Green solvents in organoselenium chemistry

© 2018, Springer Nature Switzerland AG. Organoselenium chemistry involves unique methods for the preparation of reaction intermediates and biologically relevant compounds. However, common methods frequently have drawbacks such as the use of halogenated volatile solvents, expensive catalysts systems and sophisticated experimental fittings. Therefore, sustainable organoselenium chemistry is developing. Here, we review green solvent alternatives in organoselenium chemistry. We present the application of the ionic liquids and deep eutectic solvents in the synthesis of seleno-functionalized molecules under mild reaction conditions; the application of polyethylene glycol, glycerol and ethanol as solvents; and the use of organoselenium compounds as starting materials for the preparation of ionic liquids

Kinetic Study of the Pyridine-Catalyzed Selenolactonization of 4-Pentenoic Acid

© 2020, Springer Science+Business Media, LLC, part of Springer Nature. Abstract: The kinetics and mechanism of the pyridine-catalyzed cyclofunctionalization of 4-pentenoic acid by means of PhSeX (X = Cl, Br) have been investigated spectrophotometrically, under pseudo-first order reaction conditions. The influence of the reaction temperature, the type of cyclization reagent and used catalyst on the reaction rate and mechanism was examined. The obtained data have showed that rate constants go on increasing as the temperatures go up and with use of PhSeCl as reagent. Also, the reaction rate is directly depended on the type of the catalyst used—stronger bases with higher tendency for hydrogen bond formation (DN) are promoting reaction in more efficient way. Graphic Abstract: [Figure not available: see fulltext.]

STRESS, ADAPTATION AND THE POSSIBLE EFFECT OF PHYSICAL EXERCISE

All the categories of body feedback to stress arise from the disbalance between the stressor, on one hand, and the body resources available in overcoming stress on the other. If psychological stability is not at an optimal level, it causes the body homeostasis disbalance, physiological stability is damaged which leads to psychosomatic signs and diseases as the result of stress. As the key organ in overcoming stress, the brain has a significant role in adaptation to stress. That is why the scientists stress its potential and ability to regenerate and to provide the body with the potential to overcome the consequences of stress. In order to prevent and reduce the consequences of the influence of the stressogenic stimuli on the body, the way man can improve his quality of life and body health should be taken into account. Physical activity is one of the ways of achieving that goal, and the fact regarding the positive influence of physical exercise on the health and the emotional status of the body is well known and has been confirmed scientifically in many medical and psychological studies. The aim of the paper is the influence of the analysis which stress can have on the brain and the body and the synthesis of the results which confirm the importance of physical activity in everyday life, and especially under post stress circumstances, that is, while adapting to stress. The effects of physical exercise, as a measure of prevention, influence the optimal health status of an individual, which indirectly improves the function and the efficacy of exercising. Advances in neuroscience have tasked experts with using their knowledge and findings about the positive influence of physical exercise in order to better understand all the aspects of adaptation to stress and the reestablishment of the body homeostasis

The influence of cobalt(II) and tin(II) chloride on regioselectivity and kinetics of phenylselenocyclization of 6-methyl-hept-5-en-2-ol

© 2019, Springer-Verlag GmbH Germany, part of Springer Nature. The reaction of the Δ4-alkenols with PhSeX can follow three possible reaction pathways: two pathways lead to the formation of two regioisomeric cyclic ether products through the process of intramolecular cyclization, while the third represents the addition of the reagent to the double bond of an alkenol. As there are relatively few literature data on the kinetics of these reactions, we have chosen 6-methyl-hept-5-en-2-ol as a substrate of interest in order to obtain valuable results that will enable better understanding of the mechanism of phenylselenoetherification reactions. 6-Methyl-hept-5-en-2-ol is a particularly interesting model-substrate due to its substitution pattern of functional groups involved in the cyclization process. In this research, through synthetic and kinetic studies, we aimed to resolve key questions concerning the influence on kinetics, chemo- and regioselectivity of the reagent’s counter ion, steric hindrances in substrate functional groups and the presence of additives

An introduction to the kinetics of the triethylamine-mediated selenocyclofunctionalization of 4-pentenoic acid

© 2018 Elsevier B.V. The aim of this work is exploration of kinetic, thermodynamic and mechanistic aspects of triethylamine-mediated selenocyclofunctionalization of 4-pentenoic acid by means of phenylselenyl halides (PhSeCl and PhSeBr). The kinetics and mechanism for these reactions have been investigated by the UV–Vis spectrophotometry. The rate constants, as well as thermodynamic parameters (ΔH≠, ΔS≠) have been determined using UV–Vis method at three different temperatures (288, 298 and 308 K) in THF as a solvent. All studied reactions gave negative values for entropy of activation, which is in agreement with the SN2 mechanism of substitution. In addition, obtained values for the rate constants have indicated the higher reactivity of PhSeCl as reagent for cyclization

Cost-effectiveness analysis of tocilizumab in combination with methotrexate for rheumatoid arthritis: A Markov model based on data from Serbia, country in socioeconomic transition

