Treatment Of Reaction Mixture Research Articles

Gold(I) {2}‐Metallacoronates derived from a Catechol‐scaffolding Aroylbis(N,N‐diethylthiourea): Syntheses and Structures

AbstractOne‐pot reactions of catechol‐scaffolding aroylbis(N,N‐diethylthiourea) H2Lcat and mixtures of lanthanide nitrates Ln(NO3)3 (Ln3+=La3+, Nd3+ or Yb3+) or indium(III) chloride InCl3 and [Au(tht)Cl] in methanol in the presence of the supporting base Et3N result in gold(I) {2}‐metallacoronates. Depending on radii of the trivalent metal ions, the corresponding complexes are separated either in the neutral form with the composition {(NO3‐κ2‐O,O’)Ln⊂[Au2(Lcat)2]} in the cases of La3+ and Nd3+ or as the ‘ion‐pair’ {Yb⊂[Au2(Lcat)2]}+(NO3)− for the Yb(III) compound. The cationic complexes can be isolated in higher yields as the PF6− salts {M⊂[Au2(Lcat)2]}+(PF6)− (M3+=Yb3+ or In3+) by treatment of reaction mixtures with (n‐Bu4N)(PF6).

Lanthanoid Biphenolates as a Rich Source of Lanthanoid-Main Group Heterobimetallic Complexes.

Several new trivalent dinuclear rare earth 2,2’‐methylenebis(6‐tert‐butyl‐4‐methylphenolate) (mbmp2−) complexes with the general form [Ln2(mbmp)3(thf)n] (Ln=Sm 1, Tb 2 (n=3), and Ho 3, Yb 4 (n=2), and a tetravalent cerium complex [Ce(mbmp)2(thf)2] (5) have been synthesised by RTP (redox transmetallation/protolysis) reactions from lanthanoid metals, Hg(C6F5)2 and the biphenol mbmpH2. These new complexes and some previously reported partially protonated rare earth biphenolate complexes [Ln(mbmp)(mbmpH)(thf)n] react with lithium, aluminium, potassium and zinc organometallic reagents to form lanthanoid‐main group heterobimetallic species. When reaction mixtures containing the Ln biphenolate complexes were treated with n‐butyllithium, both molecular ([Li(thf)2Ln(mbmp)2(thf)n] (Ln=La 6, Pr 7 (n=2) and Er 8, Yb 9, and Lu 10 (n=1)) and charge separated ([Li(thf)4][Ln(mbmp)2(thf)2] (Ln=Y 11, Sm 12, Dy 13, and Ho 14) complexes were isolated. Treatment with trimethylaluminium also led to isolation of molecular ([AlMe2Ln(mbmp)2(thf)2] (Ln=Pr 15, Sm 16, and Tb 17)) and ionic [La(mbmp)(thf)5][AlMe2(mbmp)] (18) complexes. One gadolinium‐potassium ([K(thf)3Gd(mbmp)2(thf)2] (19)), and one ytterbium‐zinc species ([ZnEtYb(mbmp)2(thf)] (20)) were isolated from treatment of reaction mixtures with potassium bis(trimethylsilyl)amide and diethylzinc respectively.

Hydroxyapatite for Filling Bone Tissue Defects

Hydroxyapatite was synthesized in conditions of mechanoacoustic treatment of an aqueous reaction mixture consisting of ammonium hydrogen phosphate and calcium nitrate using a commercially available rotary pulsation apparatus. Mechanoacoustic treatment of the reaction mixture was found to lead to the formation of nanosized hydroxyapatite particles with a predominant mean diameter of about 20 nm. Purification of technical hydroxyapatite to remove traces of ammonium nitrate by thermal processing at 350°C is proposed. The crystalline phase of hydroxyapatite was found not to be dominant in the structure. The porosity of hydroxyapatite amounted to about 75% with a mean pore diameter of 2.8 × 103 nm. Thermal processing of hydroxyapatite in aqueous medium was found to yield a paste-like form. Hydroxyapatite paste had no cytotoxicity and did not prevent cell adhesion, though it almost completely inhibited cell spreading.

Synthesis, structure and thermal expansion of the phosphates M0.5+x M′ x Zr2−x (PO4)3 (M, M′–metals in oxidation state +2)

Abstract The phosphates M0.5+x M′ x Zr2−x (PO4)3 (M–Ca, Mn, Co, Sr, Cd, Ba, Pb; M′–Mg, Mn, Co) were synthesized by sol-gel method with the following thermal treatment of reaction mixtures. X-ray diffraction, IR spectroscopy and electron microprobe analysis showed that the obtained phosphates crystallized in Sc2(WO4)3 (SW) and NaZr2(PO4)3 (NZP) structural types. Both types of crystal structures are based on a framework comprised of octahedra and tetrahedra, the difference between them is fragments orientation. Thermal expansion of the phosphates was studied in the temperature range 20–800°C. Some compounds were found to belong to low-expanding materials (αav ~2·10−6°C−1).

Synthesis of bis‐ and tris‐organophosphorus substituted amines and amino acids with PCH2N Fragments

AbstractThe aminomethylation of the derivatives of trivalent organophosphorus acids, containing PH and POSiMe3 fragments with various bis‐ and tris(alkoxymethyl)amines and bis(alkoxymethyl)amino acids, is proposed as a convenient method for the synthesis of new bis‐ and trisphosphorylated amines and amino acids as well as their derivatives with four and five coordinated phosphorus. Also the three‐components systems of phosphorous acid, paraformaldehyde, and amines are thoroughly investigated via the treatment of reaction mixtures with bis(trimethylsilyl)amine. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:430–440, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20616

Synthesis of 2-arylbenzoxazoles via DDQ promoted oxidative cyclization of phenolic Schiff bases—a solution-phase strategy for library synthesis

The Schiff base derived from the condensation of o-aminophenol with benzaldehydes was induced to undergo oxidative cyclization in the presence of DDQ. The resulting 2-arylbenzoxazoles were separated from the reduced DDQ byproduct by treatment of reaction mixture with a strongly basic ion-exchange resin. The applicability of this chemistry to spatially separate library synthesis is demonstrated by the preparation of a 352-member library.

