Search results for "Halogen"
showing 10 items of 434 documents
Synthesis of fluorinated oxadiazoles with gelation and oxygen storage ability
2012
A new family of fluorinated low molecular weight (LMW) gelators has been synthesized through SNAr substitution of 5-polyfluoroaryl-3-perfluoroheptyl-1,2,4-oxadiazoles with glycine ester. The obtained compounds give thermal and pH-sensitive hydrogels or thermo-reversible organogels in DMSO. Oxygen solubility studies showed the ability to maintain high oxygen levels in solution and in gel blend with plate counter agar (PCA).
Stereoselective Access to Fluorinated and Non-fluorinated Quaternary Piperidines: Synthesis of Pipecolic Acid and Iminosugar Derivatives
2012
The preparation of optically pure quaternary piperidines, both fluorinated and non-fluorinated, has been achieved from a chiral imino lactone derived from (R)-phenylglycinol. In the case of the fluorinated derivatives, the addition of (trifluoromethyl)trimethylsilane (TMSCF(3)) followed by iodoamination and migration of the CF(3) group allowed access to four derivatives of α-(trifluoromethyl)pipecolic acid. A theoretical study of the CF(3)-group rearrangement has been carried out to help establish the reaction mechanism of this uncommon transformation. Moreover, a route to trifluoromethyl-substituted iminosugars was also developed through the diastereoselective dihydroxylation of suitable s…
Plastifikatoru, halogenēto un fosfororganisko antipirēnu noteikšana mājas putekļos izmantojot masspetrometrijas metodes
2020
Plastifikatoru, halogenēto un fosfororganisko antipirēnu noteikšana mājas putekļos izmantojot masspektrometrijas metodes. Elīna Pasečnaja. Zinātniskais vadītājs Dr. ķīm. Dzintars Začs. Maģistra darbs, 57 lapas, 5 attēli, 15 tabulas, 67 literatūras avoti, 3 pielikumi. Darbs latviešu valodā. Maģistra darbā ir apkopota informācija par plastifikatoru, halogenēto un fosfororganisko antipirēnu savienojumiem, to īpašībām, izmantošanu, toksicitāti, izplatību apkārtējā vidē, kā arī ir apskatītas plastifikatoru un antipirēnu noteikšanas metodes. Eksperimentālajā daļā ir izstrādāta un validēta analītiskā metode plastifikatoru un antipirēnu noteikšanai putekļu paraugos, kura ir pielietota putekļu parau…
Halogenētu liesmas slāpētāju noteikšana bioloģiskās izcelsmes paraugos, izmantojot gāzu hromatogrāfiju – augstas izšķirtspējas masspektrometriju
2019
Maģistra darbā ir apkopota literatūra par halogenēto liesmas slāpētāju grupas savienojumiem, to īpašībām, izmantošanu, toksicitāti, izplatību apkārtējā vidē un noteikšanā izmantotajām analīzes metodēm. Literatūras apskatā ir pārskats par halogenēto liesmas slāpētāju izplatību putnu olās. Eksperimentālajā daļā ir izstrādāta un validēta halogenēto liesmas slāpētāju noteikšanas metode bioloģiskās izcelsmes paraugos, kura tika pielietota melnā stārķa (Ciconia nigra) olu paraugiem
Concerted halogen and hydrogen bonding in [RuI2(H2dcbpy)(CO)2]···I2···(CH3OH)···I2···[RuI2(H2dcbpy)(CO)2].
2011
A new type of concerted halogen bond-hydrogen bond interaction was found in the solid state structure of [RuI(2)(H(2)dcbpy)(CO)(2)]···I(2)···(MeOH)···I(2)···[RuI(2)(H(2)dcbpy)(CO)(2)]. The iodine atoms of the two I(2) molecules interact simultaneously with each other and with the OH group of methanol of crystallization. The interaction was characterized by single crystal X-ray measurements and by computational charge density analysis based on DFT calculations.
Synthesis of tetrahalide dianions directed by crystal engineering
2015
CrystEngComm 17(35), 6641-6645(2015). doi:10.1039/C5CE01288K
Iodinatedortho-Carboranes as Versatile Building Blocks to Design Intermolecular Interactions in Crystal Lattices
2009
[EN] The crystal structures of numerous iodinated ortho-carboranes have been studied, which has revealed the diversity of intermolecular interactions that these substances can adopt in the solid state. The nature-mostly as it relates to hydrogen and/or halogen bonds-and relative strength of such interactions can be adjusted by selectively introducing substituents onto the cluster, thus enabling the rational design of crystal lattices. In this work we present the newly determined crystal structures of the following iodinated ortho-carboranes: 9-I-1,2-closo-C2B10H11, 4,5,7,8,9,10,11,12-I-8-1,2-closo-C2B10H4, 3,4,5,6,7,8,9,10,11,12-I-10,-1,2-closo-C2B10H2, 1-Me-8,9,10,12-I-4-1,2-closo-C2B10H7,…
Systematic Construction of Ternary Cocrystals by Orthogonal and Robust Hydrogen and Halogen Bonds
2016
A carefully designed strategy is presented for the construction of ternary cocrystals, based on the orthogonality of two supramolecular interaction modes: hydrogen bonding between crown ethers and thioureas and the halogen bonding between thioureas and perfluorohalocarbons. Tested on a set comprising two crown ethers, two thioureas and five halogen bond donors, the strategy resulted in a high, 75% success rate, with 15/20 component combinations yielding at least one cocrystal. Crystal structure analysis revealed the interplay between the hydrogen and halogen bonding motifs, also shedding light on the variables affecting their formation. peerReviewed
Evaluation of the environmental impact of volcanic emissions from the chemistry of rainwater: Mount Etna area (Sicily)
2001
Abstract The S, halogen and NO 3 contents of rainwater samples from the Etnean area were studied in order to define the environmental impact of plume emissions on the local environment. Samples, collected on a network of 11 bulk rain gauges, show significant variability in anion content, which can be ascribed to different meteorological and environmental conditions at each sampling site and to a variable distance from the different source areas. Data analysis suggests that S, F, Cl and Br are mainly magma-derived, whereas NO 3 mainly originates from anthropogenic sources. Samples collected from sites close to craters display considerable temporal variability, with increased anion concentrat…
Two-Step Route to Indoles and Analogues from Haloarenes: A Variation on the Fischer Indole Synthesis
2012
In a new variation on the Fischer indole synthesis, readily available haloarenes are converted into a wide range of indoles in just two steps by halogen-magnesium exchange and quenching with di-tert-butyl azodicarboxylate, followed by reaction with aldehydes or ketones under acidic conditions. The protocol, which is readily extended to the preparation of indole isosteres, 4- and 6-azaindoles and thienopyrroles, obviates the need to prepare potentially toxic aryl hydrazines, simultaneously avoiding undesirable anilines such as naphthylamines.