Alcohols In Supercritical Carbon Dioxide Research Articles

Binary Diffusion Coefficients for Short Chain Alcohols in Supercritical Carbon Dioxide—Experimental and Predictive Correlations

Experimental binary diffusion coefficients for short-chain alcohols in supercritical carbon dioxide were measured using the Taylor dispersion technique in a temperature range of 306.15 K to 331.15 K and along the 10.5 MPa isobar. The obtained diffusion coefficients were in the order of 10-8 m2 s-1. The dependence of D on temperature and solvent density was examined together with the influence of molecular size. Some classic correlation models based on the hydrodynamic and free volume theory were used to estimate the diffusion coefficients in supercritical carbon dioxide. Predicted values were generally overestimated in comparison with experimental ones and correlations were shown to be valid only in high-density regions.

Adaptive Process Optimization for Continuous Methylation of Alcohols in Supercritical Carbon Dioxide

A self-optimizing continuous flow reactor has been developed using the Super-Modified Simplex algorithm. This system, coupled with online gas chromatographic analysis enables automated optimization...

ChemInform Abstract: Effective Guanidine‐Catalyzed Synthesis of Carbonate and Carbamate Derivatives from Propargyl Alcohols in Supercritical Carbon Dioxide

Abstractall yields determined by GC

Effective Guanidine‐Catalyzed Synthesis of Carbonate and Carbamate Derivatives from Propargyl Alcohols in Supercritical Carbon Dioxide

AbstractThe reactions of propargyl alcohols with carbon dioxide in supercritical carbon dioxide or in acetonitrile with gaseous carbon dioxide in the presence of organic bases as catalysts have been examined. Bicyclic guanidines are effective catalysts for the formation of α‐methylene cyclic carbonates under mild reaction conditions. Oxoalkyl carbonates, oxoalkyl carbamates or α‐methyleneoxazolidinones are obtained in high yields and good selectivities in one‐step starting from propargyl alcohols and an external nucleophile (alcohols or amines) using bicyclic guanidines as catalysts in supercritical carbon dioxide. Propargylic diols under the same reaction conditions underwent a rearrangement process instead of carbon dioxide insertion whereas in the presence of an external nucleophile the formation of oxocarbonates, oxocarbamates or cyclic carbamates was achieved in satisfactory yields.

Phase equilibria of alcohols in supercritical fluids Part II. The effect of side branching on C 8 alcohols in supercritical carbon dioxide

This paper is a continuation of a previous study and investigated the phase equilibria of six C 8 alcohols (2,2,4-trimethyl-1-pentanol, 2,4,4-trimethyl-1-pentanol, 2-ethyl-1-hexanol, 2-propyl-1-pentanol, 4-methyl-3-heptanol and 6-methyl-2-heptanol) in supercritical carbon dioxide. Data has been measured between 308 and 348 K for alcohol mass fractions between 0.660 and 0.0162. The results show that the position, size and quantity of side chains have a significant effect on the phase behaviour by changing the shape of the molecule and the effect of the hydroxyl group on the polarity of the molecule. The pressure required for total solubility increases in the following sequence: 4-methyl-3-heptanol < 2,2,4-trimethyl-1-pentanol < 6-methyl-2-heptanol < 2,4,4-trimethyl-1-pentanol < 2-propyl-1-pentanol < 2-ethyl-1-hexanol < 1-octanol. The difference in phase behaviour is believed to be a result of a difference in shielding of the hydroxyl group. Greater shielding of the hydroxyl group results in a less asymmetric system, and this, in turn, results in higher solubility of the molecule.

Calculation of the solid solubilities in supercritical carbon dioxide using a new G ex mixing rule

The aim of this study is to develop a new EOS/G ex-type mixing rule with special attention to calculating the solid solubilities of aromatic hydrocarbons, aliphatic carboxylic acids, aromatic acids, and heavy aliphatic and aromatic alcohols in supercritical carbon dioxide. A volume correction term is applied with a combination of second and third virial coefficients which the equation for the third virial coefficient is quadratic, according to the suggestion by Hall and Iglesias-Silva. In this study, the cubic Peng–Robinson (PR) and Soave–Redlich–Kwong (SRK) equations of state have been used to calculate the solid solubilities of 23 solutes in supercritical CO 2, by using six mixing rules, namely, the Wong–Sandler (WS) rule, the Orbey–Sandler (OS) rule, the van der Waals one fluid rule with one (VDW1) and two (VDW2) adjustable parameters, the covolume dependent (CVD) rule and the new mixing rule. In all cases, the NRTL model was chosen as the excess Gibbs free energy model. The coefficients of the NRTL model and the binary interaction parameters of six mixing rules with two EOSs (PR and SRK EOSs) have been determined for 100 data sets of 23 binary systems over a wide range of temperatures and pressures covering more than 970 experimental data points which are reported in the literature. The results show that the PR EOS with the new mixing rule model is more accurate than the PR and SRK EOSs with the other mixing rules for solid solubility calculations in supercritical carbon dioxide. The regressed interaction parameters of the binary system, without any further modification, were then extended to four ternary mixtures, giving satisfactory results of the solid solubilities in supercritical CO 2.

