Search results for "Yield"
showing 10 items of 1338 documents
Synthesis of a technetium-99m labelledL-tyrosine derivative with thefac-99mTc(I)(CO)3-core using a simple kit-procedure
2004
Summary The synthesis of a novel technetium-99m labelled derivative of l-tyrosine as a potential tumour imaging agent for nuclear medicine diagnosis is reported. The synthesis involved the labelling precursor fac-[ 99m Tc(OH2)(CO)3] + which was synthesized using the commercially available Isolink 1 -labelling kit and the tyrosine derivative O-(N,Nbis(carboxymethyl)aminoethyl)-l-tyrosine trifluoroacetate. The labelled compound O( 99m Tc(I)-tricarbonyl-N,N-bis(carboxymethyl)aminoethyl)-l-tyrosine was obtained in a radiochemical yield of 70–80% within 60 min with a radiochemical purity greater than 98% without any HPLC purification step. Purification was achieved merely by solid phase extracti…
Molecular structure of the compound [Rh2(O2CCH3)3{(C6H4)P(BrC6H4-1,2)(C6H5)} · (HO2CCH3)2].Kinetic study of the exchange reaction of acetate groups w…
1993
Abstract The compound [Rh 2 (O 2 CCH 3 ) 3 {(C 6 H 4 )P(BrC 6 H 4 -1,2) (C 6 H 5 )} · (HO 2 CCH 3 ) 2 ] has been isolated in high yield from the thermal reaction of dirhodium tetraacetate and the phosphine P(BrC 6 H 4 -1,2) (C 6 H 5 ) 2 in acetic acid. The structure of this compound has been determined by X-ray diffraction; it crystallizes in the P 1 (triclinic) space group and contains three acetate groups bridging a Rh 2 4+ unit the RhRh distance being 2.432(1)A; the fourth bridging ligand is an ortho -bromophenyldiphenylphosphine metallated at one of the ortho positions of the unsubstituted phenyl rings. Two molecules of acetic acid occupy the axial coordination positions. Stepwise exch…
Cyclometallation reactions in complexes of the type Rh(oq)(CO)(P(o-BrC6F4)Ph2)
1986
Abstract The reaction of Rh(oq)(CO)(PCBr) (PCBr = P(o-BrC6F4)Ph2; oq = 8-oxyquinolinte)_ in refluxing toluene in the presence of Et4NBr (1/4 molar ratio) gives Rh(oq)Br(PC) (H2O), PC = P (o-C6F4)Ph2, in practically quantitative yield. The water molecule is readily displaced by various P-donor ligands to give complexes of general formula Rh(oq)Br(PC) PR3 (PR3 = PPh3, P(p-MeC6H4)3, P(p-MeOC6H4)3, P(p-FC6H4)3, P(PMe)3 and P(OPh3). The molecular structure of the compound Rh(oq)Br(PC) (PPh3) has been determined by X-ray methods. Crystals of the title compound are monoclinic, space group P21/n with unit cell dimensions a 11.273(4), b 20.087(8), c 17.471(7) A and β 102.15(8)°. The final R for 2304…
Azoxybenzene rearrangement catalyzed by solid acids
2008
Abstract For the first time, the potential of acidic cation-exchange resin (sulfonated polystyrene) to catalyze the Wallach rearrangement of azoxybenzene into 4-hydroxyazobenzene has been proved. This finding reveals an alternative reaction path possible in a heterogeneous process using solid acids and may help to clear some doubts concerning the rearrangement mechanism postulated so far. The resin-induced reaction was found to proceed exclusively in a non-polar medium. Reasonable yield was obtained particularly in isooctane due to favorable distribution of azoxybenzene throughout the resin's matrix. On the contrary, the HY type zeolite did not activate the rearrangement, most probably beca…
Ag44(EBT)26(TPP)4Nanoclusters With Tailored Molecular and Electronic Structure
2021
Although atomically precise metalloid nanoclusters (NCs) of identical size with distinctly different molecular structures are highly desirable to understand the structural effects on the optical and photophysical properties, their synthesis remains highly challenging. Herein, we employed phosphine and thiol capping ligands featuring appropriate steric effects and synthesized a charge-neutral Ag NC with the formula Ag44 (EBT)26 (TPP)4 (EBT: 2-ethylbenzenethiolate; TPP: triphenylphosphine). The single-crystal X-ray structure reveals that this NC has a hollow metal core of Ag12 @Ag20 and a metal-ligand shell of Ag12 (EBT)26 (TPP)4 . The presence of mixed ligands and long V-shaped metal-ligand …
