Nowadays, green extraction processes are focused on the development of new strategies to achieve sustainable separation processes, promoting the use of alternative solvents from renewable sources. ...Green solvents have risen as an option that can replace petroleum based solvents, however, they should retain the same extraction properties and technological features. The choice of the solvent is a crucial step in the solvent-substitution process, so Hansen solubility parameters (HSP) have been successfully used as a real decision-making tool. For the first time, this work aims to give an overview of HSP as solvent selection tool for extraction of bioactive compounds from natural products. It includes a brief description about the emerging green solvents extraction, the HSP theory and an updated discussion of the most recent publications (from 2009 till January 2019). Finally, some concluding remarks about the importance of using this solvent selection approach in the near future are included.
•Hansen solubility parameters is used as solvent selection tool for green extraction.•In the last 10 years, there has been a notably increase on HSP research publications.•Emerging extraction technologies have been employed Hansen approach with success.•Solubility of terpenes, phenolic compounds and fatty acids have been predicted by HSP.•COSMO-RS is another powerful approach employed to understand solubility mechanism.
Rosmarinus officinalis L. is one of the most widely exploited medicinal plants for its bioactive compounds, including rosmarinic acid (RA), carnosic acid (CA) and carnosol (CAR). This study aims to ...selectively extract these compounds, using supercritical fluids extraction with carbon dioxide and ethanol as co-solvents, based on the Hansen solubility parameters approach. This approach predicted that CA and CAR are highly soluble in the supercritical fluid. However, a weak interaction was predicted between RA and this fluid. The experimental findings indicated the highest amounts of RA and CA were observed at 150 bar and 80°C, resulting in yields of 3.43 mg/g dry weight (DW), and 18.9 mg/g DW, respectively. Favourable extraction conditions for CAR were recorded at 250 bar and 40°C, with a content of 19.1 mg/g DW. Evaluation of antioxidant activity using DPPH tests revealed that extracts obtained at 250 bar at 40 and 80°C rich in CAR have a stronger antioxidant power.
Display omitted
•A study was conducted on SCF solubility dynamics and rosemary compound extraction.•Solubility parameters were used to define optimal conditions for selective extraction.•Rosmarinic acid and carnosic acid were best extracted at 150 bar and 80°C.•An enhanced antioxidant activity was observed in the extracts rich in carnosol.
Display omitted
•The traditional homomorph concept contains ambiguities and may underlie experimental issues.•« COSMOmorph » provides a robust prediction of Hansen’s dispersive solubility parameters ...δD.•Calculated δD are in reasonable agreement with published values for 90 organic solvents.
A simple approach to predict dispersive Hansen solubility parameter δD is proposed, taking advantage of the separation of energies in the COnductor-like Screening MOdel for Realistic Solvation (COSMO-RS). The “COSMOmorph”, that is, the COSMO file(s) with all surface charge densities and dielectric energy equal to zero, allows an unambiguous splitting of energies and choice of structures and removes the requirement for the experimental existence of a homomorph. Reasonable agreement between δD of COSMOmorph and published δD for 89 solvents is obtained, with a standard deviation of 1.0 MPa1/2. Note that perfect agreement is not expected due to the shortcomings of the historical method.
After thousands of articles on solubility science (broadly including ‘similarity’ and ‘compatibility’) over the past decades, the formulator has been provided with surprisingly few tools that can ...help solve problems in the necessarily messy world of complex formulations. This failure of much of the academic enterprise has led to a culture of trial-and-error in formulation. Although a very few tools are of enduring value in solubility-related work, only one, currently, has a broad applicability across the range of solubility and compatibility problems faced by formulators. This tool is the Hansen Solubility Parameter (HSP) approach, which despite its many acknowledged faults and limitations is powerful and general enough to be able to guide users through formulation space with the help of on-line apps and data sets. The challenge for academics is not to fiddle with current tools but to think big and find new tools to exceed the power and generality of HSP.
Display omitted
Ruta graveolens L. is considered an important source of alkaloids and furanocoumarins, with attributed biological activity against phytopathogenic microorganisms. Pressurized liquid extraction (PLE) ...and supercritical fluid extraction (SFE) using bio-based solvents are green alternative extraction techniques to obtain specific type of compounds. From aerial parts, terpenes were favorably extracted by PLE, while by SFE using batch extraction, different fractions were obtained depending on the extraction pressure: at 200 bar, fatty acids enrichment was achieved from dry sample, while at 350 bar mainly alkaloids and furanocoumarins were obtained from moistened sample. Coumarins were extracted mainly from roots by the two extraction techniques tested. However, this family is always extracted together with alkaloids and furanocoumarins. Therefore, in this work a green methodology has been developed to obtain rue extracts enriched in different families of biologically active substances that could have antifungal or nematicidal activity for pathogen control in agricultural activities.
Display omitted
•Green PLE and SFE procedures to obtain enriched extracts in bioactives from rue.•PLE extraction solvents selected through Hansen solubility parameters.•PLE extraction conditions selected through response surface plots.•SFE selectivity obtained by batch extraction of dry or moistened samples.•103 compounds tentatively identified of which 63 detected for the first time in rue.
•Hansen solubility parameters are estimated using regularized regression.•Regularized regression is applied with adaptable, flexible group contribution.•Solubility parameters are estimated for novel ...biomass-derived compounds.•Low computational cost parameter modeling requires no proprietary software.•This approach shows promise for extension to modeling other properties.