Platinum promoting effects in Pt/Ga zeolite Catalysts of lower alkane aromatization. I. Ga and Pt electronic states, dispersion and distribution in zeolite crystals in dependence of preparation techniques. Dynamic effects caused by reaction mixture

X-ray photoelectron spectroscopy (XPS), infrared (IR), electron microscopy (EM) and energy dispersive X-ray (EDAX) studies of in various ways prepared Ga/H-ZSM-5, Pt-Ga/H-ZSM-5 as well as Ga-silicate and Pt/Ga-silicate have been performed. The external surface of the zeolite crystal was originally strongly enriched with a Ga 2O 3 phase the dispersion of which depends on the preparation as well. Ga reduction, evidenced by XPS Ga 3d line shifts, occurred during reduction and/or the reaction mixture treatment and it was accompanied by migration of Ga I cations into the zeolite channels. The migration of unreduced Ga III species via solid-state reactions is less pronounced. The gallium reduction and migration is dramatically promoted by platinum introduced into both Ga/H-ZSM-5 and Ga-silicate; the reduction degree in the last sample is limited by the concentration of the extra-framework Ga III ions. Platinum was shown to be finely dispersed in highly acidic Pt-Ga/H-ZSM-5 while most of the platinum formed aggregates (30–50A˚) on the external surface of Ga-silicate. IR of adsorbed hydrogen and pyridine confirmed that reduction results in the formation of new strong Lewis acidic sites. Along with Ga I-HZ and Ga IIHZ structures mixed Pt-Ga particles located within the zeolite structure are most likely to be responsible for the dramatic enhancement of the aromatic selectivity found with Pt-Ga/zeolite catalysts (see Part II).

Trapping of an intermediate in the reaction catalyzed by 5-oxoprolinase.

Bacterial 5-oxoprolinase is composed of two protein components: Component A, which catalyzes 5-oxoproline-dependent ATP-hydrolysis and Component B, which couples the hydrolysis of ATP with the decyclization of 5-oxoproline to form glutamate (Seddon, A. P., Li, L., and Meister, A. (1984) J. Biol. Chem. 259, 8091-8094). Studies on this unusual enzyme system have led to evidence that an intermediate is formed by Component A. Application of the isotope-trapping method demonstrated an activated 5-oxoproline intermediate, whose formation requires ATP, Mg2+, and Component A. The amount of ATP-dependent trapping was close to the number of enzyme active sites. The intermediate formed by Component A was shown to be reducible by potassium borohydride to proline in low yield; when Component B was added, the formation of proline was abolished. Treatment of reaction mixtures containing Component A, 5-oxoproline, and [gamma-32P] ATP with diazomethane led to appearance of a 32P-labeled compound (found on thin layer chromatography), whose formation was significantly reduced when Component B was present. The new compound, which is labile, breaks down to form dimethyl[32P]phosphate. The total amount of dimethyl[32P]phosphate formed after breakdown is close to the number of active sites of Component A. The data are consistent with the conclusion that a phosphorylated form of 5-oxoproline is formed by Component A and suggest that Component B is required for conversion of this intermediate to glutamate.

The comparison of differences in reiterated sequences by RNA-DNA hybridisation.

HE technique of hybridisation has been widely used in the determination of base sequence homologies. The Carnegie Institution group pioneered the application of DNA-DNA hybridisation to the comparison of sequence differences between a wide range of species (HOYER, MCCARTHY and BOLTON 1964), while differences between rat and mouse have been studied by MCLAREN and WALKER (1966). Since hybridisation between DNA: DNA and RNA: DNA are essentially similar reactions RNA-DNA hybridisation may be used to detect genetic differences, provided the RNA is sufficiently representative of the sequences we wish to compare. Recently, BRITTEN and KOHNE (1967) have shown that the DNA of higher organisms includes a substantial fraction of reiterated sequences and that the earlier DNA-DNA comparisons referred to such fractions rather than whole genomes. The interpretation of these sequences is obscure and we need further information about differences between them, especially in related species. The present paper deals with such evidence, which is based on the method of RNA-DNA hybridisation, in which the RNA is synthesised in vitro (cRNA) with the aid of DNAdependent RNA polymerase and appropriate DNA primers. Although nearest-neighbour analysis shows good agreement between cRNA and the primer DNA (WEISS and NAKAMOTO 1961), it cannot be assumed that all sequences are equally transcribed. If there are species differences in the frequency of preferred sites of transcription, this will enhance apparent genome differences, and, in some situations, this may be an advantage. The use of hybridisation between DNA and cRNA has several attractions which prompted the experiments described here. It is often difficult or excessively labourious to prepare, for DNADNA hybridisation, labelled DNA in sufficient quantity and of adequate specific activity from species which may be of particular interest for reiterated sequence comparisons. Subject to the qualifications noted above, the cRNA method is a general one and the RNA may be made with any desired specific activity. Also, convenient techniques, based on the use of membrane filters, have been developed by NYGAARD and HALL ( 1964), and by GILLESPIE and SPIEGELMAN ( 1965) for the quantitative measurement of RNA bound to DNA. Finally, the treatment of reaction mixtures with RNAase offers a fairly stringent test of complementarity. 1 This paper is dedicated to Dr. THEODOSIUS DOBZHANSKY, in recognition of his outstanding contributions to the genetics of natural populations and of evolutionary processes.