Yields Of Reaction Products Research Articles

Synthesis of n-acetylglucosaminides dimers

Glycosylation of aliphatic and aromatic α,ω-diols by the oxazoline method and by peracetylated α-D-glucosaminylchloride in the presence of zinc chloride and co-promoters (quaternary ammonium salts or trityl chloride) have been investigated. The highest yield of bis-glucosaminides in the conditions of oxazoline synthesis (the solvent is dichloroethane, the temperature of the reaction mixture is ~100°C, catalytic quantities of p-toluenesulfonic acid) has been observed for octane-1,8-diol. The products of monoglycosylation of butane-1,4-diol and dodecane-1,12-diol have been also obtained. The influence of the nature of a со-promoter has been studied on the model glycosylation reaction of octane-1,8-diol with peracetylated α-D-glucosaminylchloride in reflux dichloromethane (the ratio of glycosyl-acceptor : glycosyl-donor : zinc chloride : quaternary ammonium salt = 1 : 2,5 : 2,5 : 2,5). The best yields of dimeric glycoside have been obtained using tetrabutylammonium bromide. Increase of the amount of zinc chloride up to 1.5 equivalents in relation to the glycosyl donor has not led to significant changes of the reaction product yield. The yields of bis-glycosylation have been increased using peracetylated α-D-glucosaminylchloride as a glycosyl-donor for all aglycones. The corresponding mono- and bis-glucosaminides of 2,2’-(1,2-phenylenedioxy)diethanole have been synthesized by glycosylation in these conditions. The structure of the glycosides synthesized has been proven by 1H-NMR-spectroscopy.

Sequential Chelation-Assisted Aromatic C–H Functionalisation via Catalytic meta Sulfonation

The sequential functionalisation of 2-phenylpyridine is presented using selective ortho- and meta-directing processes. It was found that performing a reaction sequence with meta functionalisation first followed by ortho functionalisation provided novel reaction products in good yields and with complete regioselectivity.

ChemInform Abstract: Ruthenium‐Catalyzed Transfer Hydrogenation of Nitriles: Reduction and Subsequent N‐Monoalkylation to Secondary Amines.

AbstractOther secondary alcohols (2‐butanol, 2‐pentanol) can substitute isopropanol to afford the corresponding reaction products in good yields while ethanol affords the products only in low yields.

Mo+TiO2(110) Mixed Oxide Layer: Structure and Reactivity

We present a STM/XPS/TPD/LEED study of the structural and electronic properties of Mo+Ti mixed oxide layers on TiO2(110), and of their interaction with water, methanol and ethanol. Several different preparation procedures were tested and layers with different degrees of Mo/Ti mixing were prepared. Ordered mixed oxide surface phases with distinct LEED patterns could not be found; for all investigated Mo concentrations a TiO2(110) like pattern was observed. Mo tends to agglomerate on the surface where it is found predominantly as Mo6+ at low coverages and as Mo4+ at high coverages. Mo4+ was also identified in the bulk of the mixed oxide layer. The Mo3d binding energies categorize the Mo4+ species as being dimeric. A third Mo3d doublet is attributed to a Mo species (Mon+) with an oxidation state between those reported for Mo in MoO2 and metallic Mo. Two types of Mo-induced features could be identified in the STM images for low Mo concentrations (in the range of 1 %). At higher Mo concentrations (~50 %) the surface is characterized by stripes with limited lengths in [001] direction. The concentration of bridging oxygen vacancies, which are common defects on TiO2(110), is reduced significantly even at low Mo concentrations. Methanol and ethanol TPD spectra reflect this effect by a decrease of the intensity of the features related to these surface defects. At elevated MoOx coverages, the yield of reaction products in methanol and ethanol TPD spectra are somewhat smaller than those found for clean TiO2(110) and the reactions occur at lower temperature.

Transformation of Trichloroethylene to Predominantly Non‐Regulated Products under Stimulated Sulfate Reducing Conditions

AbstractAnaerobic microcosms containing sediment and water were amended to generate a range of mass loadings of FeS. Microcosms were then spiked with trichloroethylene (TCE) and the concentration of TCE and possible volatile reaction products monitored over time. The lowest yields of TCE, as well as the lowest yields of reaction products regulated under the Safe Drinking Water Act (i.e., dichloroethylene isomers and vinyl chloride), were observed at FeS mass loadings at or above 20 g/L. Sixty eight days after spiking with TCE, selected microcosms were amended with sulfate and lactate, or sulfate, Fe(II), and lactate, and the effect of these amendments on TCE transformation and yield of regulated products was compared to microcosms that did not receive any amendments. Addition of sulfate, Fe(II), and lactate led to the greatest improvement on TCE depletion rates and the lowest yields of regulated reaction products compared with addition of sulfate and lactate, or no amendments. Analysis of kinetic modeling suggests that microbial and abiotic processes acted in concert to promote TCE transformation to a relatively low yield of regulated products in microbially active microcosms that contained high mass loadings of FeS.