Biomass conversion technologies yield unique products for which laboratory characterization of structure and properties is an ongoing challenge. In this study, Hansen solubility parameters are estimated using regularized regression as a platform for adaptable group contribution. A training set of small molecules and a set of biomass conversion molecules are parameterized using simple contributing groups. Regularized regression is then applied as a tool to reduce model complexity. This allows for flexible development of contributing groups, which are then down-selected to those which are most important, while avoiding overfitting. The model is built upon experimental data and uses only python and its science/data analysis libraries. The model also shows good agreement with other published work designed for “pencil and paper” estimation of solubility parameters. The combination of regularized regression with adaptable group contribution has potential for applications in prediction of other molecular properties for which group contribution methods are commonly employed.
Despite great advances in carbon synthesis through solution chemistry, a long-standing question is how to choose solvents effectively. Herein, we establish a systematical strategy to answer this ...question, guided by both the difference of total Hansen solubility parameter and the relative energy difference between the solvent and the precursor. This approach can quickly and accurately screen out the “excellent” solvent or solvent mixture from a lot of possible candidates including single, binary and multicomponent systems to synthesize carbon materials with optimal nanostructure and high surface area. We further find it is convenient to get a series of “excellent” solvents by mixing different grades of solvents (“poor”, “fair”, and “good”). This finding gives more opportunities for solvent choice to fabricate well-designed carbons, and also provides an economic and eco-friendly synthetic route by selecting cheap, low- or non-toxic solvents. The robust strategy, which has been applied to different carbon precursors, has already succeeded as a proof of concept. As-synthesized carbons feature sphere-like superstructure and high surface area, delivering fast electrochemical kinetics, ultrahigh energy density and excellent high-rate lifespan in energy storage applications.
We establish a systematical strategy to quickly and accurately screen out the excellent solvents from a series of candidates including single, binary and multicomponent system to synthesize optimized carbons for efficient energy storage. Display omitted
•New Swell-Cavity Ratio parameter was used to characterize transport channel changes.•A model was built about the Hansen solubility parameter and Swell-Cavity Ratio.•Membrane mass transfer mechanism ...greatly affects the trend of the Swell-Cavity Ratio.•The model can accurately calculate the membranes pore changes in organic solvents.•The model is instructive for the application agility of membrane in organic solvents.
The relationship between swelling, the difference (Δδ) in theoretical Hansen solubility parameters (HSP) between the two substances, and the change of membrane mass-transfer channel has been controversial. In this work, a completely new parameter, Swell-Cavity Ratio (SCR), defined as the ratio of membrane molecular weight cut off (MWCO), was introduced to characterize the changes in mass transfer channels before and after membrane swelling. Models of the relationship between Δδ and SCR were successfully constructed for nanoporous glassy (SCR = 0.19 × Δδ0.40) and rubbery (SCR = 17.7 × Δδ-0.93) membranes, using the swelling as a bridge. Based on this contradiction in models, we speculate that SCR variation is strongly related to the separation mechanism of the membranes. The theoretical model accurately calculates the influence of the solvent on the membrane mass transfer channel, allowing for the selection of the best membrane material and pretreatment process to maximize treatment efficiency.
Simple inorganic salts are used to tune N‐containing conjugated microporous polymers (CMPs) synthesized by Buchwald–Hartwig (BH) cross‐coupling reactions. Poly(triphenylamine), PTPA, initially shows ...a broad distribution of micropores, mesopores, and macropores. However, the addition of inorganic salts affects all porous network properties significantly: the pore size distribution is narrowed to the microporous range only, mimicking COFs and MOFs; the BET surface area is radically improved from 58 m2 g−1 to 1152 m2 g−1; and variations of the anion and cation sizes are used to fine‐tune the surface area of PTPA, with the surface area showing a gradual decrease with an increase in the ionic radius of salts. The effect of the salt on the physical properties of the polymer is attributed to adjusting and optimizing the Hansen solubility parameters (HSPs) of solvents for the growing polymer, and named the Beijing–Xi'an Jiaotong (BXJ) method.
Porous, with a pinch of salt: The discovery of the BXJ approach, where salts are used to carefully tune N‐containing conjugated microporous materials, is reported. This approach enables the preparation of amorphous porous materials that start to challenge COFs and MOFs in properties and function.
Display omitted
Pharmaceutical co-crystals present an opportunity to improve the solubility of conventional active pharmaceutical ingredients (APIs). Despite advances in co-crystal screening, the ...rational design of even the chemically simplest co-crystals remains challenging. Hansen solubility parameters (HSPs) have previously been used as a tool to predict co-crystal formation using only the chemical structure. The aim of this study was to validate the use of HSPs as a tool to predict co-crystal formation, analyse its limitations and examine the previously set Δδ inclusion cut-off value. A total of 109 co-formers of carbamazepine, caffeine and theophylline were used as a training set. Sixteen different descriptors were examined. An additional 72 co-formers of piroxicam and nicotinamide were used to test the methods and new cut-off values. The established cut-off value (8.18 MPa0.5) despite being similar to the previously reported value (7 MPa0.5), offered no real advantage over the previously reported value. Our results suggest the use of the modified radius (Ra) method of calculating the solubility difference, which had higher sensitivity of 90% compared to 86% for the previously reported method and cut-off value to indicate co-crystal formation as well as a lower miss and false omission rates.
PDF
