Effective Reaction Medium Research Articles

A domino synthetic approach for new, angular pyrazol- and isoxazol-heterocycles using [DBU][Ac] as an effective reaction medium

Some new, angular pyrazol- and isoxazol-heterocycles have been synthesized by the reaction of pyrazolone/isoxazolone with typical ketone-based substrates—O-alkenyloxy/alkynyloxy-acetophenones.

Multiphase reaction media involving water and carbon dioxide for selective hydrogenation

The features of multiphase reaction media using water (bulk water, supported thin aqueous phase) and dense phase carbon dioxide are reviewed for selective hydrogenation of carbonyl, nitro, and cyano compounds. The interface of aqueous and organic phases is important in determining the rate of hydrogenation and the product selectivity. For supported aqueous phase catalysts, the interface between the thin aqueous film and a support material (for example, porous silica gel) has also an influential impact. The pressurization of a liquid reaction mixture (organic and/or aqueous phases) with carbon dioxide shows interesting positive effects on the reaction rate, the product selectivity, and the deactivation of a conventional supported metal catalyst. In some cases the use of both water and dense phase carbon dioxide serves as an effective reaction medium. In other words, these green solvents may act as reaction promoters. Possible roles of their actions are discussed.

Synthesis of cellulose-2,3-bis(3,5-dimethylphenylcarbamate) in an ionic liquid and its chiral separation efficiency as stationary phase.

A chiral selector of cellulose-2,3-bis(3,5-dimethylphenylcarbamate) (CBDMPC) was synthesized by reacting 3,5-dimethylphenyl isocyanate with microcrystalline cellulose dissolved in an ionic liquid of 1-allyl-3-methyl-imidazolium chloride (AMIMCl). The obtained chiral selector was effectively characterized by infrared spectroscopy, elemental analysis and 1H NMR. The selector was reacted with 3-aminopropylsilanized silica gel and the CBDMPC bonded chiral stationary phase (CSP) was obtained. Chromatographic evaluation of the prepared CSPs was conducted by high performance liquid chromatographic (HPLC) and baseline separation of three typical fungicides including hexaconazole, metalaxyl and myclobutanil was achieved using n-hexane/isopropanol as the mobile phase with a flow rate 1.0 mL/min. Experimental results also showed that AMIMCl could be recycled easily and reused in the preparation of CSPs as an effective reaction media.

ChemInform Abstract: A Novel Method for the Synthesis of Spiro[indoline‐pyrazolo[4′,3′:5,6]pyrido[2,3‐d]pyrimidine]triones by Alum as a Reusable Catalyst.

AbstractTitle compounds (IV) are efficiently synthesized through a three‐component one‐pot reaction using [bmim]PF6 as an effective green reaction medium.

Novel N-methylimidazolium chiral ionic liquids with esterfunction functionality in cation

Using (S)-(-)-2-chloropropionic acid ethyl ester and N-methylimidazole as raw materials, we designed and synthesized three N-methylimidazolium chiral ionic liquids by the nucleophilic substitution reaction or anion exchange reaction. These chiral ionic liquids structures were analyzed with structure optimization calculation, IR, and HNMR. Their reaction mechanism and physical chemistry properties were explored. As a result, these chiral ionic liquids possess optical activity, low melting point, high conductivity, and weak acidity, etc. They can serve as effective reaction media as well as chiral catalysts. They are presently being investigated as dispersion agent in molecular imprinting ployer in our laboratory.

A facile and efficient [bmim]N3 catalyzed direct oxidative esterification of arylaldehydes with alcohols

Abstract Task-specific ionic liquid, [bmim]N 3 was used as an effective catalyst and reaction medium for the direct oxidative esterification of arylaldehydes with alcohols. The oxidative esterification reaction of a variety of arylaldehydes took place smoothly with some primary and secondary alcohols in [bmim]N 3 . Satisfactory results were obtained with arylaldehydes containing electron withdrawing groups. Tertiary alcohols did not react under these conditions.

ChemInform Abstract: Catalyst‐Free Synthesis of Quinazoline Derivatives Using Low Melting Sugar—Urea—Salt Mixture as a Solvent.

Low melting mixture of maltose–dimethylurea (DMU)–NH4Cl was found to be an inexpensive, non-toxic, easily biodegradable and effective reaction medium in the catalyst-free synthesis of quinazoline derivatives. This simple and efficient method furnished the corresponding quinazolines in high yields via one-pot three-component reaction of 2-aminoaryl ketones, aldehyde, and ammonium acetate under aerobic oxidation conditions.

