Single-stage Synthesis Research Articles

Cross-condensation of derivatives of cyanoacetic acid and carbonyl compounds. Part 1: Single-stage synthesis of 1′-substituted 6-amino-spiro-4-(piperidine-4′)-2H,4H-pyrano[2,3-c]pyrazole-5-carbonitriles

To develop a method of synthesis of the potentially physiologically active compounds, 1′-substituted 6-amino-spiro-4-(piperidine-4′)-2H,4H-pyrano[2,3-c]pyrazoles, we studied the three-component condensation of substituted piperidin-4-ones, malononitrile and pyrazolin-5-ones. It was found that the electrochemical method of synthesis is more regioselective, the products of the reaction are analytically pure and do not require further recrystallization.

Preparation of monodisperse PMMA microspheres in nonpolar solvents by dispersion polymerization with a macromonomeric stabilizer

We discuss a dispersion polymerization procedure for pre- paring monodisperse and micron- sized poly(methyl methacrylate) (PMMA) particles in hexanes with methacryloxypropyl-terminated polydimethylsiloxane stabilizers. We investigate the effects of the stabi- lizer molecular weight, stabilizer concentration, and monomer con- centration on the particle size and polydispersity. We find that a mini- mum molecular weight of 10 000 g/mol is necessary to synthesize col- loidally stable PMMA dispersions. The particle polydispersity is mini- mal ( £ 5%) for stabilizer to mono- mer weight ratios of 0.02 to 0.1, while PMMA particles prepared under conditions outside this range are polydisperse. The particle diameter can be varied from 0.4 to 1.5 lm by appropriate choices of stabilizer and monomer concentra- tions. Stable PMMA suspensions can be prepared at up to 26.3% solids. The dispersions are stable in most liquid aliphatics, and are monodisperse enough to form or- dered domains at high concentra- tion. This single-stage synthesis, requiring only commercially avail- able materials, may be of interest to those seeking a simple way to pre- pare highly monodisperse non- aqueous dispersions in the micron size range.

Synthesis of protein A conjugates with silver nanoparticles

The single-stage synthesis of the conjugates of protein A with silver nanoparticles is performed. The dependence of the dispersity of the prepared sols on the composition of reaction mixture is investigated by optical spectroscopy and transmission electron microscopy. The relative stability of the obtained preparations with respect to the coagulation by NaCl is estimated.

Fluorescent Hard-Sphere Polymer Colloids for Confocal Microscopy

We describe a single-stage synthesis of fluorescent hard-sphere polymer colloids. Monodisperse sterically stabilized poly(methyl methacrylate) spheres were prepared by a dispersion copolymerization of methyl methacrylate and methacrylic acid in the presence of a nonpolymerizable dye. The PMMA colloids are intensely fluorescent and when dispersed in hydrocarbons interact as classical hard spheres. At high concentrations they rapidly nucleate highly ordered three-dimensional colloidal crystals. Four different fluorophores were investigated to minimize the degree of fluorescence photobleaching at λ=488 nm. The dye, 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate (DiIC 18), was observed to photobleach at a significantly slower rate than existing materials (Bosma et al., J. Colloid Interface Sci. 245, 292 (2002); Jardine and Bartlett, Colloid Surf. A, in press). We show the usefulness of the resulting DiIC 18 particles for confocal investigations of colloidal phenomena.

The variation of the equilibrium of chemical reactions in the process of (Bi 2Te 3)(Sb 2Te 3)(Sb 2Se 3) crystal growth

Methods of computation for thermodynamic and differential thermal analysis were used to study the effect of the variation of the chemical equilibrium in the synthesis of (Bi 2Te 3) x (Sb 2Te 3) y (Sb 2Se 3) z ( x+ y+ z=100%) in an ampoule on the characteristics of crystals grown by vertical zone-melting technique. Measurements of thermoelectric characteristics of reference samples were made. The case study of pseudo-binary systems (antimony telluride—antimony selenide, x=0; bismuth telluride—antimony selenide, y=0; bismuth telluride—antimony telluride, z=0) proves the following. As a result of some components turning into a gas–vapour phase, some unreacted original components may be found in a condensed phase. With a single-stage synthesis the products of side reactions of chemical interactions may be formed in the condensed phase. The case study of (Bi 2Te 3) 25(Sb 2Te 3) 72(Sb 2Se 3) 3; (Bi 2Te 3) 70(Sb 2Te 3) 25(Sb 2Se 3) 5; (Bi 2Te 3) 90(Sb 2Te 3) 5(Sb 2Se 3) 5 shows that both the synthesis temperature and the dopants greatly affect the thermodynamic equilibrium between the condensed and gas–vapour phases through the variation of the content of basic components in a condensed phase. On the basis of the performed research, recommendations on the synthesis conditions and crystal growth by zone-melting technique are given.