Impact of the use of sterically congested Ir(III) complexes on the performance of light-emitting electrochemical cells
2018
International audience; The synthesis, structural and optoelectronic characterization of a family of sterically congested cyclometalated cationic Ir(iii) complexes of the form [Ir(C^N)2(dtBubpy)]PF6 (with dtBubpy = 4,4′-di-tert-butyl-2,2′-bipyridine and C^N = a cyclometalating ligand decorated at the 4-position of the pyridine ring and/or the 3-position of the phenyl ring with a range of sterically bulky substituents) are reported. This family of complexes is compared to the unsubstituted analogue complex R1 bearing 2-phenylpyridinato as cyclometalating ligand. The impact of sterically bulky substituents on the C^N ligands on both the solid state photophysics and light-emitting electrochemi…
ChemInform Abstract: Synthesis of New 2-(((Phenoxy or Phenyl)acetyl)amino)benzoic Acid Derivatives as 3α-Hydroxysteroid Dehydrogenase Inhibitors and …
2010
A number of 2-([(phenoxy or phenyl)acetyl]amino)benzoic acid derivatives were prepared in about 50% yield from (phenoxy or phenyl)acetyl chloride and anthranilic acid derivatives. All the compounds were tested as in vitro inhibitors of 3 alpha-hydroxysteroid dehydrogenase, since enzyme inhibition predicts potential antiinflammatory activity in vivo. The most active compounds 3 l, m, s are about 3.5 times more active than acetylsalicylic acid (ASA). Activity is influenced by electronic as well as steric effects.
Iodocyclization of o-Alkynylbenzamides Revisited: Formation of Isobenzofuran-1(3H)-imines and 1H-Isochromen-1-imines Instead of Lactams
2012
The iodocyclization of o-alkynylbenzamides with various electrophiles has been reported to yield five- or six-membered lactams by nucleophilic attack of the amide nitrogen onto the triple bond. While the formation of an isobenzofuran-1(3H)-imine with two bulky substituents under Larock conditions was initially attributed to steric hindrance, we found out that cyclization via the amide oxygen is the rule rather than the exception. Thus, the structures of the products reported in the literature need to be revised.
Deficit irrigation does not affect alternate bearing of ‘Valencia’ orange trees
2018
This study evaluated the effect of long-term partial rootzone drying and continuous deficit irrigation on the degree of alternate bearing of adult ‘Valencia’ orange trees grown in northern Sicily. Three irrigation strategies were imposed in summer from 2007 to 2011: irrigation with volumes corresponding to 100% of crop evapotranspiration applied to entire rootzone (CI), partial rootzone drying (PRD) with 50% of CI water applied to one alternated side of the rootzone, and continuous deficit irrigation (CDI) with 50% of CI water applied to both sides of the rootzone. The experiment was conducted on 48 adult orange trees arranged according to a randomized block design. Weather and soil paramet…
Effect of water on glass transition in starch/sucrose matrices investigated through positron annihilation lifetime spectroscopy: a new approach
2011
Glass transition is studied through positron annihilation lifetime spectroscopy (PALS) in maize starch matrices containing 10 (batch STS10) and 20 (STS20) w/w% sucrose, as a function of temperature (T) and water content (c(w)). To circumvent important losses of water upon heating while recording the PALS spectra, a new method is developed: instead of a series of measurements of τ(3), the triplet positronium lifetime, at different T, the latter is kept constant and the series relates to c(w), which is left to decrease at a constant rate. Similarly to the changes in τ(3) with T, the τ(3)vs. c(w) plots obtained show a smooth linear increase until a break, denoting the occurrence of glass trans…