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5-Alkyl and 5,5-Dialkyl Meldrum’s Acids
No full text5-Alkyl and 5,5-dialkyl Meldrum’s acids (1 and 2, respectively) are used in total synthesis.[1] Monoalkylated derivatives 1 are synthesized from Meldrum’s acid 3 by condensation with aldehyde[2] (or by acylation[3]) followed by hydrogenation.
5,5-Dialkyl Meldrum’s acids 2 can be obtained by alkylation of Meldrum’s acid 3 or its monoalkylated derivatives 1 (Scheme [1]).[4] Herein, reactions of Meldrum’s acids 1 and 2 proceeding with destruction of 1,3-dioxane cycle are reviewed
Bioaugmentation to Improve Biogas Yield in Cheese Whey Anaerobic Digestion
No full textIn this study bioaugmentation using two monocultures was investigated, namely Methanosarcina barkeri and Methanococcus vanniellii. The volatile fatty acid concentration was lower compared to the non-bioaugmented reference which indicates faster nutrient degradation by bioaugmented experiments. The changes between the two cultures were minimal; however it was evident that Methanosarcina barkeri when applied to cheese whey produced biogas with increased rate compared to Methanococcus vanniellii. A 20% increase of biogas yield was obtained for both cultures. Both cultures, according to the measurements of biogas, volatile fatty acids and total organic carbon indicated good potential to be applied for bioaugmentation of cheese whey
Structural Proof of Tetrazolo[1,5-A]Quinazoline Derivatives and Their Application in the Synthesis of 4-Amino-2-(1,2,3-Triazol-1-Yl)-Quinazolines
No full text5-Azidotetrazolo[1,5-a]quinazoline (formally known as 2,4-diazidoquinazoline) undergoes regioselective nucleophilic aromatic substitution with amines at C(5) and provides corresponding 5-amino derivatives of tetrazolo[1,5-a]quinazoline. For the first time the molecular structure of the latter tricyclic system is unambiguously proved by X-ray diffraction analysis. Tautomeric equilibrium between tetrazolo[1,5-a]quinazolines and 2-azido-quinazolines permits their use in the copper catalyzed azide-alkyne 1,3-dipolar cycloaddition reaction. In this way a series of N4-substituted derivatives of 4-amino-2-(1,2,3-triazol-1-yl)-quinazolines were obtained
Iodoacetic Acid is an Efficient Reagent for the Synthesis of Amino Acid Derived 1-Aminobenzimidazoles
No full textThe title compound is found to be the most efficient reagent to promote the cyclization—desulfurization of thioureas, derived from amino acid
Indirect C—H Azidation of Heterocycles via Copper-Catalyzed Regioselective Fragmentation of Unsymmetrical λ3-Iodanes
No full textA convenient approach to the synthesis of heteroaryl-substituted azides via C—H activation is followed by direct 1,3-dipolar Cu-catalyzed cycloaddition with terminal alkynes or by direct Cu-catalyzed reductive fragmentation to amino compounds
Drinking Water Disinfection with Electrolysis
No full textNowadays electrochemical disinfection has gained an increasing attention as an alternative to conventional drinking water disinfection, since it is regarded as environmentally friendly, amendable to automation, inexpensive, easily operated and is known to inactivate a wide variety of microorganisms from bacteria to viruses and algae. We found that along with increasing the number of electrodes in our equipment from 2 to 24, the resistance of chlorine-generating electrolytic cell and specific work of electric current decreased. During the electrolysis the amount of generated Cl2 increased along with the increase of chloride ion concentration in the solution and the intensity of electric current. The technological process parameters (flow rate, current intensity) have been established to obtain a predetermined amount of generated chlorine during the electrolysis process. A comparison of flow and circulating (3 times) regimes for electrolysis of tap water with chloride ion concentration below 10 mg/L showed that circulation is necessary to generate active chlorine (above 1 mg/L). At the same time, when no circulation was performed, even a 0.9 A treatment was not enough to generate detectable levels of free chlorine. Electrochemical disinfection of tap water with non-stoichiometric titanium oxide electrodes was effective enough to inactivate both metabolically active and cultivable bacteria E. coli to undetectable levels within 15 minutes at 0.5 A current intensity
Commercial and Prosthetic PMMA Surface Wettability Regulation
No full textThe subject of current research is modification of surface properties in nano scale with aim
to improve poly methyl metha acrylate performance for biomedical applications where interaction
between material and surrounding environment is critical, e.g. contact lenses, dental applications,
bone cement and many others
Solving Environmental Problems with Latvian Clay-Based Sorbents
No full textCurrently there is an increasing interest in application of natural clay minerals in production of various products, including sorbents for waste water treatment. For practical application of clay as a sorbent, it is significant not only to establish its properties, but also to be able to modify them. Only during the last twenty years, an increasing effort has been directed to systematic studies of clay sorption properties. A special attention has been devoted to improvement of clay sorption properties, which could allow to scientifically develop various sorbents for collection of oil products, such as oil spills from water surface, water processing and cleaning of waste waters from heavy metal ions, organic and inorganic admixtures, etc.
In this study, surface properties of Latvian Triassic (Vadakste deposit) smectite-containing clay samples were examined, in order to develop cheap, clay-based sorbents of high quality. Using sedimentation method, the granulometric composition of natural clay samples was determined. Surface morphology of the obtained samples was studied by using scan¬ning electron microscopy. Sorption properties of natural Vadakste deposit clay samples were modified by thermal treatment, as well as by adding a natural modifier based on hemicellulose and lignin (HLS). This type of clay modification has almost never been used in practice. Optimal thermal treatment conditions and HLS modification conditions were determined for the natural clay samples. It was found that water absorption decreased with increasing the thermal treatment temperature from 300 to 500 and 800 °C, however silicone oil and rapeseed oil absorption doubled at the same time. After adding HLS to clays within the range of 0.053% to 0.13%, both water and oil absorption doubled. The ability of natural and modified clay samples to adsorb copper and zinc ions from the corresponding salt solutions was investigated. The obtained results proved that the developed clay-based sorbent granules can be used for removal of copper and zinc ions from waste water, for collection of oil and oily substances; and as a cheap, environmentally safe pet litter
Optimal Polarization for Holographic Grating Readout in W-75 Azobenzene Molecular Glassy Film
No full textHolographic gratings (HG) in photosensitive materials are generally recorded by spatially modulated light intensity and light polarization distributions [1]. Thus the resulting HG is anisotropic and readout light polarization is important to achieve the maximum recording efficiency. In this paper, we have experimentally studied the effect of readout light polarization on the HG recording efficiency in a W-75 molecular glassy film and have found the optimal readout polarizations. No such studies are made until now, to our knowledg
