Instytut Chemii Fizycznej i Teoretycznej; Kierunek: Informatyka Chemiczna
Institute of Physical and Theoretical Chemistry; Direction: Chemical Computer Science
Bibliogr. p. 159-166
Dissertations. Institute of Physical Chemistry PAS, 2001
Bibliogr. s. 159-166
Praca doktorska. Instytut Chemii Fizycznej PAN, 2001
U okviru ovog rada pripravljena su ukupno 73 nova liganda derivata trifenilfosfina s aminokiselinama, kraćim peptidima i/ili aminima. Ligandi su podijeljeni u tri skupine (A, B i C) obzirom na ...supstituciju fenilnog prstena fosfina i dentatnost, a njihovi in situ pripravljeni kompleksi s Rh(I) ispitani su kao homogeni katalizatori u reakcijama enantioselektivnog hidrogeniranja dvaju modelnih supstrata, metil-2-acetamidoprop-2-enoata (S1) i metil-(Z)-2-acetamido-3-fenilprop-2-enoata (S2). Kiralna informacija aminokiselina udaljena je od prokiralnog metala, a prenosi se "posrednom indukcijom" putem vodikovih veza. Postignuti maksimalni enantiomerni višak (ee) iznosi ee(R) = 68%, ee(S) = 84% i ee(R) = 81% upotrebom monodentatnih A, B, odnosno bidentatnih C liganda. Pripravljeni su Pd(II) i Pt(II) kompleksi s A i B u svrhu ispitivanja interakcija među ligandima. Priređeni ligandi i njihovi metalni kompleksi okarakterizirani su različitim analitičkim metodama (1H, 13C, 31P NMR, COSY, NOESY, ESI-MS, MALDI-TOF HRMS, CD i difrakcija X-zraka na jediničnom kristalu), a stereokemija produkata reakcije hidrogeniranja objašnjena je stereokemijskom analizom i DFT izračunima.
Within this thesis, a total of 73 new ligands based on triphenylphosphine derivatives with aminoacids, short peptides and/or amines, were synthesized. The ligands were divided into three categories (A, B, and C) by the phosphine phenyl ring substitution and denticity. Their in situ prepared Rh(I) complexes were tested as catalysts in the enantioselective hydrogenation of model substrates, methyl-2-acetamidoprop-2-enoate (S1) and methyl-(Z)-2-acetamido-3-phenylprop-2-enoate (S2). Chiral information from distant amino acids is transmitted to the prochiral metal through "backdoor induction" via hydrogen bonding. The obtained maximal enantiomeric excess (ee) is ee(R) = 68 %, ee(S) = 84 % and ee(R) = 81 % using monodentate A, B, and bidentate C ligands, respectively. Pd(II) and Pt(II) complexes of A and B were synthesized as model compounds for examination of ligand interactions. The ligands and their metal complexes were characterized with different analytical methods (1H, 13C, 31P NMR, COSY, NOESY, ESI-MS, MALDI-TOF HRMS, CD, and single crystal X-ray diffraction). The stereochemistry of the hydrogenation products was explained using stereochemical analysis and DFT calculations.
