Home About us Contact
|
Home About us Contact | ||
|
|
||
Reaction Chemistry (reaction + chemistry)
Selected AbstractsReaction Chemistry of 1,4-Benzopyrone Derivates in Non-Equilibrium Low-Temperature PlasmasPLASMA PROCESSES AND POLYMERS, Issue 6 2010Franziska Grzegorzewski Abstract 1,4-Benzopyrone derivates are exposed to different cold gas discharges. Reactions are carried out using different feed gases (argon, oxygen) and excitation sources (radio frequency, microwave) at both atmospheric and low pressure. A structure-dependent degradation upon plasma-chemical reactions can be observed. From contact-angle measurements a strong surface oxidation is suggested. Independent of the source used plasma treatment leads to a significant increase in oxygen content of the samples through newly introduced carbonyl- and carboxyl-functions. This is in agreement to results showing that during thermal food processes oxidative species lead to the formation of characteristic low-molecular weight degradation products. [source] ChemInform Abstract: Cyclohepta[de]naphthalenes and the Rearranged Abietane Framework of Microstegiol via Nicholas Reaction Chemistry.CHEMINFORM, Issue 22 2009Rafiq A. Taj Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] cis-Enhanced Cyclopropanation Catalysts: Reaction Chemistry of Three Isomers of Rh2[N(C6H5)COCH3]4.CHEMINFORM, Issue 26 2003Cassandra T. Eagle Abstract For Abstract see ChemInform Abstract in Full Text. [source] Fire-resistant cyanate ester,epoxy blendsFIRE AND MATERIALS, Issue 4 2003Richard N. Walters Abstract The cure chemistry, thermal stability and fire behaviour of a series of fire-resistant cyanate ester,epoxy blends were examined. The dicyanate and diepoxide of 1, 1-dichloro-2, 2-bis(4-hydroxyphenyl)ethylene (bisphenol-C, BPC) were combined in various molar ratios and the reaction chemistry was monitored using Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The fire behaviour of the BPC cyanate,epoxy blends was studied in flaming and non-flaming combustion, using OSU calorimetry and pyrolysis-combustion flow calorimetry (PCFC), respectively. Published in 2003 by John Wiley & Sons, Ltd. [source] QSARs for the skin sensitization potential of aldehydes and related compoundsMOLECULAR INFORMATICS, Issue 2 2003Grace Patlewicz Abstract Although not all aldehydes are skin sensitizers, many of them, covering a diverse range of structures, show varying degrees of sensitization potential. Based on consideration of their reaction chemistry, it is possible to identify structural features associated with sensitization potential or the lack of it. Many aldehydes, including several fragrance allergens, can sensitize by Schiff base formation. A QSAR based on reactivity and hydrophobicity parameters has been developed for these aldehydes. The QSAR can be extended to include 1,2-diketones, which can also react by Schiff base formation. The findings indicate that for skin sensitization, as for several other areas of toxicology, chemicals are better classified in terms of their reaction chemistry rather than in terms of their functional groups, i.e., based on mechanisms of action as opposed to chemical class. [source] Enhancement and rescue of target capture in Tn10 transposition by site-specific modifications in target DNAMOLECULAR MICROBIOLOGY, Issue 4 2004Patrick A. Pribil Summary The bacterial transposon Tn10 inserts preferentially into specific target sequences. This insertion specificity appears to be linked to the ability of target sites to adopt symmetrically positioned DNA bends after binding the transposition machinery. Target DNA bending is thought to permit the transposase protein to make additional contacts with the target DNA, thereby stabilizing the target complex so that the joining of transposon and target DNA sequences can occur efficiently. In the current work, we have asked whether the introduction of a discontinuity in a target DNA strand, a