Costel Moldoveanu

Synthesis and antituberculosis activity of some new pyridazine derivatives. Part II.

A series of eighteen novel compounds with pyridazine moiety were synthesized and their in vitro antituberculosis activities have been evaluated. A fast, general, and facile method for preparation of pyridazine derivatives in moderate to excellent yields is presented. Three compounds were found to be moderate active against Mycobacterium tuberculosis. Correlation of structure-biological activity has been done.

Diazinium salts with dihydroxyacetophenone skeleton: Syntheses and antimicrobial activity.

Herein we report a feasible study concerning syntheses, structure and antimicrobial activity of some new diazinium salts with dihydroxyacetophenone skeleton. A fast, general, environmentally friendly, and facile method for preparation of diazinium salts under microwave and ultrasounds irradiation is presented. Antimicrobial tests prove that some diazine compounds have a remarkable activity against different microorganisms (germs and fungi), the pyrimidine derivatives being more active. Correlations between structure and antimicrobial activity are reported.

A facile synthesis of pyridazinone derivatives under ultrasonic irradiation.

A new, efficient and general method for preparation of N-substituted-pyridazinones using ultrasound irradiation is reported. Under ultrasound the reaction time decreases substantially, the yields are high and the reaction conditions are mild. It was noticed that substituents at the 3-(6)-position of pyridazone heterocycle have a substantial influence on the reactivity, while the effect of the substituents at the 1-(2)-position seems to be of minor importance. A comparative study of the reactions performed under ultrasound conditions versus at room temperature has been done.

Ultrasound assisted reactions of steroid analogous of anticipated biological activities.

A new, fast, efficient and general method for preparation of steroid analogous of anticipated biological activity under ultrasound irradiation and classical heating is reported. The reaction pathway involves two steps: quaternization of phthalazine heterocycle followed by a 3+2 dipolar cycloaddition of cycloimmonium ylides to dienophiles. Under ultrasound the reaction time decreases substantially, the yields are higher, the reaction conditions are milder. A comparative study ultrasound verses classical heating has been done.

Microwave Assisted Reactions of Some Azaheterocylic Compounds

A fast, general, environmentally friendly and facile method for preparation of five- and six-membered ring diazaheterocylic salts under microwave irradiation is presented. The N-alkylation reactions of imidazole, pyrimidine, pyridazine and phthalazine have been studied. The microwaves remarkably accelerated these N-alkylations, the reaction times decreased dramatically, the reaction conditions were milder, the consumed energy decreased considerably and the amount of solvents used was reduced substantially. Consequently, the microwave assisted alkylation of N-containing heterocycles could be considered eco-friendly. In some cases, under MW irradiation the yields are also higher. A comparative study of microwave vs. classical conditions (liquid solvents) has been done. Twelve new diazaheterocylic salts of potential practical interest were obtained.

Hybrid imidazole (benzimidazole)/pyridine (quinoline) derivatives and evaluation of their anticancer and antimycobacterial activity

Abstract The design, synthesis, structure, and in vitro anticancer and antimycobacterial activity of new hybrid imidazole (benzimidazole)/pyridine (quinoline) derivatives are described. The strategy adopted for synthesis is straight and efficient, involving a three-step setup procedure: N-acylation, N-alkylation, and quaternization of nitrogen heterocycle. The solubility in microbiological medium and anticancer and antimycobacterial activity of a selection of new synthesized compounds were evaluated. The hybrid derivatives have an excellent solubility in microbiological medium, which make them promising from the pharmacological properties point of view. One of the hybrid compounds, 9 (with a benzimidazole and 8-aminoquinoline skeleton), exhibits a very good and selective antitumor activity against Renal Cancer A498 and Breast Cancer MDA-MB-468. Moreover, the anticancer assay suggests that the hybrid Imz (Bimz)/2-AP (8-AQ) compounds present a specific affinity to Renal Cancer A498. Concerning the antimycobacterial activity, only the hybrid compound, 9, has a significant activity. SAR correlations have been performed.

A New Pathway for the Synthesis of a New Class of Blue Fluorescent Benzofuran Derivatives

In this study an efficient and straightforward method for obtaining a new class of blue fluorescent bezofuran derivatives, under microwave irradiation, as well as under conventional thermal heating, is presented. Under conventional TH the reactions occur selectively, and a single type of benzofuran ester derivative was obtained. The synthesis under MW irradiation also led to benzofuran derivatives, but in a time-dependent manner. Irradiation for a short period of time led to a mixture of two types of benzofuran derivatives (3a–c and 4a–c), while MW irradiation for a longer period of time led to a single type of benzofuran (3-methylbenzofuran), the reaction becoming highly selective. Taking into consideration the advantages offered by MW irradiation in terms of a substantial decrease of solvent consumed, a substantial reduction in reaction time (from days to hours), and a consequent diminution in energy consumption, these methods could be considered environmentally friendly. Here, feasible reaction mechanisms for the benzofuran derivatives formation are described. The absorption and fluorescence emission of the obtained benzofuran derivatives were studied, with part of these compounds being intense blue emitters. A certain influence of the benzofuran substituents concerning absorption and fluorescent properties was observed. Only compounds anchored with a carbomethoxy group of furan ring have shown good quantum yields.

The Cycloaddition of the Benzimidazolium Ylides with Alkynes: New Mechanistic Insights.

New insights concerning the reaction mechanism in the cycloaddition reaction of benzimidazolium ylides to activated alkynes are presented. The proposed pathway leading both to 2-(1H-pyrrol-1-yl)anilines and to pyrrolo[1,2-a]quinoxalin-4(5H)-ones involves an opening of the imidazole ring from the cycloaddition product, followed by a nucleophilic attack of the aminic nitrogen to a proximal carbonyl group and the elimination of a leaving group. The mechanistic considerations are fully supported by experimental data, including the XRD resolved structure of the key reaction intermediate.

Problem solving - an interactive active method for teaching the thermokinetic concept

Abstract The paper describes a strategy that uses problem solving to teach the thermokinetic concept, based on student’s previously established proficiency in thermochemistry and kinetics. Chemistry teachers often use this method because it ensures easy achievement of both formative and informative science skills. This teaching strategy is tailored for students that prove special intellectual resources, Olympiad participants and to those who find chemistry a potential professional route

Study on the thermal behavior of casein in air

Abstract The present paper is focused on the study of the thermal behavior of casein, the main protein in milk, by applying the TG-FTIR technique and calorimetric measurements. The research is of a great interest due to the large application areas of casein in cosmetic, food and pharmaceutical industries. The analysis of the thermal behavior by the TG-DTG-DTA methods allwos the finding of the temperature range where the casein is thermally stable and the caseincontaining cosmetics, food and pharmaceutical products proper for using. The identification of the gaseous species released allwos the TG-FTIR coupled technique to give useful information on the possible environmental impact when the casein-containing products are used at temperatures above the casein initial degradation temperature. The combustion heat of casein estimated by means of the Berthelot calorimeter made evident this value to be close to those of the most important and used fuels which would recommend the waste casein-containing products to be used as fuels.