ChemInform Abstract: Asymmetric Hydrogenation of α,α′‐Disubstituted Cycloketones Through Dynamic Kinetic Resolution: An Efficient Construction of Chiral Diols with Three Contiguous Stereocenters.

AbstractThis method uses catalyst loadings as low as 0.1 mol% and yields (cis,cis)‐reaction products in good yields and with high enantio‐ and diastereoselectivities.

Specific features of phase transfer catalytic glycosylation of aromatic hydroxy acids

The catalytic phase transfer reactions of per acetylated alpha-D-glucosaminyl chloride with isomeric hydroxybenzoic, 1-hydroxy-2-naphthoic acids in solid potassium carbonate--acetonitrile were studied. It was found that the composition and yields of reaction products are determined by the nature of the source ofcarboxylic acids, lipophilic phase transfer catalyst, temperature. For the first time found that the O-beta-glycosyl esters of ortho-hydroxyaromatic acids in the presence of potassium carbonate can anomerizovatsya in 1,2-cis derivatives. The structure of the synthesized compounds proved 1H NMR spectroscopy. In in vivo experiments it was established that glycosyl esters of salicylic acid and per acetylated 2-carboxy phenylglucosaminide exhibit analgesic activity similar to aspirin.

Hydrogenation of phenols in ionic liquids on rhodium nanoparticles

A new catalyst system based on rhodium nanoparticles stabilized by polyacrylic acid have been suggested for the hydrogenation of phenols in ionic liquids. It has been shown that high near-quantitative yields of reaction products are achieved in ionic liquids containing a tetraalkylammonium cation. By the TEM and XPS techniques it has been revealed that the use of ionic liquids substantially decreases the particle size and reduces the aggregation of nanoparticles through the inclusion of the ionic liquid cations into the surface layer along with polyacrylic acid.

Influence of Different Catalysts and Solvents on the General Base Catalytical Esterification of Polyoxyethylene Sorbitan Trioleate with Maleic Anhydride and Styrene-Co-Maleic Anhydride

<p>The general base catalitycal esterification of Polyoxyethylene sorbitane Trioleate with maleic anhydride (Ma) and styrene-co-maleic anhydride (Sma) using pyridine as catalyst is described. We investigated the effect of different factors on the yield of reaction product. The analysis of the effect of different factors<br /> on the process of catalytical esterification showed that the catalysts and solvents can be arranged by their activity in the following order: sulfuric acid > toluene sulfonic acid > triethylamine > pyridine > without a catalyst and dimethylsulfoxide (DMSO) > O-xylene > dimethylformamide (DMF), respectively. It should be noted that pyridine to its activity is not significantly inferior to the traditional catalysts and with DMSO using the yield of product is increasing. It is concluded that the reaction proceeds by 2nd order. It was found that decreasing the temperature of reaction to a lower temperature, where there is an intensive incubation period, leads to decreasing of yield of polyesters. The rate constant and activation energy were calculated. It was found that the process occurred on 98% at 130 °С and 80 min for PoesTo/Ma and on 88% at 150 °С and 40 min for PoesTo/Sma. For preparation of reaction product to analysis new methods were developed. It was shown, that on <sup>1</sup>H and <sup>13</sup>C spectra an overlap of the individual peaks or their close concentration in one area is observed, which makes it not possible to complete the analysis of the spectra. <sup>1</sup>H and <sup>13</sup>C spectra give a preliminary idea of the structure of the reaction products. It is concluded that 2-D NMR measurements more useful for further confirming of structure of PoesTo/Ma and PoesTo/Sma. HLB shown that we obtained two different surfactants where by catalytical esterification the hydrophilic part of Tween in PoesTo/Ma and the lipophilic part in PoesTo/Sma was increased.</p>

One-Pot Process of Anthraquinone Synthesis in the Presence of Mo-V-P Heteropoly Acid Solutions as a Bifunctional Catalysts

Acid-catalytic 1,3-butadiene condensation with para-quinones followed by the obtained product oxidation may be performed in one stage as one-pot process, if assisted by the aqueous solutions of Mo-V-P heteropoly acids with a composition of HaPzMoyVxOb. 1,4-naphthoquinone condensation with 1,3-butadiene in the HPA solutions with no organic solvents yields 9,10-anthraquinone (AQ) mixed with tetrahydro-AQ (THA) and dihydro-AQ (DHA). However, AQ yield and its purity may be considerably improved by using water-mixable organic solvents, e.g., acetone, 1,4-dioxane, as well as high vanadium content HPA such as H15P4Mo18V7O89 and H17P3Mo16V10O89. Process optimization provides 70% yield of reaction product containing no less than 90% AQ.

