propargyl alcohol as the coupling partner without any observation of any interference of the terminal alkyne. Selective oxidative coupling of a primary alcoholic functional group over secondary in the case of glycols and glycerols was also made possible using the developed catalyst system. To test the relevancy of Pd/Ag combined catalysis mixed Pd/Ag colloids were synthesized, characterized by TEM, XRD and XPS and applied to oxidative‐esterification successfully.     

Antagomirzymes: Oligonucleotide Enzymes That Specifically Silence MicroRNA Function

Many important cellular processes are regulated by small endogenous noncoding RNAs known as microRNAs (miRNAs). The precise molecular function of many miRNAs is unknown; different loss‐of‐function methods are required to gain insight into the biology of these small RNA molecules. Nucleic acid enzymes termed antagomirzymes are now shown to be valuable tools for the specific knockdown of miRNA in vitro and in vivo (see scheme).

     

Analysis of thermal,oxidative and cold flow properties of methyl and ethyl esters prepared from soybean and mustard oils

Oilseed crop with high oil content and promising ecological adaptability are potential sources for competitive biodiesel production. This study investigates the scope of utilizing biodiesel development through the methyl and ethyl ester from soybean and mustard oil as an alternative fuel. Methyl and ethyl esters of oils having different fatty acids compositions such as soybean (SOME and SOEE) and mustard oil (MUME and MUEE) were prepared by transesterification with methanol and ethanol in the presence of an alkali-KOH catalyst. The gas chromatographic (GC) analysis of oil samples revealed that primary fatty acid composition in soybean oil was linoleic acid (C_18:2, 51.93%), followed by oleic acid (C_18:1, 22.82%), palmitic acid (C_16:0, 11.56%), linolenic acid (C_18:3, 5.95%) and stearic acid (C_18:0, 4.32%). Whereas, the main components in mustard oil were erucic acid (C_22:1, 32.81%), oleic acid (C_18:1, 24.98%), eicosenoic acid (C_20:1, 10.44%), linolenic acid (C_18:3, 8.61%) and palmitic acid (C_16:0, 2.80%). The physicochemical properties (acid value, iodine value, calorific value, flash point, pour point etc.) of methyl and ethyl ester samples were estimated and found to be within the acceptable range of ASTM D6751 standards specifications. The prepared esters and oil samples were examined for cold flow properties by differential scanning calorimetry (DSC). Results revealed better cold flow properties for MUME (−2.55 °C) and MUEE (−3.10 °C) than SOME (3.21 °C) and SOEE (1.83 °C) due to more unsaturated fatty acid content in MU. Thermal and oxidative stability of samples was determined by thermogravimetric analysis (TG) and differential thermal analysis (DTA). The thermal and oxidative stability ranking of the samples was in the order of oil > methyl esters > ethyl esters.