modification that is expected to make it easier for a DNA molecule to bend, can enhance or rescue target capture under otherwise suboptimal reaction conditions. We show that either a nick or a missing phosphate specifically at the site of reaction chemistry increases the ability of various target DNAs to form the target capture complex. The result suggests that the bends in the target DNA are highly localized and include the scissile phosphates. This raises the possibility that strand transfer is mechanistically linked to target capture. We have also identified specific residues in the target DNA and in transposase that appear to play an important role in target DNA bending. [source] Growth Per Cycle in Atomic Layer Deposition: Real Application Examplesof a Theoretical Model,CHEMICAL VAPOR DEPOSITION, Issue 6 2003R.L. Puurunen Abstract In a previous paper, a theoretical model was derived to describe the growth per cycle in atomic layer deposition (ALD) as a function of the chemistry of the growth when compounds are used as reactants. This paper presents examples of how the model can be applied to investigate the mechanisms of real ALD processes. Three processes that represent different classes of compound reactants were selected for study: the trimethylaluminum/water process to grow aluminum oxide, the yttrium 2,2,6,6-tetramethyl-3,5-heptanedionate (thd)/ozone process to grow yttrium oxide, and the titanium tetrachloride/water process to grow titanium dioxide. The results obtained by applying the model were, in general, consistent with the results obtained through separate investigations of the reaction mechanisms. The model was shown to be a useful tool in investigations of the reaction chemistry of real ALD processes. [source] Mixed-Transition-Metal Acetylides: Synthesis and Characterization of Complexes with up to Six Different Transition Metals Connected by Carbon-Rich Bridging UnitsCHEMISTRY - A EUROPEAN JOURNAL, Issue 16 2008Rico Packheiser Dipl.-Chem. Abstract The synthesis and reaction chemistry of heteromultimetallic transition-metal complexes by linking diverse metal-complex building blocks with multifunctional carbon-rich alkynyl-, benzene-, and bipyridyl-based bridging units is discussed. In context with this background, the preparation of [1-{(,2 -dppf)(,5 -C5H5)RuCC}-3-{(tBu2bpy)(CO)3ReCC}-5-(PPh2)C6H3] (10) (dppf=1,1,-bis(diphenylphosphino)ferrocene; tBu2bpy=4,4,-di- tert -butyl-2,2,-bipyridyl; Ph=phenyl) is described; this complex can react further, leading to the successful synthesis of heterometallic complexes of higher nuclearity. Heterotetrametallic transition-metal compounds were formed when 10 was reacted with [{(,5 -C5Me5)RhCl2}2] (18), [(Et2S)2PtCl2] (20) or [(tht)AuCC-bpy] (24) (Me=methyl; Et=ethyl; tht=tetrahydrothiophene; bpy=2,2,-bipyridyl-5-yl). Complexes [1-{(,2 -dppf)(,5 -C5H5)RuCC}-3-{(tBu2bpy)(CO)3ReCC}-5-{PPh2RhCl2(,5 -C5Me5)}C6H3] (19), [{1-[(,2 -dppf)(,5 -C5H5)RuCC]-3-[(tBu2bpy)(CO)3ReCC]-5-(PPh2)C6H3}2PtCl2] (21), and [1-{(,2 -dppf)(,5 -C5H5)RuCC}-3-{(tBu2bpy)(CO)3ReCC}-5-{PPh2AuCC-bpy}C6H3] (25) were thereby obtained in good yield. After a prolonged time in solution, complex 25 undergoes a transmetallation reaction to produce [(tBu2bpy)(CO)3ReCC-bpy] (26). Moreover, the bipyridyl building block in 25 allowed the synthesis of Fe-Ru-Re-Au-Mo- (28) and Fe-Ru-Re-Au-Cu-Ti-based (30) assemblies on addition of [(nbd)Mo(CO)4] (27), (nbd=1,5-norbornadiene), or [{[Ti](,-,,,-CCSiMe3)2}Cu(NCMe)][PF6] (29) ([Ti]=(,5 -C5H4SiMe3)2Ti) to 25. The identities of 5, 6, 8, 10,12, 14,16, 19, 21, 25, 26, 28, and 30 have been confirmed by elemental analysis and IR, 1H, 13C{1H}, and 31P{1H} NMR spectroscopy. From selected samples ESI-TOF mass spectra were measured. The solid-state structures of 8, 12, 19 and 26 were additionally solved by single-crystal X-ray structure analysis, confirming the structural assignment made from spectroscopy. [source] | |||||||||||||