Silver-catalyzed activation of internal propargylic alcohols in supercritical carbon dioxide: efficient and eco-friendly synthesis of 4-alkylidene-1,3-oxazolidin-2-ones

The silver-catalyzed cycloaddition reactions of carbon dioxide with internal propargylic alcohols and primary amines under supercritical conditions give 4-alkylene-1,3-oxazolidin-2-ones in good to excellent yields. The optimized conditions are to use an alcohol (2 mmol), an amine (2 mmol), silver acetate (0.1 mmol), and carbon dioxide (8 MPa) at 120 °C.

Phase equilibria of alcohols in supercritical fluids: Part I. The effect of the position of the hydroxyl group for linear C 8 alcohols in supercritical carbon dioxide

The ability to model and predict the behaviour of high-pressure alcohol and carbon dioxide mixtures is important for industrial purposes. The phase equilibria behaviour of four 8-carbon alcohols in supercritical carbon dioxide are measured to determine the effect of the hydroxyl group position on alcohol solubility. Experimental bubble- and dew point data are generated on a high pressure phase equilibrium cell for the systems 1-octanol, 2-octanol, 3-octanol and 4-octanol in supercritical carbon dioxide between 35 °C and 75 °C. 1-Octanol is shown to be the least soluble and, at 35 °C, exhibits a phase transition pressure 85 bar higher than that of 2-octanol. 1-Octanol also exhibits a temperature inversion near the critical temperature of carbon dioxide in the mixture critical region. 2-Octanol possesses marginally higher phase transition pressures than 3-octanol which, in turn, possesses marginally higher phase transition pressures than 4-octanol. This difference in phase equilibria is believed to result from a difference in polarity. Shifting the hydroxyl group from the first to the second carbon atom causes a large decrease in polarity and increase in solubility. Further movements toward the molecule centre result in progressively smaller polarity reductions and solubility increases, producing phase boundaries that coincide or differ minimally.

MCM-48 Supported Tungstophosphoric Acid: An Efficient Catalyst for the Esterification of Long-Chain Fatty Acids and Alcohols in Supercritical Carbon Dioxide

Tungstophosphoric acid (HPW) and MCM-48-supported HPW catalysts are potential catalysts for the esterification of long-chain fatty acids and alcohols in supercritical CO2 medium even at low temperature (100 °C) and a short reaction period (6 h). The high performances of HPW in sc-CO2 medium are due to the effective mass transfer of reactants and products for the catalysis under the conditions. The yields of esters were enhanced with the increase in the chain length of acids and alcohols in the esterification in sc-CO2 medium. The MCM-48-supported HPW catalysts were active even after several recycle experiments.

Gold catalysed selective oxidation of alcohols in supercritical carbon dioxide

The oxidation of benzyl alcohol to benzaldehyde over different supported gold catalysts in supercritical carbon dioxide has been investigated in a high-pressure batch reactor. Only molecular oxygen was used as oxidant and no base was needed. Different supports and preparation methods for the catalysts were tested and parameters like reaction temperature, pressure and molar ratios of the components were varied to study the catalytic behaviour. Gold colloids deposited on a titania support (1%Au/TiO2) yielded a conversion of 16.0% after 3 h and a high selectivity to benzaldehyde of 99% under single-phase conditions. The reaction rate was significantly higher than in a corresponding “solvent-free” reaction without CO2. Even higher rates were found when a CO2-expanded phase was present. Monitoring of the oxidation in a high-pressure view cell via infrared transmission spectroscopy unravelled a slowdown of the reaction rate above 15% conversion. In addition, 1-octanol and geraniol were oxidised as well under similar conditions, yielding conversions of 4% and 10%, respectively, with selectivities towards octanal and geranial of 90% and 30%. Thus, the combined application of gold-based catalysts and supercritical CO2 offers an interesting alternative to the known methods of alcohol oxidation.

Stereoselective Formation of α‐Alkylidene Cyclic Carbonates via Carboxylative Cyclization of Propargyl Alcohols in Supercritical Carbon Dioxide.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Stereoselective Formation of α-Alkylidene Cyclic Carbonates via Carboxylative Cyclization of Propargyl Alcohols in Supercritical Carbon Dioxide

Carboxylative cyclization of propargyl alcohols in supercritical carbon dioxide (scCO2) containing P(n-C4H9)3 as a catalyst proceeded smoothly to give alpha-alkylidene-1,3-dioxolan-2-ones. Internal propargyl alcohols afforded Z-alkyl-idene cyclic carbonates exclusively. CO2 incorporation was markedly promoted under supercritical conditions, possibly due to the facile formation of a putative P(n-C4H9)3-CO2 adduct as a key intermediate.

The co-solubility of 2-ethylhexanoic acid and some liquid alcohols in supercritical carbon dioxide

The co-solubility in supercritical carbon dioxide of 1-butanol, 1-pentanol, 2-ethyl-1-hexanol, or 1-decanol in the presence of 2-ethylhexanoic acid in the pressure range of 100–180 bar and at 313 or 323 K was measured. The solubility of these alcohols in the presence of 2-ethylhexanoic acid is lower than in the systems alcohol + CO 2 and remains nearly constant in the pressure range of 120–180 bar, with the exception of 1-decanol. The lower selectivities in the ternary systems are explained by strong intermolecular hydrogen bonding between alcohol molecules and 2-ethylhexanoic acid molecules. The FT-IR spectra of mixtures of alcohols and 2-ethylhexanoic acid at a 1:1 mole ratio in the liquid CCl 4 confirmed this conclusion.

