Biodiesel is an eco-friendly alternative diesel fuel prepared from domestic renewable resources i.e. vegetable oils and animal fats. In this process, biodiesel is produced by transesterification of triglycerides present in animal fat or vegetable oils, by displacing glycerine with a low molar mass alcohol using homogeneous or heterogeneous catalysis. The resulting ester, after mixing with diesel fuels, has physicochemical properties similar to those of conventional fuels. In this work, the batch process of biodiesel production has been studied using tallow fat as raw material with methanol and a heterogeneous catalyst. The quality of the produced biodiesel was evaluated by the determination of important properties, such as viscosity, flash point, cetane number, oxidation stability, glycerine content, acid value, etc. The produced biodiesel was found to demonstrate fuel properties within the ranges recommended by the ASTM D6751.
Nanocapsules containing hexadecane or paraffin as core materials and polystyrene as a shell were produced in a new method through emulsifier-free miniemulsion polymerization using 2,2' azobis (2-amidinopropane) dihydrochloride (V-50) as a cationic ionizable water-soluble initiator. The effect of some parameters such as hexadecane or paraffin amounts and polymerization duration on morphology and thermal properties of resulting nanocapsule particles was studied. Transmission electron microscopy (TEM) showed that the products had latex particles having a size range of about 200-700 nanometer and both nanocapsules with core-shell morphology and solid particles. The phase change temperature and phase transition heat of the produced nanocapsules were determined by differential scanning calorimetric (DSC) analyses. Thermogravimetric analysis (TGA) was also used to prove the capsulation and to determine the amount of hexadecane or paraffin in the nanocapsules.
Homo-and copolymers of vinyl esters including vinyl acetate (VAc) and vinyl benzoate (VBz) were synthesized via the reverse iodine transfer radical polymerization technique. Polymerization was carried out in the presence of iodine as the in situ generator of the transfer agent and 2,2 ′ -azobis(isobutyronitrile) as the initiator at 70 ∘ C. Reverse iodine transfer radical homopolymerization of VAc and VBz led to conversions of 76 and 57%, number-average molecular weights of 8266 and 9814 g mol −1 and molecular weight distributions of 1.58 and 1.49, respectively. The microstructure of the synthesized polymers was investigated in detail using gel permeation chromatography, 1 H NMR, 13 C NMR and distortionless enhancement of polarization transfer (135 ∘ decoupler pulse) techniques. Relatively narrow molecular weight distribution and controlled and predictable trend of molecular weight versus conversion were observed for the synthesized polymers, showing that reverse iodine transfer radical homo-and copolymerization of VAc and VBz proceeded with controlled characteristics. Results of molecular weight and its distribution along with the 1 H NMR spectra recorded for homo-and copolymers indicated that side reactions can occur during the course of polymerization with a significant contribution when VAc, even in a small amount, was present in the reaction mixture. This can result in polymer chains with aldehyde dead end and broadening of the molecular weight distribution.
A convenient one-pot, three-component reaction of aromatic aldehydes, 6-amino-1,3-dimethyluracil and active methylene compounds in the presence of Zr(HSO4)4 as a heterogeneous catalyst, under solvent-free conditions brings a very simple and highly efficient method for the preparation of pyrimido[4,5-b]quinolines, pyrimido[5',4':5,6]pyrido[2,3- d]pyrimidines, indeno[2',1':5,6]pyrido[2,3-d]pyrimidines and a new class of pyrimidinedione derivatives in excellent yields. This approach is general and provides several advantages such as simple reaction set-up, very mild reaction conditions, high yields, recyclability of the catalyst and environmentally friendly benign.
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