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21.
Labeling conditions of synkavit (2-methyl-1,4-naphthoquinol disodium phosphate) with iodine-125 have been studied. In this study, labeling temperature, reaction time, successive using of iodogen coated tubes, iodogen amount and synkavit concentrations have been determined to get optimum conditions for maximum labeling. Final results showed that when the labeling temperature, reaction time, synkavit concentration, and iodogen amount were, at room temperature, 15 min (in the case of successive using of three iodogen coated tubes), 2 mg ml–1 and 5 mg, respectively; labeling yield was 90% and specific activities of the order of 555 GBq mmol–1 (15 Ci mmol–1) have been obtained. 相似文献
22.
ERGÜN KASAP SÜLEYMAN ÜZCELÍK 《Journal of inclusion phenomena and macrocyclic chemistry》1997,28(3):259-267
IR spectra of M(1,4-diaminobutane)Ni(CN)4° 1.5C6H6 (M = Mn, Fe, or Co), and IR and Raman spectra of M(1,4-diaminobutane)Ni(CN)4° 1.5C6H6 (M = Ni or Cd) clathrates are reported. The spectral features suggest that the compounds are similar in structure to the Hofmann-dabn-type clathrates. 相似文献
23.
It is shown that (−)-(S)-N,N-dimethyl-2-(1′-methylallyl)aniline ((−)-(S)- 4 ), on direct irradiation in MeCN at 20°, undergoes in its lowest-lying triplet state an aromatic di-π-methane (ADPM) rearrangement to yield (−)-(1′R,2′R)- and (+)-(1′R,2′S)-N,N-dimethyl-2-(2-methylcyclopropyl)aniline ((−)-trans- and (+)-cis- 7 ) in an initial trans/cis ratio of 4.71 ± 0.14 and in optical yields of 28.8 ± 5.2% and 15 ± 5%, respectively. The ADPM rearrangement of (−)-(S)- 4 to the trans- and cis-configurated products occurs with a preponderance of the path leading to retention of configuration at the pivot atom (C(1′) in the reactant and C(2′) in the products) for (−)-trans- 7 and to inversion of configuration for (+)-cis- 7 , respectively. The results can be rationalized by assuming reaction paths which involve the occurrence of discrete 1,4- and 1,3-diradicals (cf. Schemes 10, 12, and 13). A general analysis of such ADPM rearrangements which allows the classification of these photochemical reactions in terms of borderline cases is presented (Scheme 14). It is found that the optical yields in these ‘step-by-step’ rearrangements are determined by the first step, i.e. by the disrotatory bond formation between C(2) of the aromatic moiety and C(2′) of the allylic side chain leading to the generation of the 1,4-diradicals. Moderation of the optical yields can occur in the ring closure of the 1,3-diradicals to the final products, which may take place with different trans/cis-ratios for the individual 1,3-diradicals. Compounds (−)-trans- 7 as well as (+)-cis- 7 easily undergo the well-known photochemical trans/cis-isomerization. It mainly leads to racemization. However, a small part of the molecules shows trans/cis-isomerization with inversion of configuration at C(1′), which is best explained by a photochemical cleavage of the C(1′)–C(3′) bond. 相似文献
24.
In this work, the mechanochemical synthesis of a moderately agglomerated tin oxide (SnO2) powders and the subsequent preparation of semiconductor gas sensors as prototypes, were studied. Tin (II) chloride (SnCl2) powder was milled with calcium hydroxide (Ca(OH)2) and potassium carbonate, (K2CO3) powder, respectively, in a ball mill at room temperature and in an air atmosphere. Heat treatment of milled mixtures at 400 °C resulted in the formation of a tetragonal phase, confirmed by X-ray diffraction (XRD). During milling in the presence of water, a high number of hydroxide (OH) groups are formed at the surface. When SnCl2 was milled with K2CO3, no water was produced and the Fourier-transform infrared spectrum (FT-IR) of the powder has no surface hydroxyl deformations. On exposure to hydrogen sulfide (H2S) gas, the particles, prepared from anhydrous powder, have higher sensitivity than these, prepared from hydrated powder. The SnO2 thick film, prepared from anhydrous powder may be successfully applied to a H2S gas sensor. 相似文献
25.