Direct liquefaction of Dunaliella tertiolecta for bio-oil in sub/supercritical ethanol–water

This paper presents bio-oil preparation by direct liquefaction of Dunaliella tertiolecta (D. tertiolecta) with sub/supercritical ethanol–water as the medium in a batch autoclave with high temperature and high pressure. The results indicated that ethanol and water showed synergistic effects on direct liquefaction of D. tertiolecta. The maximum bio-oil yield was 64.68%, with an optimal D. tertiolecta conversion of 98.24% in sub/supercritical ethanol–water. The detailed chemical compositional analysis of the bio-oil was performed using an EA, FT-IR, and GC–MS. The empirical formulas of the bio-oil obtained using the ethanol–water co-solvent (40%, v/v) and sole water as the reaction medium were CH1.52O0.14N0.06 and CH1.43O0.23N0.09, with calorific values of 34.96 and 29.80MJkg−1, respectively. XPS and SEM results showed that ethanol–water is a very effective reaction medium in the liquefaction. A plausible reaction mechanism of the main chemical component in D. tertiolecta is proposed based on our results and the literatures.

Michael addition kinetics of ethyl acetoacetate and 2-ethylhexyl acrylate in ionic liquids

The Michael addition is one of the most common and versatile methods for making carbon–carbon bonds, however little is known about the potential of utilizing ionic liquids as solvents in these reactions. Initial work from our laboratory is presented, showing that model imidazolium- and phosphonium-based ionic liquid solvents can be used as effective reaction media in the Michael addition. Kinetic data are also reported and the results indicate that the use of ionic liquids as reaction media resulted in an observed rate enhancement when compared with more common organic solvents such as toluene, THF, and DMF. Observed rates were comparable to those observed in DMSO.

Catalyst-free synthesis of quinazoline derivatives using low melting sugar–urea–salt mixture as a solvent

Low melting mixture of maltose–dimethylurea (DMU)–NH4Cl was found to be an inexpensive, non-toxic, easily biodegradable and effective reaction medium in the catalyst-free synthesis of quinazoline derivatives. This simple and efficient method furnished the corresponding quinazolines in high yields via one-pot three-component reaction of 2-aminoaryl ketones, aldehyde, and ammonium acetate under aerobic oxidation conditions.

Homogeneous epoxidation of lipophilic alkenes by aqueous hydrogen peroxide: catalysis of a Keggin-type phosphotungstate-functionalized ionic liquid in amphipathic ionic liquid solution

The ionic liquid compositions (ILC) composed of the Keggin-type phosphotungstate-functionalized ionic liquid of [Dopy]3[PW12O40] (1) and the amphipathic IL mixture of [Bpy]BF4 and [Dopy]BF4, were constructed as an effective catalytic system and ideal reaction medium for alkene epoxidation by aqueous H2O2, in which the real homogeneous catalysis was fulfilled with advantages of high activity, simplified work-up and available recyclability. The designing concept of the ILC and the IL effect on the activity/stability were discussed herein.

Thermal isomerization of [formula omitted]-pinene in supercritical ethanol

The experimental study followed by mathematical processing of the data showed that supercritical ethanol is an effective reaction medium for thermal isomerization of α -pinene. Rate of the reaction in supercritical solvent is by several orders of magnitude greater than the rate observed under normal conditions, with selectivity to the target reaction products being retained. The study allowed us for the first time to obtain the kinetic model of α -pinene isomerization in supercritical ethanol that takes into account temperature and pressure effect on the reaction rate and selectivity.

Design and synthesis of fused-ring chiral ionic liquids from amino acid derivatives

Six novel imidazolium salts, which contain a chiral moiety as well as a fused-ring system, have been designed, synthesized, and fully characterized. The synthesis of these ionic liquids is concise and practical due to the commercial availability of the starting materials. These imidazolium compounds were readily prepared from 1-methyl-2-imidazoliumcarboxaldehyde and chiral amino alcohols. Salts that contain the PF 6 anion were solids, but salts with the NTf 2 anion were liquids at room temperature. We envision that these new chiral imidazolium compounds can serve as effective reaction media as well as chiral catalysts for asymmetric reactions, which are presently being investigated in our lab.