Effect of variable composition of the gas phase on the degree of conversion in gas–solid topochemical reactions

The paper analyzes the potential yield of reaction products or the degree of conversion in a gas– solid system. Dependences of the degree of conversion for the solid phase on gas composition for various types of reactions are presented. They are used to assess the reactivity of the system. The data may be used in planning and implementation of respective processes.

Reactions of O,O-dialkyldithiophosphoric acids with non-activated α-olefins

Electrophilic addition reactions of O,O-dialkyldithiophosphoric acids to non-activated α-olefins proceeding in accordance with the Markovnikov’s rule were studied. In the absence of a catalyst these reactions occur very slowly to give the products in low yields, while Lewis acid as a catalyst can greatly accelerate the reaction and increase the conversion in the AdE-processes. A similar acceleration of the addition processes and an increase in the reaction product yield occur at the action of ultrasound on the reaction medium.

Two Different Hydrogen Bond Donor Ligands Together: A Selectivity Improvement in Organometallic {Re(CO)3} Anion Hosts

Rhenium(I) compounds [Re(CO)(3)(Hdmpz)(2)(ampy)]BAr'(4) and [Re(CO)(3)(N-MeIm)(2)(ampy)]BAr'(4) (Hdmpz = 3,5-dimethylpyrazole, N-MeIm = N-methylimidazole, ampy = 2-aminopyridine or 3-aminopyridine) have been prepared stepwise as the sole reaction products in good yields. The cationic complexes feature two different types of hydrogen bond donor ligands, and their anion binding behavior has been studied both in solution and in the solid state. Compounds with 2-ampy ligands are labile in the presence of nearly all of the anions tested. The X-ray structure of the complex [Re(CO)(3)(Hdmpz)(2)(ampy)](+) (2) shows that the 2-ampy ligand is metal-coordinated through the amino group, a fact that can be responsible for its labile character. The 3-ampy derivatives (coordinated through the pyridinic nitrogen atom) are stable toward the addition of several anions and are more selective anion hosts than their tris(pyrazole) or tris(imidazole) counterparts. This selectivity is higher for compound [Re(CO)(3)(N-MeIm)(2)(MeNA)]BAr'(4) (5·BAr'(4), MeNA = N-methylnicotinamide) that features an amido moiety, which is a better hydrogen bond donor than the amino group. Some of the receptor-anion adducts have been characterized in the solid state by X-ray diffraction, showing that both types of hydrogen bond donor ligands of the cationic receptor participate in the interaction with the anion hosts. DFT calculations suggest that coordination of the ampy ligands is more favorable through the amino group only for the cationic complex 2, as a consequence of the existence of a strong intramolecular hydrogen bond. In all other cases, the pyridinic coordination is clearly favored.

Synthesis of higher spiroacetals by condensation of alkyl- and cycloalkylcyclopentanones and cyclohexanones with dihydric alcohols in the presence of heterogenic catalysts

The condensation of C3-C7 alkyl- and cycloalkylcyclopentanones and cyclohexanones with 1,2-ethane-, 1,2-propane-, and 1,3-butanediols in the presence of heterogenic acid catalysts provided new representatives of spiroacetals. The highest yields of reaction products were obtained in the presence of phosphomolybdic heteropolyacid additionally modified with cobalt and bromine, and also in the presence of the chlorinated cationite KU-23 at 110–130°C. The synthesized spiroacetals possess the jasmine and menthol-wooden fragrance of various tinges.

On the Regioselectivity of the Intramolecular [2 + 2]-Photocycloaddition of Alk-3-enyl Tetronates

The simple diastereoselectivity and the regioselectivity of the [2 + 2]-photocycloaddition of alk-3-enyl tetronates were studied, depending on the nature of the substituent R in the α-position. Fourteen tetronates were synthesized and their intramolecular photocycloaddition reactions performed. If R was an alkoxycarbonyl group and if the olefin, which underwent the intramolecular addition, was sterically congested, crossed photoproducts prevailed and were formed in yields between 35 and 65%. In all other cases, the straight photoproducts were obtained as the main reaction products in yields ranging from 39 to 84%. The structures of the photochemical products were thoroughly investigated by one- and two-dimensional NMR experiments. In all cases, the diastereoselectivitiy was excellent and only a single diastereoisomer was formed. A mechanistic model is proposed, which explains the regioselectivity of the [2 + 2]-photocycloaddition reaction.

