Pengembangan Novel Grafik Elektronik pada Materi Reaksi Radikal Bebas sebagai Media Suplemen Pembelajaran

This research was aimed to produce a valid electronic graphic novel on free radical reaction subject and to find out the student’s response to the developed product. This research employed Research & Development (R&D) method by using Thiagarajan’s 4D model with modification, in which applied only three of four steps in 4D model. The developed product was validated by experts. The responses toward developed product were collected from the students of Chemistry Education FKIP Untan who have taken organic chemistry course. Data collection tools used were validation sheets and student’s response questionnaires on the developed product. The validation’s result from the experts showed that the developed product was very proper in terms of content, presentation, linguistic, and graphic aspects with consecutive total scores of 94.0%, 95.0%, 89.0%, and 100,00% respectively. The results of the student’s responses in small group trials and in large group trials were of 82.5% with high category and of 83.2% with very high category, respectively. Thus, this electronic graphic novel on radical reaction has very good potential as a learning media to attract students to learn free radical reaction and its application in daily life.

Novel Conditioner For Efficient Dewaterability And Modification of Oily Sludge With High Water Content

The Oily sludge with high water content (OS) was dewatered, modified and converted into solid fuel by a novel chemical conditioner (OSO-101). The effect of OSO-101 dosage on the dewaterability of OS was studied, showing that OSO-101 dosage of 15% (wt.) could achieve the best dewaterability efficiency of OS (98.18%). Meanwhile, compared with some conventional conditioners, OSO-101 developed by our team was more effective in improving OS dewaterability efficiency. And OSO-101 may have free radical reaction, polar reaction and redox reaction with petroleum hydrocarbons in OS, thereby polymerizing and forming condensed solid structures. The calorific value change of OS after conditioning, heavy metal content and dioxins content of fly ash leached from incinerated product were measured for resource analysis and environmental assessment. Results showed that the resultant OS fuel blocks had extremely low content of heavy metals, dioxins and other toxic and hazardous substances leached from fly ash, thereby no secondary treatment and fully meeting environmental protection emission standards. Additionally, OSO-101 had certain economic rationality, and could effectively recover the calorific value contained in OS. This research is expected to provide new insights for efficient dewaterability and modification of OS, as well as subsequent resource utilization and harmless treatment, bringing potential environmental and economic benefits.

Fast Antioxidant Reaction of Polyphenols and Their Metabolites

The negative correlation between diets rich in fruits and vegetables and the occurrence of cardiovascular disease, stroke, cancer, atherosclerosis, cognitive impairment and other deleterious conditions is well established, with flavonoids and other polyphenols held to be partly responsible for the beneficial effects. Initially, these effects were explained by their antioxidant ability, but the low concentrations of polyphenols in tissues and relatively slow reaction with free radicals suggested that, instead, they act by regulating cell signalling pathways. Here we summarise results demonstrating that the abandonment of an antioxidant role for food polyphenols is based on incomplete knowledge of the mechanism of the polyphenol-free radical reaction. New kinetic measurements show that the reaction is up to 1000 times faster than previously reported and lowers the damaging potential of the radicals. The results also show that the antioxidant action does not require phenolic groups, but only a carbon-centred free radical and an aromatic molecule. Thus, not only food polyphenols but also many of their metabolites are effective antioxidants, significantly increasing the antioxidant protection of cells and tissues. By restoring an important antioxidant role for food polyphenols, the new findings provide experimental support for the advocacy of diets rich in plant-derived food.

AIBN-initiated direct thiocyanation of benzylic sp3 C–H with N-thiocyanatosaccharin

The direct thiocyanation of benzylic compounds was described, and benzyl thiocyanates were synthesized using readily available alkanes as the substrates.

Cooxidation of Dibenzalacetone with Oxalic Acid by Pyrazinium Chlorochromate

Oxidation of dibenzalacetone with pyrazinium chlorochromate in presence of oxalic acid has been studied at 313 K. Various reaction parameters such as effect of varying oxidant, substrate, Hydrogen ion concentration, catalyst, solvent composition, ionic strength, effect of Mn2+, effect of Al3+ and effect of temperature were studied to determine the kinetics of the reaction. Our study revealed that the reaction followed first order dependence with respect to oxidant and catalyst. The reaction followed fractional order kinetics with respect to substrate and H+. Increase in ionic strength was found to have no effect on the reaction rate and decrease in the dielectric constant of the medium decreases the reaction rate. Increase in the concentration of manganous sulphate retarded the reaction rate which confirmed the two-electron transfer involved in the mechanism. There was no possibility of free radical mechanism, which was confirmed by the addition of acrylonitrile shows no significant effect on the reaction rate indicating the non-involvement of free radical reaction.. Based on the experimental observations a mechanism and rate law has been derived. Moreover, the oxidation product was found to be chalcone epoxide, which was characterized by IR spectrum.

PHYTOCHEMICAL ANALYSIS AND ANTIOXIDANT ACTIVITY OF PURNAJIWA FRUIT EXTRACT (Euchresta horsfieldii (Lesch.) Benn.)

Antioxidant is a chemical compound that could give one or more electrons to inhibit the free radical reaction. One of the plants that potentially produce antioxidants is purnajiwa (Euchresta horsfieldii (Lesch.) Benn.). The research was conducted using the fruit of purnajiwa. The purpose of this study is to know antioxidant activity from purnajiwa fruit using the DPPH method and measured by UV-Vis spectrophotometry. The extract of purnajiwa fruit gained by the maceration method using 96% ethanol solvent. The results of phytochemistry screening found out that the extract contains flavonoid, alkaloid, saponin, tannin, and terpenoid. According to flavonoid testing using quercetin, the results obtained from purnajiwa extract contained flavonoid of 1,651 mg QE/g. The activity test of antioxidants quantitatively by DPPH using UV-Vis spectrophotometry found out that purnajiwa extract has IC50 value of 57,28 ppm so that purnajiwa extract has strong antioxidant activity that could be used as natural antioxidant resources.

A Study of the Mechanisms of Guaiacol Pyrolysis Based on Free Radicals Detection Technology

In order to understand the reaction mechanism of lignin pyrolysis, the pyrolysis process of guaiacol (o-methoxyphenol) as a lignin model compound was studied by free radical detection technology (electron paramagnetic resonance, EPR) in this paper. It was proven that the pyrolysis reaction of guaiacol is a free radical reaction, and the free radicals which can be detected mainly by EPR are methyl radicals. This paper proposes a process in which four free radicals (radicals 1- C6H4(OH)O*, radicals 5- C6H4(OCH3)O*, methyl radicals, and hydrogen radicals) are continuously rearranged during the pyrolysis of guaiacol.