Béla Simándi

Supercritical Fluid Extraction of Volatile Compounds from Lavandin and Thyme

Supercritical fluid extraction (SFE) of lavandin flowers and thyme herb using carbon dioxide was carried out under different extraction conditions. A stepwise increase of the extraction pressure resulted in the fractionation of the extracts into liquid and pasty products. Investigations on other ways of fractionation of the extracts were conducted, such as a single extraction and release of carbon dioxide at two stages by using two separators in series to effect the separation of the dissolved components. The SFE products were compared with essential oils obtained by conventional steam distillation. In the case of lavandin flowers, SFE products were found to be markedly different from the corresponding steam distilled oil. A remarkable amount of α-terpineol was present, and the ratio of linalol to linalyl acetate was extremely high in the steam-distilled essential oil in comparison with the supercritical fluid extract, which resulted from the hydrolysis of components during steam distillation. SFE of thyme gave a product which contained 10–15% thymol and 30–35% carvacrol, while steam distillation produced an oil containing 48–50% thymol and only 8–10% carvacrol. When the SFE products were collected as separate samples successively in time, marked changes were observed in the composition of the samples as the extraction progressed.

Supercritical carbon dioxide extraction and fractionation of oregano oleoresin

The leaves of Origanum vulgare L. (Lamiaceae) harvested in different countries, three samples from Hungary and one from Turkey, were extracted with carbon dioxide in a high pressure apparatus with a 5 1 extractor vessel volume. Total extractions with stagewise precipitation of the extracts were carried out in order to obtain essential oil-rich liquid and pasty products. A fractionated extraction with a stepwise increase of the extraction pressure was also performed to obtain portions of extracts of different quality. The extraction with carbon dioxide was compared to conventional steam distillation and to Soxhlet extraction with hexane, whith the goal of recovering essential oils and oleoresin products, respectively

Molecular chiral recognition in supercritical solvents

Abstract The intensity of molecular chiral interactions resulting in differences between physical and chemical properties of diastereomeric molecules is solvent dependent. This difference makes it possible to separate the enantiomers of a given substance by using chiral agents. A solvent of supercritical state was involved to study its influence on molecular chiral recognition. It was observed that the differences between the diastereomers in supercritical CO 2 are so big compared to traditional solvents that a novel, more efficient method for optical resolution can be developed, employing a variety of resolution agents in a much wider range than it was previously assumed.

Kinetic resolution of 1-(benzofuran-2-yl)ethanols by lipase-catalyzed enantiomer selective reactions

Abstract Kinetic resolution of racemic 1-(benzofuran-2-yl)ethanols rac - 1a – d was performed by lipase-catalyzed enantiomer selective acylation ( E ≫100) yielding (1 R )-1-acetoxy-1-(benzofuran-2-yl)ethanes ( R )- 2a – d and (1 S )-1-(benzofuran-2-yl)ethanols ( S )- 1a – d in highly enantiopure form. The degree of enantiomer selectivity for enzymatic alcoholysis/hydrolysis processes starting from racemic 1-acetoxy-1-(benzofuran-2-yl)ethane rac - 2 was also tested under various conditions including supercritical CO 2 medium. Racemization-free lipase-catalyzed ethanolysis of the (1 R )-1-acetoxy-1-(benzofuran-2-yl)ethanes ( R )- 2a – d yielded almost quantitatively the enantiopure (1 R )-1-(benzofuran-2-yl)ethanols ( R )- 1a – d .

Supercritical fluid extraction: A novel method for the resolution of tetramisole

Abstract A new resolution method, based on the selective distribution of enantiomers between a chiral solid and an achiral supercritical fluid phase, is reported. The chiral solid phase is formed from the optically active dicarboxylic acid derivative, (2 R ,3 R )- O , O ′-dibenzoyltartaric acid, and the racemic base (tetramisole). A new method is also described for the enrichment of enantiomeric mixtures which have an enantiomeric ratio other than 1:1. This is based on the partial salt formation of the enantiomeric mixture with an achiral substance, which is then followed by supercritical fluid extraction of the free enantiomer. The extract has an enantiomeric composition which is different from the starting mixture. The method is applied to an enantiomeric mixture of tetramisole with hydrochloric acid.