Comparative Study of Solid-Phase Extraction and Liquid−Liquid Extraction for the Reliable Quantification of High Value Added Compounds from Oxidation Processes of Wood-Derived Lignin

Technologies and processes for lignocellulosic conversion in biorefineries are emergent subjects of research for which a reliable analysis of raw materials and quantification of yields of reaction products are required. This paper presents the development of an analytical method, using solid-phase extraction (SPE), for application to the reaction mixture of the oxidation of wood-derived lignin. The aim of the method is to extract the high value added aldehydes for quantification by high-performance liquid chromatography with ultraviolet detection (HPLC-UV). SPE and conventional liquid−liquid extraction (LLE) were evaluated and compared concerning recoveries and precision: (i) solutions of standard phenolic compounds (in alkaline medium and in lignin as matrix) and (ii) real samples and spiked real samples. The presence of lignin in the solutions decreases the recoveries of compounds from about 100% (no lignin) to 91% (for prepared solutions of lignin) and 94% (for real samples). This decrease was clearly evident with the increase of concentration of phenolic compounds in spiked real samples. The recovery averages and precision of SPE were higher than those of LLE and less affected by the presence of lignin. The results gathered and discussed in this work revealed SPE as an alternative to LLE: it is less time-consuming and has higher accuracy and precision for the quantification of phenolic compounds as reaction products of lignin oxidation.

The simulation of a gas-liquid chemical reactor with dispersed medium

It is suggested to develop a gas-liquid reactor in which heterogeneous exothermal reactions will proceed, with cumene selected as fuel. The temperature field and the yield of reaction product are given as functions of flow rate and initial temperature of mixture. The case is considered of the mass content of fuel components, at which the detonation occurs. Calculation is preformed of the cooling system for preventing the ignition and maintaining the temperature conditions of reaction. The calculation of chemical reaction is performed in the approximation of model of eddy dissipation which is valid at high values of Reynolds number.

Influence of process parameters on the hydrothermal decomposition and oxidation of glucose in sub- and supercritical water

Supercritical water oxidation (SCWO) of wet waste biomass for energy recovery could be an advantageous alternative to conventional combustion with preceding drying. Therefore the reactions of glucose as a model substance for cellulosic biomass were investigated in sub- and supercritical water. The results of hydrothermal and oxidative experiments carried out in a continuous high-pressure plant with a feed solution of 0.2–1.2% (g g −1) glucose at 24–34 MPa, 250–480 °C and residence times of 2–35 s are presented. In the presence of a stoichiometric oxygen concentration (for total oxidation to carbon dioxide and water) glucose decomposes already at subcritical temperatures readily to carbon monoxide and low molecular liquid substances, chiefly organic acids like e.g. acetic acid and glycolic acid. In turn these are in general more stable and react only slowly with oxygen. The effect of temperature, residence time, pressure, reactant concentration and addition of zinc sulfate on the conversion and the yields of reaction products was demonstrated. Already at 350 °C (24 MPa and 30 s) 99% of the glucose are converted. With increasing temperature the production of CO 2 increases. However, even at 480 °C (34 MPa and 4 s) significant amounts of CO are formed and the reaction of glucose to CO 2 and H 2O is not complete. Higher temperatures or greatly longer residence times are needed for a total combustion of the glucose.

ChemInform Abstract: Are Microreactors Useful for Organic Synthesis?

Recent developments regarding microreactors of which reaction volume is at μl order are reviewed from the viewpoint of system design for laboratory automation which is useful for process chemistry. Physical and chemical phenomena at μm level (size effects), structural elements, and fabrication methods concerning microreactors are summarized. Applied reaction examples classified into seven categories are also surveyed. The advantages of microreactors are (1) easy of rapid and precise control of temperature, which is helpful in obtaining of heat-unstable compounds, (2) high reaction rate, (3) high yield of reaction products (the author's hypothesis) and (4) easy of scale-up of reaction volume without complicated calculations in chemical engineering. The productivity of chemical compounds by microreactors is much enough for cost-effective fine chemicals. The importance of combination of computer-aided synthesis design and microreactors is also pointed out to swiftly validate the candidate reaction routes presented. In conclusion, microreactors have great potential for serving as a powerful tool for organic synthesis research.

A Magnetic Multi-Purpose Organocatalyst

The straightforward synthesis of magnetic nanoparticle-supported glutathione 1 and its use as ”organocatalyst" is reported. The immobilized and reusable catalyst 1 proved to be active in a number of different reactions. The Paal-Knorr pyrrole synthesis, aza-Michael reaction, and pyrazole synthesis were carried out in water as ­reaction medium under microwave irradiation, providing the reaction products in high yields after short reaction times.