Background/Aim. Recent studies have shown that biological treatments for rheumatoid arthritis can change the course of rheumatoid arthritis and improve functional ability of patients with rheumatoid arthritis. In spite of this fact, use of biological therapy is still limited by high prices of these medicines, especially in countries in socioeconomic transition. The aim of our study was to compare costeffectiveness of a combination of tocilizumab and methotrexate with methotrexate alone for rheumatoid arthritis in Serbia, a country in socioeconomic transition. Methods. For the purpose of our study we designed a Markov model using data on therapy efficacy from the available literature, and data on the costs of health states calculated from records of actual patients treated in the Clinical Center Kragujevac, Serbia. The duration of one cycle in our model was set at one month, and the time horizon was 480 months (40 years). The study was done from the social perspective, and all the costs and outcomes were discounted for 3% per year. Results. Treating rheumatoid arthritis with diseasemodifying antirheumatic drugs (DMARDs) alone was more cost-effective in comparison with a combination of biologic treatment with tocilizumab and DMARDs. The total costs for treating a patient with DMARDs for one year were on average 261,945.42 RSD, or 2,497.70 Euro and the total costs for treatment with tocilizimab plus DMARDs were on average 1,959,217.44 RSD, or 18,659.20 Euro. However, these results are susceptible to changes in costs and treatment effects of tocilizumab in patients with more severe forms of rheumatoid arthritis. Conclusion. Our results show that the use of tocilizumab for rheumatoid arthrits in economic environment of Serbia is not cost-effective. Use of tocilizumab for treating rheumatoid arthritis can become affordable, if costs of its use become lower. In order to start using expensive biologic medicines in patients in transitional countries, special strategy and pricing policy of international pharmaceutical companies are necessary, which would include calculation of prices of biologic medicines on the basis of local pharmacoeconomic studies

Inflammatory Bowel Diseases (Crohn's Disease and Ulcerative Colitis): Cost of Treatment in Serbia and the Implications

BACKGROUND: Although the costs of treating inflammatory bowel disease (IBD) in developed countries are well established, they remain largely unknown in countries with recent histories of socio-economic transition including Serbia. OBJECTIVE: To estimate the costs of treatment including the resources used by patients with IBD in Serbia from a societal perspective. This includes both Crohn's disease and ulcerative colitis. METHODS: This cost-of-illness study was conducted to identify direct, indirect and out-of-pocket costs of treating patients with IBD in Serbia. Patients with IBD (n = 112) completed a semi-structured questionnaire with data concerning their utilisation of heath-care resources and illness-related expenditures. All costs were calculated in Republic of Serbia dinars (RSD) at a 1-year level (2014) and subsequently converted to Euros. Median values and ranges were reported to avoid potential distortions associated with mean costs. RESULTS: Median total direct costs and total indirect costs per patient per year in patients with Crohn's disease were 192,614.32RSD (€1602.97) and 28,014.00RSD (€233.13) and 142,267.15RSD (€1183.97) and 21,436.00RSD (€178.39), respectively, in patients with ulcerative colitis. In both groups, the greatest component of direct costs was hospitalisation. CONCLUSIONS: Costs of IBD in Serbia are lower than in more developed countries for two reasons. These include the fact that expensive biological therapy is currently under-utilised in Serbia and prices of health services are largely controlled by the State at a low level. The under-utilisation of biologicals may change with the advent of biosimilars at increasingly lower prices

Synthesis of Racemic 2-(Aminomethyl)cyclopropane-1,1-dicarboxylic Acid as a New Constrained γ-Amino Dicarboxylic Acid Bypassing Alkyl 3-Aza-2-oxobicyclo[3.1.0]hexane-1-carboxylates

© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim The first synthesis of racemic 2-(aminomethyl)cyclopropane-1,1-dicarboxylic acid was developed involving sequential iodocarbocyclization, azidation, saponification and reduction of dimethyl 2-allylmalonate. The developed synthetic pathway avoids reactions such as ring opening of the cyclopropane ring toward acyclic δ-amino carboxylic acid derivatives or lactamisation toward bicyclic methyl 3-aza-2-oxobicyclo[3.1.0]hexane-1-carboxylates which occur in alternative synthetic strategies

Dynamics of multivalued linear operators

[EN] We introduce several notions of linear dynamics for multivalued linear operators (MLO¿s) between separable Fréchet spaces, such as hypercyclicity, topological transitivity, topologically mixing property, and Devaney chaos. We also consider the case of disjointness, in which any of these properties are simultaneously satisfied by several operators. We revisit some sufficient well-known computable criteria for determining those properties. The analysis of the dynamics of extensions of linear operators to MLO¿s is also considered.The second and fourth authors have been supported by MINECO and FEDER, grant MTM2016-75963-P.Chen, C.; Conejero, JA.; Kostic, M.; Murillo Arcila, M. (2017). Dynamics of multivalued linear operators. Open Mathematics. 15:948-958. https://doi.org/10.1515/math-2017-0082S9489581

AMBIENT TEACHING – LEARNING ENVIRONMENT FOR GIFTED STUDENTS IN CHEMISTRY

Establishing a learning environment for gifted students is of great importance since it should encompass the development of their interpersonal skills, social responsibility and enable effective delivery of teaching instructions (Miedijensky, 2018). Contrary to traditional school learning through the adoption of final products of scientific research, ambient teaching is offering high degree of adoption of a scientific way of thinking and engagement of students, starting from observational procedures, to extracting and collection of materials (Lehrer, & Schauble, 2006). Our study aimed to explore the gifted students’ perceptions regarding the ambient teaching as a model for learning environment. 24 gifted students from elementary schools in Kragujevac attended at the workshop in the laboratory at the Faculty of Science. The workshop was dedicated to the basic principles and laboratory operations and equipment, while problems were carefully designed to meet the cognitive needs of gifted students. Interview was used as instrument for delineation of the gifted students’ perceptions regarding the ambient teaching. According to the results, majority of the students confirmed the significance and suitability of the ambient teaching for the learning chemistry as school subject, as well as they considered this way of learning more interesting than traditional method used in schools.Publishe