Heptadecafluorooctanesulfonic acid catalyzed ring opening reactions of methylenecyclopropanes with aromatic amines, sulfonamides and alcohols in supercritical carbon dioxide

The ring opening reactions of methylenecyclopropanes (MCPs) with ArNH2, RSO2NH2 and alcohols can be carried out in scCO2 in the presence of heptadecafluorooctanesulfonic acid which offer a way to synthesize homoallylic amines, sulfonamides and ethers in environmentally benign conditions.

Correlation of Solubilities and Entrainer Effects for Fatty Acids and Higher Alcohols in Supercritical Carbon Dioxide Using SRK Equation of State with Association Model.

Solubilities of fatty acids (myristic acid, palmitic acid and stearic acid) and higher alcohols (cetyl alcohol, stearyl alcohol and arachidyl alcohol) in supercritical CO2, and the entrainer effect (ethanol or octane) on their solubilities, are correlated by the Soave-Redlich-Kwong equation of state with an association model. It is assumed that the system consists of supercritical CO2, solute monomer, solute dimer, hydrogen bonding species between solute monomer and entrainer, and entrainer. The mole fractions of these species are determined by the equilibrium constants for dimerization of palmitic acid, and those for hydrogen bonding species between palmitic acid and ethanol obtained from FTIR spectroscopic study. The calculated results agreed with the experimental data.

Partial oxidation of alcohols in supercritical carbon dioxide

Oxidation of water-insoluble alcohols in supercritical CO2 over a Pd–Pt–Bi/C catalyst in a continuous fixed bed reactor affords high reaction rates and yields up to 98% of the corresponding ketones, aromatic and α,β-unsaturated aliphatic aldehydes, without the risk of using a flammable organic solvent.

Influence of cosolvent on solubilities of fatty acids and higher alcohols in supercritical carbon dioxide

Influences of cosolvents on the solubilities of fatty acids (palmitic acid (C 15H 31COOH) and stearic acid (C 17H 35COOH)) and higher alcohols (cetyl alcohol (C 16H 33OH) and stearyl alcohol (C 18H 37OH)) in supercritical carbon dioxide were measured by using a flow-type apparatus. Experiments were carried out at 308.2 K under 9.9, 14.8 and 19.7 MPa. Ethanol and octane were used as cosolvents. The concentration of cosolvent was up to 10 mol %. The experimental results were correlated by the regular solution model coupled with the Flory-Huggins theory using the local composition of cosolvent around the solute molecule.

Monte Carlo simulation of n-paraffins and higher alcohols in supercritical carbon dioxide

Monte Carlo simulation has been applied to calculate the static properties of n-paraffins; octacosane (C 28H 58) and triacontane (C 30H 62) and higher alcohols; cetyl alcohol (C 16H 33OH), stearyl alcohol (C 18H 37OH) and arachidyl alcohol (C 20H 41OH) in supercritical carbon dioxide at 308.2 K. Carbon dioxide was treated as single site molecule for simplification, while chain molecules (n-paraffins and higher alcohols) were approximated as many sites molecules. The residual chemical potential was calculated by the isothermal-isobaric Kirkwood method. It was shown that the solubilities (solid-gas equilibria) of n-paraffins and higher alcohols in supercritical carbon dioxide can be calculated quantitatively by introducing only one intermolecular parameter between unlike sites. The calculated results of mean-square end-to-end separations of n-paraffins increases with the pressure both in supercritical carbon dioxide and in supercritical ethane. The mean-square end-to-end separations of n-paraffins in supercritical carbon dioxide are shorter than those in supercritical ethane. Furthermore, the first peaks of the radial distribution functions of carbon dioxide for n-paraffins are lower than those of ethane for n-paraffins. These facts mean that supercritical carbon dioxide acts to n-paraffins as a poor solvent compared with supercritical ethane. The radial distribution functions of carbon dioxide for higher alcohols imply that carbon dioxide tends to cluster around hydroxyl group.

Correlation of solubilities of fatty acids and higher alcohols in supercritical carbon dioxide with cosolvent using virial equation of state.

In this study, we attempted to correlate the solubilities and the solubility enhancement using the Leiden type virial equation of state

Solubilities of stearic acid, stearyl alcohol, and arachidyl alcohol in supercritical carbon dioxide at 35.degree.C

The solubilities of stearic acid (octadecanoic acid), stearyl alcohol (1-octadecanol), and arachidyl alcohol (1-eicosanol) in supercritical carbon dioxide were measured by using a flow-type apparatus at 35 C up to 23.7 MPa. The solubilities of those substances and other fatty acids and higher alcohols in supercritical carbon dioxide at 35 C were correlated by a solution model based on the regular solution model coupled with the Flory-Huggins theory.