Single-Step Preparation of Oxide−Oxide Nanocomposites: Chemical Vapor Synthesis of LnAlO3/Al2O3 (Ln = Pr, Nd) Thin Films

Thin films containing nanometer-sized PrAlO3 or NdAlO3 crystals evenly dispersed in an amorphous Al2O3 matrix were grown by chemical vapor deposition (CVD) of heterometal alkoxides, [Ln{Al(OPri)4}3(PriOH)] (Ln = Pr (1), Nd (2)). The lanthanoid to aluminum ratio in the precursors, established by single-crystal X-ray diffraction and chemical analyses of the crystalline products, enables the formation of a stoichiometric 1:1 composite of the general formula LnAlO3/Al2O3 in a single-stage synthesis. The gas-phase thermolysis of 1 and 2 in a cold-wall reactor gave amorphous films of formal composition LnAl3O6, suggesting intact vaporization and decomposition of the heterometal frameworks on the substrates. On-line mass spectral analysis of the gaseous products formed during the CVD process revealed isopropyl alcohol, acetone, propene, and dihydrogen as the main byproducts. The electron spectroscopy for chemical analysis and energy-dispersive X-ray analysis confirmed the film compositions to be LnAl3O6, which w...

Synthesis of tryptamines containing a sulfo group in the benzene ring

It has been shown that sulfophenylhydrazines can be used successfully in a single stage synthesis of tryptamines from arylhydrazines and γ-chlorocarbonyl compounds.

Single stage synthesis of diisopropyl ether – an alternative octane enhancer for lead-free petrol

The title ether was synthesised using a single-pass trickle-bed reactor, over the ion-exchange resin catalyst Amberlyst 15, between 80°C and 140°C and 1 and 70 bar from a feed of propylene and water. Varying contact time experiments showed isopropanol to be the primary product in the reaction and diisopropyl ether the secondary product. In both the liquid and vapour phase, diisopropyl ether is formed by one of the two parallel, competing reactions: from the etherification reaction of isopropanol with propylene or from the dehydrative etherification of isopropanol. Apparent activation energies of 92 and 75 kJ mol −1 were measured for the hydration and etherification reactions, respectively. A linear dependence of rate on pressure was found. The Peng-Robinson–Stryjek-Vera equation of state together with the Wong–Sandler mixing rule was used to model the vapour–liquid behaviour of the system. For highest yield, diisopropyl ether synthesis should take place at high pressure and sufficiently high temperature to overcome the kinetic limitations.

Inverse Chemical Vapor Deposition: A Novel Single Stage Synthesis of Highly Reflective and Conductive Silvered Polymeric Films

Highly reflective and surface conductive flexible polyimide films have been prepared by the incorporation of silver(I) acetate and 1,1,1-trifluoro-2,4-pentanedione into a dimethylacetamide solution of the poly(amic acid) formed from 3,3‘,4,4‘-benzophenone tetracarboxylic acid dianhydride and 4,4‘-oxydianiline. Thermal curing of the silver(I)-containing poly(amic acid) leads to cycloimidization of the polyimide precursor with concomitant silver(I) reduction, yielding a reflective and conductive silver surface approaching that of the native metal. The metalized films retain the essential mechanical and thermal properties of the parent film. Films were characterized by X-ray diffraction, transmission and scanning electron microscopy, tapping mode atomic force microscopy, X-ray photoelectron spectroscopy, and conductivity, reflectivity, thermal, and mechanical measurements.

