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Synthesis and reactivity of hypervalent sulfur fluorides
Ajenjo, Javier ; Beier, Petr (advisor) ; Jahn, Ullrich (referee) ; Cibulka, Radek (referee)
The pentafluorosulfanyl (SF5) group displays remarkable and unique properties, including large dipole moment, high electronegativity, high thermal and chemical stability, as well as high lipophilicity. However, only a few synthetic methods for the preparation of aromatic pentafluorosulfanyl building blocks have been developed to date. This work aims at improving availability and accessibility of aryl sulfurpentafluoride building blocks. In the first part of the work, the synthesis of aryl sulfurpentafluorides by the direct fluorination of diaryl disulfides with elemental fluorine is described. Nowadays, this synthetic strategy is used by industry on a multi-kilogram scale. However, the scope of the reaction is only limited to 3- and 4- nitro-1-(pentafluorosulfanyl)benzenes. In this work, the synthesis of various para-, meta- and ortho-substituted-(pentafluorosulfanyl)benzenes following the same approach was carried out. In the second part, the derivatization of aryl sulfurpentafluoride building blocks was investigated. Direct fluorination of 3-nitro-1-(pentafluorosulfanyl)benzene afforded 3-fluoro-5-nitro-1- (pentafluorosulfanyl)benzene. The titled compound was derivatized by two different processes: nucleophilic aromatic substitution (SNAr) of fluorine and vicarious nucleophilic substitution of...
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Reactivity of transition metals - influence of the degree of oxidation of active substrate
Kettner, Miroslav ; Nehasil, Václav (advisor)
The impacts of fluorine doping of ceria are studied by means of surface science experimental methods. Fluorine-doped and fluorine-free ceria layers are epitaxially grown on rhodium single crystals and their properties are compared in regular and inverse catalyst configurations. A procedure for epitaxial growth of CeO2(110) and CeOxFy(110) layers on Rh(110) single crystal is developed and described in detail. Shape alterations of Ce 3d spectrum brought about by fluorine doping are explained and a suitable deconvolution method is proposed. Special attention is focused towards stability of fluorine in ceria. Presented data show that fluorine incorporation in ceria lattice causes stable reduction of ceria, which withstands up to 200řC in near-ambient pressure conditions. Morphological changes are observed due to elongation of surface lattice constant of reduced ceria. Oxygen storage capacities and hydrogen oxidation reaction rates of four different studied systems are compared and discussed. The twofold nature of oxygen exposure of fluorinated ceria is discovered and explained. Oxygen repels fluorine from the surface, while the remaining part of fluorine is expelled to adsorbate positions, where its electronic state is altered. Moreover, such fluorine is prone to interact with atomic hydrogen. This reaction is...
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Fluorine nuclear relaxation times in chelates with lanthanides
Bobrova, Yulia ; Římal, Václav (advisor) ; Wagnerová, Dita (referee)
Contrast agents containing fluorine have great prospects for magnetic resonance imaging in medicine. Low representation of fluorine in human body and the suitable magnetic properties of its nucleus 19 F, provide great sensitivity. The slow relaxation of 19 F, can be shortened by using paramagnetic complexes.In this thesis, transversal and longitudinal 19 F relaxation times of chelates with different paramagnetic lanthanides (Ce, Yb,Tm, Dy, Ho) were measured in two different magnetic fields: 4,7 and 11,7 T. Their values meet the expected assumptions. Furthermore, the values are compared with Bloch-Redfield- Wangsness theory.While Ho, Tm, and Dy reduce fluorine nuclear relaxation times to milliseconds, which is too short for MRI, relaxation rates of Ce a Yb reach approximately 100ms. Such relaxation rates can be considered as optimal for imaging methods. On the basis of our results it is possible to find suitable candidates for fluorine contrast media and optimize the measurement sequence settings in further research or in clinical use.
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Reactivity of transition metals - influence of the degree of oxidation of active substrate
Kettner, Miroslav ; Nehasil, Václav (advisor) ; Jiříček, Petr (referee) ; Lykhach, Yaroslava (referee)
The impacts of fluorine doping of ceria are studied by means of surface science experimental methods. Fluorine-doped and fluorine-free ceria layers are epitaxially grown on rhodium single crystals and their properties are compared in regular and inverse catalyst configurations. A procedure for epitaxial growth of CeO2(110) and CeOxFy(110) layers on Rh(110) single crystal is developed and described in detail. Shape alterations of Ce 3d spectrum brought about by fluorine doping are explained and a suitable deconvolution method is proposed. Special attention is focused towards stability of fluorine in ceria. Presented data show that fluorine incorporation in ceria lattice causes stable reduction of ceria, which withstands up to 200řC in near-ambient pressure conditions. Morphological changes are observed due to elongation of surface lattice constant of reduced ceria. Oxygen storage capacities and hydrogen oxidation reaction rates of four different studied systems are compared and discussed. The twofold nature of oxygen exposure of fluorinated ceria is discovered and explained. Oxygen repels fluorine from the surface, while the remaining part of fluorine is expelled to adsorbate positions, where its electronic state is altered. Moreover, such fluorine is prone to interact with atomic hydrogen. This reaction is...
