Simple synthesis of pyrrolo[3,2-e]indole-1-carbonitriles

Alkylation of 5-nitroindol-4-ylacetonitriles with ethyl chloroacetate, α-halomethyl ketones, and chloroacetonitrile followed by a treatment of the products with chlorotrimethylsilane in the presence of DBU gives 1-cyanopyrrolo[3,2-e]indoles substituted in position 2 with electron-withdrawing groups

Nitro-Substituted Hoveyda-Grubbs Ruthenium Carbenes: Enhancement of Catalyst Activity through Electronic Activation

The design, synthesis, stability, and catalytic activity of nitro-substituted Hoveyda-Grubbs metathesis catalysts are described. The highly active and stable meta- and para-substituted complexes are attractive from a practical point of view. These catalysts operate in very mild conditions and can be successfully applied in various types of metathesis [ring-closing metathesis, cross-metathesis (CM), and enyne metathesis]. Although the presence of a NO2 group leads to catalysts that are dramatically more active than both the second-generation Grubbs’s catalyst and the phosphine-free Hoveyda’s carbene, enhancement of reactivity is somewhat lower than that observed for a sterically activated Hoveyda-Grubbs catalyst. Attempts to combine two modes of activation, steric and electronic, result in severely decreasing a catalyst’s stability. The present findings illustrate that different Ru catalysts turned out to be optimal for different applications. Whereas phosphine-free carbenes are catalysts of choice for CM of various electron-deficient substrates, they exhibit lower reactivity in the formation of tetrasubstituted double bonds. This demonstrates that no single catalyst outperforms all others in all possible applications.

Possibilities of Integrating Adsorption Chiller with Solar Collectors for Polish Climate Zone

Solar-powered adsorption chillers are a particularly interesting alternative to energy-intensive conventional refrigeration systems. Integration of the adsorption chiller with solar collectors is a very promising concept since the increase in solar radiation coincides with the increased demand for cooling. Such a solution is very economical and environmentally friendly. It also fits in with current trends related to energy policy and sustainable development. The article presents the results of tests conducted for a two-bed adsorption chiller integrated with solar collectors. The tests were performed on selected days of the summer period (July and August) at the KEZO Research Centre PAS in Jablonna (Poland). Based on the results obtained, the performance parameters of the adsorption chiller were determined, and the problems associated with the integration of all components of the system were identified and discussed. The values of the determined Coefficient of Performance (COP) and cooling capacity for the tested adsorption chiller are, depending on the day on which the tests were conducted, from 0.531 to 0.692 and from 5.16 kW to 8.71 kW, respectively. Analysis of the test results made it possible to formulate conclusions related to the design of integrated systems of adsorption chillers with solar collectors

Possibilities of Integrating Adsorption Chiller with Solar Collectors for Polish Climate Zone

Solar-powered adsorption chillers are a particularly interesting alternative to energy-intensive conventional refrigeration systems. Integration of the adsorption chiller with solar collectors is a very promising concept since the increase in solar radiation coincides with the increased demand for cooling. Such a solution is very economical and environmentally friendly. It also fits in with current trends related to energy policy and sustainable development. The article presents the results of tests conducted for a two-bed adsorption chiller integrated with solar collectors. The tests were performed on selected days of the summer period (July and August) at the KEZO Research Centre PAS in Jablonna (Poland). Based on the results obtained, the performance parameters of the adsorption chiller were determined, and the problems associated with the integration of all components of the system were identified and discussed. The values of the determined Coefficient of Performance (COP) and cooling capacity for the tested adsorption chiller are, depending on the day on which the tests were conducted, from 0.531 to 0.692 and from 5.16 kW to 8.71 kW, respectively. Analysis of the test results made it possible to formulate conclusions related to the design of integrated systems of adsorption chillers with solar collectors

Ways of increasing natural gas storage capacity in underground gas storages in the Czech Republic

Natural gas fields are usually located far away from the end users and industrially developed countries, where the gas demand is highest. In such cases, natural gas is transported from the production site to the receiver mainly with gas pipelines. Such pipelines may transmit a definite volume of natural gas. Most of the time gas transport is stable in time, unless the demand changes, e.g. in winter or in the case of pipeline failure. In such a case the pipeline system cannot cover the increased demand and supply sufficient amounts of gas. One of the ways to solve the problem of varying demand and limited potential as far as gas transmission over long distances is concerned, are underground gas storages, thanks to which the operational gas deliveries can be regulated, i.e. it can be stored in periods of lower demand and used in the high demand situations. This safety buffer provides the stability and reliability of the entire natural gas distribution system. The methods of increasing the natural gas storage capacity of UGS were discussed in this paper with special emphasis on the primary and secondary tightness of geological structures hosting UGS. Authors also analyzed how laboratory tests conducted at VŠB-TU Ostrava can be broadened to verify the possibilities of increasing natural gas storing capacity, depending of the geological horizons and structures in which the UGS is located