Single stage synthesis of 2-alkylthio(seleno)-4-hetaryl-3-cyano-5,6,7,8-tetrahydroquinolines

Single stage synthesis of 2-alkylthio(seleno)-4-hetaryl-3-cyano-5,6,7,8-tetrahydroquinolines

Synthesis of bulk SiO2 : MxOy materials in a steady-state laser plume

An analysis was made of the conditions of existence of a two-component steady-state laser plume in atmospheric air. Such a plume is used in single-stage synthesis of bulk molten materials belonging to the SiO2 : MxOy system. Targets of the SiO2 : M type (metal foil and a silica glass rod) and doping elements with boiling points below and above the boiling point of silica glass are discussed. The regimes and efficiency of steady-state transfer of the dopants are considered. The efficiency of transfer of metal oxides during growth of samples with the aid of a cw CO2 laser is reported to be ∼0.05, 0.4, and 0.75g min-1 kW-1 when the mass dopant concentration is ∼8%, 20%, and 60% for the oxides of Ti, Cu, and Ni, respectively.

Acid-catalyzed cyclocondensation of nitriles. III. Synthesis of substituted 3-aminoisoquinolines and study of their cytotoxicity

Earlier, Sereda et al. [I, 2] described the synthesis of 3-aminoisocholines 0II) and the corresponding amidines (II) via an acid-catalyzed cyclocondensation of arylacetonitriles activated by electron-donor substituents in the aromatic nucleus. A simple single-stage synthesis procedure makes these compounds convenient reagents for obtaining various Nfunctional derivatives of isoquinolines, including the alkaloid analogs. Data available in the literature show considerable interest of researchers in compounds of this type, having a substituted amino group in the third position and exhibiting various types of biological activity [3]. In this paper we describe a modified method for the synthesis of substituted 1-methyl3-amino-6,7dimethoxyisoquinolines (see the diagram below) and the results of studying their cytotoxicity. We propose an improved synthetic procedure differing from that described previously [l] by (i) more complete saturation of the reaction mixture with hydrogen chloride prior to the formation of salt I and (ii) by replacing the stages of amidine II transacylation and N-acetylamine Ill hydrolysis by the direct hydrolysis of amidine II to amine III. The improvements were made on the basis of a thorough study of the synthesis; the results will be reported in more detail elsewhere. The synthesis of I-methyl-3-amino-6,7-dimethoxyisoquinoline Ill was carried out in excess acetonitrile without solvent, for the 1:6 ratio of 3,4-dimethoxyphenylacetonitrile to acetonitrile. The reaction mass was saturated with hydrogen chloride until complete formation of the nitrile salt at 12~ The second stage of the cyclization reaction was conducted at 40~ The reaction product, l-methyl3-acetimidoylamino6,7-dimethoxyisoquinoline II, was isolated in the form ofhydrochloride at a yield of 64%, which was converted by hydrolysis into compound Ill at a yield of 56%. Amine llI is a

Preparation of chemically active powders of niobium and titanium oxides and synthesis of dielectric ceramic materials

Lead magnesium niobate (PMN) with additions of lead titanate is a promising material for the manufacturing of multi-layer ceramic capacitors. The present work is devoted to the study of some process approaches making it possible to prepare highly chemically reactive, finely dispersed powders intended for use as starting materials. Such powders make it possible to synthesize PMN by a single-stage process and to obtain powders having a perovskite structure. The proposed processes are based upon the chlorination method for preparing niobium and titanium chemicals. High-purity niobium and titanium oxides were prepared using the following flow-sheet: rectification of niobium pentachloride — condensation — hydrolysis — heat treatment. The granulometric composition of the oxide powders depends on the operational parameters of the powder production processes employed and is variable within the range from 0.5 to 2.0 μm. The lead magnesium niobate (PMN) was produced by single-stage synthesis starting from Nb 2O 5, MgCO 3, PbO and TiO 2 powders and sintered at temperatures ranging from 900 to 1050°C. It was established that the position of the peak of the dielectric constant depends on the pyrochloro-phase concentration and on the titanium-oxide concentration. An industrial process for producing chemically active powders of rare metals oxides intended for subsequent production of ceramic-grade powders and high-technology dielectric materials is proposed.

Lineare Oligophosphaalkane, XXVIII [1] Redox-Cyclisierung funktioneller Methylenbisphosphane XRP-CH2-PRX (X = H, C) mit Cyclopolyphosphanen / Linear Oligophosphaalkanes, XXVIII [1] Redox Cyclization of Functional Methylenebisphosphanes XRP-CH2-PRX (X = H, Cl) with Cyclopolyphosphanes

Reaction of P-H or P-Cl functional methylenebisphosphanes X (R )P - CH2-P(R)X (X = H, Cl; R = Ph, tBu) with cyclopolyphosphanes (R′P)„ (R′ = Ph, tBu, Me; n = 4, 5) affords cyclocarbatetraphosphanes CH2(RP)2(R′P)2 (2-6 ). The cyclopolyphosphanes (R′P)„ em ployed may be synthesized in situ by reaction of chlorophosphanes R′PCl2 with primary phosphanes R′PH2, LiH or magnesium, respectively, providing a single stage synthesis for unsymmetrically substituted cyclocarbatetraphosphanes.