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Sulfur-based reagents for nucleophilic and radical introduction of tetrafluoroethyl and tetrafluoroethylene groups
Chernykh, Yana ; Beier, Petr (advisor) ; Kvíčala, Jaroslav (referee) ; Církva, Vladimír (referee)
Charles University in Prague, Faculty of Science Department of Organic Chemistry Ing. Yana Chernykh Sulfur-Based Reagents for Nucleophilic and Radical Introduction of Tetrafluoroethyl and Tetrafluoroethylene Groups Ph.D. Thesis Prague 2014 ABSTRACT This project was aimed at developing new methodologies for selective introduction of tetrafluoroethyl and tetrafluoroethylene groups into organic molecules. The study was focused on reactivities of fluorinated sulfones and sulfides as tetrafluoroalkylation reagents. In the Introduction part of the thesis, main aspects of organofluorine chemistry are outlined, illustrating beneficial effects of fluorine atoms on physical, chemical and biological properties of organic compounds. General synthetic methods for the selective introduction of fluorine atoms and fluoroalkyl groups to organic molecules are described. Particular attention is given to reactivity and applications of CF2CF2-containing compounds, indicating challenges in synthetic approaches toward tetrafluoroalkylation. The Results and discussion part describes reactivities of four new fluorinated organosulfur reagents as tetrafluoroethyl and tetrafluoroethylene building blocks. The application of these reagents as various carbanionic or radical synthons proved to be effective for the incorporation of CF2CF2...
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Nucleophilic introduction of fluorinated functional groups using organophosphorus compounds.
Opekar, Stanislav ; Beier, Petr (advisor) ; Veselý, Jan (referee) ; Kvíčala, Jaroslav (referee)
In the Introduction part of this thesis, the chemistry of organofluorine compounds is discussed, particularly the methods for the preparation of organofluorine compounds mainly by fluoroalkylation methods. Furthermore, the chemistry of fluorinated phosphonates, methods of their preparation, reactivity and biological activity is discussed. Additionally, the reactivity of fluoromethane derivatives is briefly mentioned and especially, the reactivity of diethyl fluoromalonate and fluorobisfenylsulfonylmethane is described. The Results and discussion part is devoted to the reactivity of three fluorinated phosphonates: tetraethyl fluoromethylenbisphosphonate, diethyl fluorophenylsulfonylphosphonate and previously not described diethyl fluoronitromethylphosphonate. These fluorinated phosphonates belong to the family of nucleophilic monofluoroalkylation reagents, meaning that these compounds are convenient starting materials for the synthesis of complex organic molecules containing the fluorine atom. The results deal with the reactivity of above mentioned fluorinated phosphonates, mainly with alkylation reactions, Horner-Wadsworth-Emmons reactions and conjugated additions. Also, other synthetic methods such as the Mitsunobu reaction or the palladium catalyzed allylation reaction were investigated; however,...
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Printed transparent oxide conductors
Bartoš, Radim ; Pekárková, Jana (referee) ; Dzik, Petr (advisor)
Thin films of tin oxide doped by fluorine or antimony were prepared by spincoating technique and material printing technique. Plenty of inorganic and organic coumpouds were used as precursors of fluorine and antimony. Sheet resistence of films were measured by 4-probe method and film thickness were determined by contact profilometer. Films were analyzed by Xray diffraction (XRD) and scan electron microscopy (SEM).
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Hygiene and care of the external genital in peditaric gynecology.
TUČKOVÁ, Martina
This Bachelor Dissertation's theme is the care and hygiene of a female child's outer genitals. It focuses on finding out the level of mothers' information on the subject. Different stages of girls' age and development are examined from a gynaecological point of view; anatomical differences are described in the theoretical part of the work. Hygienic care of the outer genital is closely associated with incidence of gynaecological illness during childhood, vulvovaginitis and development of synechiae, and further chapters are devoted to explanation of these terms. The role of a midwife, education and communication with the young female patient, her parents and especially with her mother arethe integral part of the practical work. Experimental section was carried out by a quantitative method via an anonymous non-standardised questionnaire aimed at mothers of girls aged from birth to 12 years. The questionnaires were handed out in Prague during February and March 2014 at two selected gynaecological ambulances, one medical centre for children and a maternity department of a university hospital. The main aim of this work was to find the level of knowledge mothers had about hygiene and care of a girl's outer genital. Two questions were asked. The first one sought to find out how mothers gain knowledge and information about the care for a girl's outer genital and second one aimed to find out how the genital care is carried out. From the analysis of these findings it was ascertained that from 94 respondents the largest group had university level education, 31-35 years old caring for one daughter aged 25 months to six years old. It was also found that a great majority of these mothers had generally correct information about hygienic care of girl's outer genital and it can be presumed they were well equipped to carry it out by methods recommended in the specialist literature. All mothers knew the correct way of cleaning a girl's bottom following defecation and majority used running water. Nevertheless, the area mothers are not so certain about is synechiae and its prevention. Although the question about care of a girl's outer genital up to 2 years of age was generally answered correctly, it was shown from further responses that 37 % did not know whether the hygienic care can affect development of synechiae. It also transpired that mothers not only gain the appropriate information from their children's practical doctors but also from internet. Should their daughters have any gynaecological problems, these mothers would seek help from a specialist child gynaecologist. It was also found that the appropriate instructions were given to mothers in the hospital by a midwife or child nurse. The midwife was only minimally involved in educating mothers about care and hygiene for their baby daughters. The number of mothers requesting further information about care and hygiene was practically equal to the number of respondents that have already stated that they are sufficiently informed already. From that follows that although most mothers are sufficiently well informed, there is a room for improvement by further widening of information about problems of synechiae. Although mothers are in majority sufficiently informed about the care of the outer genitals, there is, however, in specialist medical literature prevailing opinion that bacterial infection is the cause of vulvovaginitis. In conclusion are the recommendations for further use of this work. It is recommended as a source of information for midwifes, specialist and general nurses involved in education mothers of girls of all ages. It was also recommended to create a specialist leaflet that would highlight the important information mothers need to provide an appropriate care for a girl's outer genitalia.
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