Design and Synthesis of Pyridinium Chiral Ionic Liquids Tethered to a Urea Functionality

Nine chiral room-temperature ionic liquids (RTILs), which contain a chiral moiety and a urea functionality bonded to a pyridinium ring, have been designed and synthesized. The synthesis of these ionic liquids is concise and practical due to the commercial availability of the starting materials. These novel RTILs were readily prepared from 2-(aminomethyl)pyridine and amino acid ester derived isocyanates. We envision that these new chiral RTILs can serve as effective reaction media as well as chiral catalysts for asymmetric reactions, which are presently being investigated in our laboratory.

Novel imidazolium chiral ionic liquids that contain a urea functionality

Nine chiral room temperature ionic liquids (RTILs), which contain a chiral moiety and a urea functionality bonded to a imidazolium ring, have been designed and synthesized. The synthesis of these ionic liquids is concise and practical due to the commercial availability of the starting materials. These novel RTILs were readily prepared from 1-(3-aminopropyl)imidazole and amino acid ester derived isocyanates. We envision that these new chiral RTILs can serve as effective reaction media as well as chiral catalysts, which are presently being investigated in our laboratory.

Oxidation of Alcohols to Carbonyl Compounds with CrO3·SiO2 in Supercritical Carbon Dioxide

Supercritical carbon dioxide (scCO2) is an effective reaction medium to perform the oxidation of primary and secondary aliphatic alcohols to the corresponding carbonyl compounds with chromium trioxide supported on silica. These reactions were performed by flowing a solution of the alcohol in scCO2 through a column containing the supported reagent and recovering the product by depressurization. This method avoids the use of organic solvents and the contamination of the products with chromium species.

Efficient and Eco‐Friendly Process for the Synthesis of N‐Substituted 4‐Methylene‐2‐oxazolidinones in Ionic Liquids.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Efficient and eco-friendly process for the synthesis of N-substituted 4-methylene-2-oxazolidinones in ionic liquids

The carbonylation of amines with propargylic alcohol using CO 2 as carbonyl source to yield N-substituted 4-methylene-2-oxazolidinones could efficiently proceed in ionic liquids, and various 4-methylene oxazolidinones with high yields could be obtained under relatively mild conditions. This result showed that ionic liquid might be an effective catalyst and reaction medium for the activation of CO 2, which also offered a new way to the chemical fixation of CO 2.

Unusual Cyclopropanation of 9-Bromocamphor Derivatives: A Novel Formal C(1)−C(7) Bond Cleavage of Camphor

[reaction: see text] An unusual cyclopropanation of 9-bromocamphor derivatives 1 to a 7-spiro-cyclopropyl camphor derivative 3 was effected by the action of potassium tert-butoxide (or sodium hydride) in warm DMSO. The exo-hydroxy group and a non-hydrogen endo-substituent at C(2) have proven to be essential structural elements, and the solvent DMSO has proven to be the sole effective reaction medium. Tricyclic compound 3 undergoes a facile tandem Wagner-Meerwein rearrangement-cyclopropyl ring-opening under mild acidic conditions, leading to norbornenyl derivative 12 and subsequent Meinwald rearrangement of bicyclic epoxide 13 to a formal C(1)-C(7) bond cleavage product 14.

Optimisation of the operation variables of a supercritical water oxidation process

The unique physical-chemical properties of water above its critical point (374.2°C and 22.1 MPa) makes supercritical water (SCW) an effective reaction medium for oxidation of organic compounds. Gases and many organic compounds are miscible in SCW, so reaction between oxygen and waste is carried out without interface transport constraints. Supercritical water oxidation (SCWO) can give high destruction efficiencies for a wide variety of hazardous wastes, at low reactor residence times. To study the SCWO, experiments were carried out in a pilot plant equipped with a pressure shell and cooled wall reactor. Effect of operation variables: oxidant excess, reaction temperature and residence time, is studied in order to optimise the contaminant removal efficiency. Aqueous solutions of isopropyl alcohol were used as feed. No effect of air excess and residence time higher than 1 minute on removal efficiency was found, so exclusive dependence of temperature is concluded. Whereas temperature is above 650°C, reactor can work in a wide range of operation conditions with destruction efficiency over 99%. In addition, operation at optimal conditions is reported, using 10%(w) isopropyl alcohol – 1%(w) aniline as feed. Removal efficiencies higher than 99.9% and nitrite-nitrate concentrations less than 10 ppm were obtained.