Immobilization of Mercuric reductase from aPseudomonas putida strain on different activated carriers
F. B. Anspach M. Huckel M. Brunke H. SChÜTte W. D. Deckwer 《Applied biochemistry and biotechnology》1994,44(2):135-150
Mercuric reductase was isolated fromPseudomonas putida KT2442::mer-73 and immobilized on Chromatographic carriers activated by various methods. The immobilization methods for covalent coupling were compared with regard to preservation of enzymatic activity and coupling yields. Highest yields were obtained with carriers bearing the most reactive functional groups. Best results were achieved with tresyl chloride-activated carriers. The optimum binding conditions were found at pH 8. Application of the immobilized mercuric reductase for continuous treatment of Hg(II)-containing water was examined in a fixed bed reactor. Space-time yields up to 510 nmol/min-mL were attained. The kinetics of immobilized enzyme systems were not diffusion-controlled. 相似文献
26.
27.
Terhi Oja Petri Tähtinen Nadine Dreiack Pekka Mäntsälä Jarmo Niemi Mikko Metsä-Ketelä Karel D. Klika 《Tetrahedron: Asymmetry》2012,23(9):670-682
Two new pairs of stereoisomeric alnumycin As, A2 {(2)-(1R,1′RS,4′SR,5′SR)} and A3 {(2)-(1R,1′RS,4′SR,5′RS)}, are described. Similar to alnumycin A1 {(2)-(1R,1′RS,4′RS,5′SR)}, each of these naturally occurring compounds is also a pair of C-1 inverse epimers. The relative configurations of the dioxane ring sidechains were assigned on the basis of 1H NMR NOE contacts and molecular modeling using density functional theory (DFT) at the M06-2X/6-31G(d) level of theory. The absolute configurations of C-1 and the determination of inverse epimeric relationships were achieved by experimental electronic circular dichroism (ECD) measurements, with both aspects confirmed by using the chiral derivatizing agent (CDA) Mosher′s acid chloride {α-methoxy-α-trifluorophenylacetyl chloride (MTPACl)} to effect enantiodifferentiation. The absolute configurations of the dioxane ring using the CDA could only be effected in the case of alnumycin A1, the results of which were in agreement with previous assignments. The dioxane ring conformational mobility and the likely interaction between the MTPA groups coupled with the structural novelty of the diols in the dioxane ring with respect to CDA analysis precluded an absolute configuration assignment for alnumycins A2 and A3 based on empirical comparisons or by computational analysis of through-space NMR shieldings (TSNMRS) emanating from the phenyl groups of the MTPA moieties. 相似文献
28.
29.
Research on Chemical Intermediates - Palladium (II) complex with 4-tert-butylbenzoic hydrazide (TBBH)/triphenylphosphine (PPh3) ligands was successfully synthesized and characterized by X-ray,... 相似文献
30.
The electronic absorption spectrum of 1-chloromethyl hypochlorite ClCH2OCl is computed with multi-reference configuration interaction (MRD-CI) methods and compared to isomeric dichloromethanol. While the first dipole-allowed transitions of dichloromethanol Cl2CHOH are obtained above 7 eV, the corresponding transitions of ClCH2OCl are obtained at much lower energy, namely 3.66eV (11A″ ←[Xtilde]1A′), 4.96eV (21A′←[Xtilde]1A′), 6.04eV (21A″←[Xtilde]1A′) and 6.67eV (31A′ ← [Xtilde]1 A′). A further strong transition is computed at 7.82eV (41A′ ← [Xtilde]1A′) with a relatively large oscillator strength of ? = 0.4. 相似文献