ChemInform Abstract: Single Stage Synthesis of 1,3‐Dihydroxy‐10‐methylacridone.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 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.

Functionalization op saturated hydrocarbons in the presence of aprotic organic superacids. 2. Single-stage synthesis of thioesters R1CO-SR from n-alkanes or cycloalkanes (RH), elemental sulfur, and complexes R1COBr�-2AlBr3

It has been found for the first time that n-alkanes and cycloalkanes (RH) can interact with elemental sulfur at ∼20°C. These reactions go forward in the presence of aprotic organic superacids with the composition R1COBr·2AlBr3, leading to the formation of thioesters R1-CO-SR in satisfactory yields.

Ionenes based on polyvinyl alcohol and the rheological properties of their solutions

A method is proposed for the single-stage synthesis of ionenes based on PVAlc, excluding the formation of the gel fraction, achieved by use of the activating effect of the ammonium groups of the acylating fragment of the esters of haloacetic acids which allows one to dispense with activation through the leaving groups. The quantitative dependence of the reduced viscosity on the concentration satisfactorily observed over a wide concentration interval leading to quite strict determination of the intrinsic viscosity of the polyionenes has been established.

ChemInform Abstract: Investigation of the Single‐Stage Synthesis of 8‐Hydroxyquinoline.

ChemInform Abstract: Investigation of the Single‐Stage Synthesis of 8‐Hydroxyquinoline.

Condensation of carbazole with acetone in the presence of trifluoroacetic anhydride. A single stage synthesis of 1,1,3-trimethyl-1H-pyrido[j,k]carbazole

1,1,3-Trimethyl-iH-pyrido[j,k]carbaz01e. Trifluoroacetic anhydride (20 ml, 143 mmole) was added slowly (I0 h) with stirring to a solution of carbazole (5 g, 30 mmole) in acetone (90 m_l, 1.4 mole) and the stirring continued for a further 10-12 h. The product was diluted with benzene (20 ml), washed with water (3 x 300 ml), the organic layer .removed and dried with CaCI2. The solvent was distilled off and the oily residue dissolved in heptane (7 ml) and theproduct mixture separated on an A120s column (3 • 60 Cmo activity II) using heptane as eluent, l,l,3-Trimethyl-iH-pyrido[j,k]carbazole (3.6 g, 66%) was obtained with mp 113i14.5~ (from heptane) and Rf 0~ (benzene:hexane i:i), IR Spectrum (Nujol): 1620, 1590 (C-C), 835, 755 cm -~ (C--H). It was strongly triboluminescent in the visible region. PMR Spectrum (CCl~): 1.70 (6H, s, I-CH3), 2~ (3H, s, 3-CH3), 5.22 (kH, s, =CH), 6.8-7.3 (4H, m, 5-, 8-, 9-, and 10-H), 7.55 (1H, d, J~5 = 7 Hz, 4-H), 7.65 (IH, d, JTe = 7 Hz, 7-}I), 7~ ppm (IH, d, Js6 = 7 Hz, 6-H) o

Copolymerization of styrene with some oxiranes initiated by KC 24

The copolymerizations of styrene (St) with ethylene oxide (EO), propylene oxide (PO) and butylene oxide (BO) initiated by the graphite intercalation compound KC 24 are studied. The possibility to obtain block copolymers in a single stage synthesis is shown. It is established that, in the initial stages of the copolymerization (St: EO = 1, 20°, yields < 30%) the products contain over 90% of St-units. At higher conversions (yields about 80%), the copolymers contain 60–70% of St-units and the molecular weight distribution is monomodal. The influences of the ratio of comonomers and the temperature of copolymerization on the composition and the molecular weight distribution of the copolymers are also studied. The copolymerizations of St with PO and BO give yields below 30%. Considerable quantities of homopolymers are formed along with the high molecular fractions, rich in St.