Wykazano, iż katalityczne odwodornienie iC 4 H 10 w obecności CO 2 może stanowić alternatywę dla obecnie stosowanych metod pozyskiwania izobutenu. Wyjściowe parametry procesu dobrano bazując na ...wynikach analizy termodynamicznej. Spośród katalizatorów tlenkowych osadzonych na krzemionce, pięciotlenek wanadu wybrano jako najbardziej aktywny tlenek w reakcji odwodornienia iC 4 H 10 w obecności CO 2 . Dalsze badania obejmowały optymalizację składu katalizatora poprzez dobór nośnika, masy V 2 O 5 , sposobu preparatyki i efektu wprowadzenia domieszek kationów metali. Najbardziej aktywny okazał się tlenek wanadu naniesiony na powierzchnię węgla aktywnego, dla którego konwersja alkanu w obecności CO 2 wyniosła 55% przy selektywności 80%, jednak ze względu na charakter nośnika, do dalszych badań nad rolą CO 2 w procesie odwodornienia iC 4 H 1 0 użyto kontaktów VMgOx. Oba katalizatory pozwoliły zaobserwować promujący wpływ CO 2 na stopień konwersji iC 4 H 10 w porównaniu z reakcją w helu. Testy prowadzono metodą ciągłą oraz impulsową, badano masę powstającego depozytu węglowego, a także możliwość regeneracji zdezaktywowanego kontaktu w strumieniu CO 2 oraz O 2 . Wyniki uzupełniono o charakterystykę fizykochemiczną katalizatorów (oznaczenia XRD, IR, SBET, EPR, UV-VIS, TPR, TPD, testowa reakcja rozkładu 2-proanolu, miareczkowania redoks). Stwierdzono, iż orto-Mg 3 (VO 4 ) 2 wykazuje najwyższą aktywność oraz powinowactwo do izobutanu spośród wszystkich faz V-Mg-O. Podstawową rolą CO 2 jest jego udział w reakcji RWGS.
It was shown that the catalytic dehydrogenation of iC 4 H 10 in the presence of CO 2 might be considered as an alternative method of obtaining isobutene. An initial process conditions were adjusted on the basis of thermodynamic calculations. Among various silica supported catalysts, vanadium oxide was chosen as the most active metal oxide in the iC 4 H 10 dehydrogenation reaction in the presence of CO 2 . Optimization of the catalyst composition (i.e. type of support, V 2 O 5 loading, effect of doping with metal cations), as well as method of the catalyst preparation were investigated at further experiments. The most active was active carbon supported vanadium oxide catalyst as the alkane conversion and selectivity to iC 4 H 8 in the presence of CO 2 were 55% and 80% respectively. However, the specific character of the support caused that further investigations were carried out over VMgOx catalysts. The both catalysts allowed observing the positive effect of CO 2 , i.e. the promotion of iC 4 H 10 conversion in comparison to the process under helium. The continuous-flow and pulse techniques were applied in the catalytic tests. Moreover, the coke deposition was investigated, as well as the possibility of the catalyst regeneration in CO 2 and O 2 stream. Comparison of these data with the study of physicochemical properties of catalysts (i.e., XRD, IR, SBET, ESR, UV-VIS, TPR, TPD, the results of 2-propanol decomposition test reaction and redox titration tests) showed that orto-Mg 3 (VO 4 ) 2 was the most active phase. The basic role of CO 2 in the process was its participation in RWGS reaction.
Razvijajući novi pristup sintezi antidota pri otrovanju organofosfatima kao i njihovu detekciju, primijenili smo metode rekombinantne DNA za pripremu kolinesteraza s neuobičajenim svojstvima. Za ...antidotsku terapiju istražili smo mutacije prirodnih enzima miša i čovjeka koje povećavaju brzine reaktivacije oksimom. Takvi enzimi bi po unosu u cirkulaciju postali katalitički, a ne samo stehiometrijski odstranjivači organofosfata. Na taj način “oksimom potpomognuta kataliza” omogućava čišćenje organofosfata iz cirkulacije umanjujući prodiranje organofosfata u tkiva i njihovu toksičnost. Prema tome, oksim kao antidot ima dvojaku ulogu: u cirkulaciji i na razini tkiva. S druge strane, uporabom novog sintetskog pristupa u oblikovanju biološki aktivnih spojeva poznatog kao “klik kemija” diskretnih proteinskih konformacija, organofosforilirani konjugati acetilkolinesteraze služe kao kalup u sintezi novih nukleofilnih reaktivatora. Naposljetku, acetilkolinesteraza se može mutagenezom modificirati uvo|enjem cisteina na koje se mogu vezati fluorofori. Fluorofori uvedeni na određena mjesta u molekuli acetilkolinesteraze mijenjaju svoja fluorescentna svojstva pri konjugaciji organofosfata s enzimom koji na taj način od objekta djelovanja insekticida i živčanih bojnih otrova postaje molekula za detekciju izloženosti organofosfatima.
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