Search results for "ISOC"
showing 10 items of 301 documents
A Versatile Synthesis of Fluorinated Uracils in Solution and on Solid-Phase.
2004
[reaction: see text] An efficient and convenient two-step synthesis of new fluorinated uracils is described. The first step involves the condensation of an ester enolate with a fluorinated nitrile to furnish fluorinated beta-enamino esters. In turn, these compounds react with organic isocyanates or isothiocyanates to give C-6 fluorinated uracils or thiouracils, respectively, in excellent yields. This synthesis has been successfully adapted to solid-phase conditions with high diversity, thereby facilitating the creation of small (thio)uracil libraries.
Involvement of the long arm of chromosome 9 in medulloblastoma in an adult.
1997
Abstract Medulloblastoma is the most common primitive neuroectodermal tumor (PNET) in children, but is very rare in adults. An isochromosome for the long arms of 17, i(17q), is found in about 30% of pediatric cases. Cytogenetic studies in adults are very scarce; only six cases have been described cytogenetically: three cases had normal karyotype, two were studied partially, and another presented only two clonal structural anomalies: del(9)(q12) and del(11)(q22). We studied the chromosomes from medulloblastoma in a 27-year-old woman and found one hypotetraploid stemline with clonal alterations. In the structural anomalies, chromosomes 3, 9, 12, and i(17q) were involved. Chromosome 9 presente…
ChemInform Abstract: Glycoside Synthesis via Electrophile-Induced Activation of N-Allyl Carbamates.
2010
Abstract O-Benzyl-, O-acyl-, N-acyl- and isopropylidene-protected glycosyl N-allylcarbamates, obtained from anomerically unprotected monosaccharides and allyl isocyanate, are activated by an electrophile-induced cyclisation and react with hydroxyl compounds to form the corresponding glycosides.
Reaction between Indazole and Pd-Bound Isocyanides-A Theoretical Mechanistic Study
2018
The mechanism of the addition of indazole (Ind)&mdash
Transparent thermoplastic polyurethanes based on aliphatic diisocyanates and polycarbonate diol
2016
Segmented thermoplastic polyurethanes (PUs) were synthetized using polycarbonate diol as soft segment with a molar mass of 500 and as a hard segment 1,5-pentanediol with a combination of isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI). Differential scanning calorimetry, differential mechanical analysis, Fourier transform infrared-attenuated total reflection spectroscopy, haze, transmittance, hardness, tensile properties and retention of tensile properties tests were employed to characterize the different PUs. The results of this study show that IPDI/HDI relation has a significant impact on the phase mixing, crystallinity and therefore on the PU’s properties. The variati…
PdII-mediated integration of isocyanides and azide ions might proceed via formal 1,3-dipolar cycloaddition between RNC ligands and uncomplexed azide
2016
Reaction between equimolar amounts of trans-[PdCl(PPh3)2(CNR)][BF4] (R = t-Bu 1, Xyl 2) and diisopropylammonium azide 3 gives the tetrazolate trans-[PdCl(PPh3)2(N4t-Bu)] (67%, 4) or trans-[PdCl(PPh3)2(N4Xyl)] (72%, 5) complexes. 4 and 5 were characterized by elemental analyses (C, H, N), HRESI+-MS, 1H and 13C{1H} NMR spectroscopies. In addition, the structure of 4 was elucidated by a single-crystal X-ray diffraction. DFT calculations showed that the mechanism for the formal cycloaddition (CA) of N3− to trans-[PdCl(PH3)2(CNMe)]+ is stepwise. The process is both kinetically and thermodynamically favorable and occurs via the formation of an acyclic NNNCN-intermediate. The second step of the fo…
La legge di Okun e le trasformazioni del Mercato del Lavoro
2007
Okun’s law turns out from the relationship between economic growth and unemployment fluctuations of the American economy during the sixties. Following Okun’s conclusions several analysis tried to test the empirical relevance of the initial relation for different countries and historical periods. In this paper we propose an empirical application regarding Italian regions. As we have observed the inconsistency of Okun’s Law for the south of Italy, we tried to test the reason for the absence of significance in the analysed coefficients. Observing the particularly low levels of participation to labour market in this area, we propose other labour market indicators more compatible with a delayed …
Numerical dating of the Eckfeld maar fossil site, Eifel, Germany: a calibration mark for the Eocene time scale.
2000
Sediments of the Eckfeld maar (Eifel, Germany) bear a well-preserved Eocene fauna and flora. Biostratigraphically, Eckfeld corresponds to the Middle Eocene mammal reference level MP (Mammals Paleogene) 13 of the ELMA (European Land Mammal Age) Geiseltalian. In the maar crater, basalt fragments were drilled, representing explosion crater eruption products. By 40Ar/39Ar dating of the basalt, for the first time a direct numerical calibration mark for an Eocene European mammal locality has been established. The Eckfeld basalt inverse isochron date of 44.3 +/- 0.4 Ma suggests an age for the Geiseltalian/Robiacian boundary at 44 Ma and, together with the 1995 time scale of Berggren et al., a time…
Identification and Evaluation of Hazardous Pyrolysates in Bio-Based Rigid Polyurethane-Polyisocyanurate Foam Smoke
2021
In this study, rigid polyurethane (PU) and polyisocyanurate (PIR) foam samples made from renewable material (tall oil fatty acid) based polyols were analyzed by pyrolysis gas chromatography mass spectrometry (Py-GC/MS) to obtain information about the full relative smoke content, with a focus on substance identification by their functional groups and hazardousness. The relative content of gaseous products produced during the thermal degradation was evaluated between the two samples, differenced by their assigned isocyanate (NCO) index value—150 and 300. The main thermal degradation components of the rigid PU-PIR foam were found to originate from the decomposition of isocyanate, primarily for…
Vergleichende kinetische untersuchungen über die basenkatalysierte reaktion von oligomethylen- und oligoäthylenglykolen mit phenylisocyanat
1961
Die durch Triathylamin katalysierte Reaktion von Oligomethylenglykolen und von Oligoathylenglykolen mit Phenylisocyanat in Dioxan bei 25°C wurde untersucht. Die Reaktionsgeschwindigkeit innerhalb der homologen bzw. polymerhomologen Reihe ist unter den angewandten Bedingungen unabhangig von der Kettenlange und der chemischen Struktur der Kette. The reaction of oligomethylene glycols (I) and oligooxyethylene glycols (II) with phenyl isocyanate in dioxane at 25°C. catalyzed by triethylamine was investigated. Under the applied conditions the reaction rate within the homologous and polymerhomologous series is independent of the chain length and the chemical constitution of the chain.