Pilot-scale extraction and fractional separation of onion oleoresin using supercritical carbon dioxide

Abstract Supercritical carbon dioxide extraction of onion flavour was studied using a high pressure apparatus with a 5 l extractor vessel volume. Designed experiments were carried out to map quantitative effects of extraction pressure and temperature on the extraction yield and sulphur recovery. Stagewise precipitations of the extracts were carried out using two separators in series in order to obtain essential oil rich products with a high-sulphur content. The extraction with carbon dioxide was compared to conventional steam distillation and Soxhlet extraction with hexane and ethyl alcohol.

Recovery of a bioactive sesquiterpene lactone fromTanacetum parthenium by extraction with supercritical carbon dioxide

SummaryThe isolation of parthenolide-rich products from feverfew (Tanacetum parthenium (L.) Sch.) with supercritical carbon dioxide extraction has been investigated. A 32 full-factorial design was used to map the effects of pressure and temperature on the extraction yields and on the yield of parthenolide. The composition of the essential oil of feverfew obtained by hydrodistillation was compared with that of the SFE extract containing the volatile compounds.

Study on the pilot-scale extraction of onion oleoresin using supercritical CO2

Supercritical carbon dioxide (SC-CO2) was used to produce oleoresin from dried onion by pilot-scale extraction. The results showed that the extraction pressure and temperature affected the yield and sulphur concentration of onion oleoresin. Increase of the temperature from 45 to 65°C at 300 bar resulted in an increase of the yield and the sulphur concentration of oleoresin. At the same temperature (45°C) the yield was also higher at 300 bar than 100 bar while sulphur concentration of oleoresin got smaller at 300 bar than at 100 bar. The volatile composition of oleoresin displayed practically no differences as a function of extraction parameters. Comparison of different extraction methods showed that the yield after SC-CO2 extraction was 22 times higher than that after steam distillation, but it was 14 or 39 times less than that after alcohol extraction, shaking at 25°C or in Soxhlet apparatus, respectively. The concentration of sulphur was the highest in steam distilled onion oil while it was the lowest in the extract of hexane and alcohol (at 25°C). The results of sensory evaluation showed that oleoresin extracted by SC-CO2 was the first in ranking (at level of significance 0·05), before steam distilled oil and alcoholic extract. There was no significant difference between steam distilled oil and alcoholic extract in ranking, but the alcoholic extract was the least desirable, since the intensity of its off odour attribute was the highest.

A Comparison Between the Oil and Supercritical Carbon Dioxide Extract of Hungarian Wild Thyme (Thymus serpyllum L.)

ABSTRACT Two samples of wild thyme (Thymus serpyllum L.), which were collected from different locations in Hungary, were subjected to CO2 extraction and oil isolation by hydrodistillation. Using GC and GC/MS as the method of analysis their compositions were compared. Analysis revealed that the oils and extracts contained the same components although they differed quantitatively. The concentration of p-cymene, borneol, nerol and carvacrol was higher in the distilled oil than in the volatile concentrate obtained by SFE.

Influence of benzylamine on the resolution of ibuprofen with (+)-(R)-phenylethylamine via supercritical fluid extraction

The resolution of racemic ibuprofen was studied by partial diastereomer salt formation. The resolution was performed via two methods: resolution with (+)-(R)-phenylethylamine as chiral agent and resolution with a mixture of (+)-(R)-phenylethylamine and benzylamine. The diastereomers and unreacted enantiomers were separated by supercritical fluid extraction with carbon dioxide at 15 MPa and 33 degrees C. The influence of the achiral benzylamine on the resolution efficiency was studied by varying the concentrations of the structurally related amines in their mixtures, keeping the sum molar ratio of the amines to racemic ibuprofen constant at 0.55 +/- 0.02. The presence of benzylamine positively influenced the resolution efficiency at certain concentrations. The crystal structure of the salts of (+)-(R)-phenylethylamine with (-)-(R)-ibuprofen and (+)-(S)-ibuprofen, respectively, as well as the cocrystal of the benzylamine-ibuprofen salt with neutral ibuprofen molecules are presented. These structures were determined by single crystal X-ray diffraction, proving the significantly different stoichiometry of the related amines with the chiral acid, in accordance with mass balance calculations.