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18 results on '"Bejan, Iulia"'

3. Transfer of a disilenyl moiety to aromatic substrates and lateral functional group transformation in aryl disilenes

Author

Jeck, Jonathan, Nied, Dominik, Breher, Frank, Scheschkewitz, David, Bejan, Iulia, and White, Andrew J.P.

Subjects
Lithium compounds -- Electric properties, Silicon compounds -- Electric properties, Titanium compounds -- Electric properties, Chemistry
Abstract

The reaction of 1 equiv of the disilenide [Tip.sub.2]Si[double bond]Si(Tip)Li (Tip = 2,4,6-[super i][Pr.sub.3][C.sub.6][H.sub.2]) with para-substituted phenyl iodides, 4-X-PhI, has transferred the [Tip.sub.2]Si[double bond]Si(Tip) moiety with elimination of lithium iodide to produce the laterally functionalized disilenes [Tip.sub.2]Si[double bond]Si(Tip)(4-X-Ph) [X = H, F, Cl, Br, I). The UV-vis absorptions of the functionalized disilenes have shown a linear correlation with electronic Hammett parameters.

Published
2010

5. Transfer of Si=Si double bonds on organic substrates: Stable conjugated systems vs. rearrangement reactions

Author

Bejan, Iulia Cornelia

Subjects
Umlagerung, ddc:540, Doppelbindung, Silicium, Konjugiertes System
Abstract

In dieser Arbeit wurde die Synthese und Charakterisierung von Systemen mit mehreren phenylen- oder vinylen-konjugierten Si=Si- bzw. C=Si-Doppelbindungen angestrebt. An diesen Verbindungen wurde die Art der Wechselwirkung sowie der Grad der Konjugation zwischen siliciumhaltigen Doppelbindungen und aromatischen Verknüpfungseinheiten untersucht. Auf diese Weise wurde die Grundlage für die Darstellung von Polymeren auf Basis dieser Bauelemente bereitet, um die aktuellen Entwicklungen von P=C- und P=P- Doppelbindungssystemen hin zu schwereren Analoga von Polyphenylenvinylen Copolymeren nachvollziehen zu können., In this thesis was shown that disilenide, i. e. disila analogue to vinyl anion, constitute an excellent reagent for the synthesis of new compounds with conjugated Si=Si double bonds. On the first model system for the silicon analogues of poly(phenylene-vinylene)s (PPVs) was established the conjugation of the two Si=Si moieties over the phenylene bridge. New compounds bearing cyclic and bicyclic structures were synthesised by the reaction of disilenid with unsaturated electrophiles. In a midterm time frame the availability of compounds with more than one Si=Si units will offer an alternative access to siliconpolymers. Moreover, the unique dual reactivity of disilenid provides new synthesic routes for the difficult access to the polycyclic ringsystems incorporating silicon atoms.

Published
2010

16. How Stress Factors Affect Electroless Affect Electroless: Many factors can impact internal stress, but tests show bath age and deposition rate are the biggest influencers.

Author

BEJAN, IULIA

Subjects
DEPOSITIONS, NICKEL-plating, STRESS measurement (Mechanics), COATING processes, THICKNESS measurement
Abstract

The article focuses on the role of bath age and deposition rate which impact on the internal stress in electroless nickel coatings in certain applications. Topics discussed include deflection method to measure stress in a coating, thickness of coating depending on factors such as volume, heat distribution and bath age, and effect of phosphorus incorporation.

Published
2018

18. Atmospheric oxidation of α,β-unsaturated ketones: kinetics and mechanism of the OH radical reaction.

Author

Illmann, Niklas, Gibilisco, Rodrigo Gastón, Bejan, Iustinian Gabriel, Patroescu-Klotz, Iulia, and Wiesen, Peter

Subjects
PEROXYACETYL nitrate, KETONES, FOURIER transform infrared spectroscopy, DIACETYL, ACETOIN, ACETALDEHYDE, OXIDATION
Abstract

The OH-radical-initiated oxidation of 3-methyl-3-penten-2-one and 4-methyl-3-penten-2-one was investigated in two atmospheric simulation chambers at 298±3 K and 990±15 mbar using long-path FTIR spectroscopy. The rate coefficients of the reactions of 3-methyl-3-penten-2-one and 4-methyl-3-penten-2-one with OH radicals were determined to be (6.5±1.2)×10-11 and (8.1±1.3)×10-11 cm3molecule-1s-1 , respectively. To enlarge the kinetics data pool the rate coefficients of the target species with Cl atoms were determined to be (2.8±0.4)×10-10 and (3.1±0.4)×10-10 cm3molecule-1s-1 , respectively. The mechanistic investigation of the OH-initiated oxidation focuses on the RO2+NO reaction. The quantified products were acetoin, acetaldehyde, biacetyl, CO2 and peroxyacetyl nitrate (PAN) for the reaction of 3-methyl-3-penten-2-one with OH radicals and acetone, methyl glyoxal, 2-hydroxy-2-methylpropanal, CO2 and peroxyacetyl nitrate (PAN) for the reaction of 4-methyl-3-penten-2-one with OH, respectively. Based on the calculated product yields an upper limit of 0.15 was determined for the yield of RONO2 derived from the OH reaction of 4-methyl-3-penten-2-one. By contrast, no RONO2 formation was observed for the OH reaction of 3-methyl-3-penten-2-one. Additionally, a simple model is presented to correct product yields for secondary processes. [ABSTRACT FROM AUTHOR]

Published
2021
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