Steric and Polar Factors Affecting Heteroring Opening of 2-[2-carboxy-3,4,5,6-tetrachloro]phenyl-4H-3,1-Benzoxazin-4-one by Nitrogen and Carbon Nucleophiles

The behavior of 2-[2-carboxy-3,4,5,6-tetrachloro]phenyl-4H-3,1-Benzoxazin-4-  one towards Nitrogen nucleophiles and Carbon nucleophiles under Friedel–Crafts' reaction conditions has been investigated and steric versus polar factors affecting ring opening has been studied

Facile synthesis of new fused and non-fused heterocyclic systems from a γ-ketoacid

The chemical reactivity of 4-(2-tetryl)-4-oxobut-2-enoic acid towards carbon, nitrogen, oxygen, sulfur nucleophiles and binucleophiles namely o-phenylenediamine, o-aminophenol, and o-aminothiophenol has been studied. The investigated nucleophilic reactions result in the formation of heterocyclic compounds with fused and non-fused systems namely, pyridazinone, tetrhydroquinoline, quinoxalone, oxazinone, thiazole and benzocoumarin

Antioksidativno djelovanje metanolnih ekstrakata listova sedam egipatskih vrsta roda Cassia

In the present study, antioxidant activity of methanolic extracts of the leaves of seven Egyptian Cassia species was investigated using two methods, the phosphomolybdate method and 1,1 diphenyl-2-picrylhydrazyl radical (DPPH•) scavenging activity method. The results revealed that C. glauca is the most potent species and that the activity of other plant species decreases in the following order C. grandis > C. nodosa > C. fistula > C. didymobtrya > C. occidentalis > C. sophera. Defatted methanolic extract of the most active plant C. glauca was subjected to fractionation process using different organic solvents such as CHCl3, EtOAc and BuOH. Antioxidant activities of these fractions were investigated and the results showed that ethyl acetate fraction possessed high activity. Total phenolic and flavonoid concentration of each plant extract were determined using the Folin-Ciocaltu reagent and aluminum chloride. Correlation between radical scavenging capacities of extracts and total phenolic concentration was observed.U radu je ispitano antioksidativno djelovanje metanolnih ekstrakata listova sedam egipatskih vrsta roda Cassia koristeći fosfomolibdatnu metodu i metodu vezanja slobodnih 1,1-difenil-2-pikrilhidrazil radikala (DPPH.). Rezultati pokazuju da C. glauca ima najveću aktivnost te da se djelovanje smanjuje sljedećim redom: C. grandis C. nodosa C. fistula C. didymobtrya C. occidentalis C. sophera. Odmašćeni metanolni ekstrakt najaktivnije biljke C. glauca frakcioniran je pomoću različitih organskih otapala kao što su CHCl3, EtOAc i BuOH. Ispitivanje antioksidativnog djelovanja pojedinih frakcija pokazuje da je etil-acetatna frakcija najaktivnija. Pomoću Folin-Ciocaltuovog reagensa i aluminijevog klorida određena je ukupna koncentracija fenola i flavonoida svakog pojedinog ekstrakta. Uočena je korelacija između sposobnosti hvatanja slobodnih radikala i ukupnog sadržaja fenola

Why Online Teaching in General and Mathematics in Particular?

Over the last decade, the question has been online versus face-to-face teaching. Having taught Mathematics online for the past few years, I have developed many effective techniques that I believe my colleagues will find very valuable. The presentation will demonstrate how to design appealing course modules, how to present the content material in multiple ways, how to use a variety of supports to the students, effective methods of professor-student communication, and how to conduct regular assessment to keep students on task. I will also discuss some of the pros and cons of online teaching, and present ways to address the drawbacks of online teaching. I will discuss how teaching Mathematics online can remove some of the obstacles that Mathematics learners experience during the traditional face-to-face teaching. I will present some statistics to show the increasing rate of teaching Mathematics online nationwide and all over the world