"Greener" Synthesis of Zoledronic Acid from Imidazol-1-yl-acetic Acid and P-Reagents Using Diethyl Carbonate as the Solvent Component

The synthesis of a third generation dronic acid, zoledronic acid by the reaction of imidazol-1-yl-acetic acid with phosphorus trichloride/phosphorous acid in diethyl carbonate (DEC) as a "green" solvent, and in DEC – methanesulfonic acid (MSA) solvent mixtures is described. The earlier not "green" and expensive MSA and sulfolane solvents may be re-placed by DEC

Assessment of the Organocatalytic Activity of Chiral L-Proline-Based Deep Eutectic Solvents Based on their Structural Features

<div><div><div><p>In this paper L-Proline-based Chiral Deep Eutectic Solvents (CDESs) were prepared and used as green and organocatalytic reaction media in a probe asymmetric Michael addition; in this reaction the L-Proline acts as solvent component as well as chiral organocatalyst. The results were analysed with NMR studies taking in account the availability of the L-Proline considering the strength of the association of it with the counterpart of the liquids. With DFT studies, the geometry and energy of the adducts are showed and a qualitative rationale to the reaction stereoisomers distribution is given.</p></div></div></div>

Assessment of the Organocatalytic Activity of Chiral L-Proline-Based Deep Eutectic Solvents Based on their Structural Features

<div><div><div><p>In this paper L-Proline-based Chiral Deep Eutectic Solvents (CDESs) were prepared and used as green and organocatalytic reaction media in a probe asymmetric Michael addition; in this reaction the L-Proline acts as solvent component as well as chiral organocatalyst. The results were analysed with NMR studies taking in account the availability of the L-Proline considering the strength of the association of it with the counterpart of the liquids. With DFT studies, the geometry and energy of the adducts are showed and a qualitative rationale to the reaction stereoisomers distribution is given.</p></div></div></div>

Counterintuitive solvation effect of ionic-liquid/DMSO solvents on acidic C–H dissociation and insight into respective solvation

The dependence of PhCH(CN)2 pKa on the molar fraction of ionic liquids in ionic–molecular binary mixtures showed a nonlinear three-fragment plot, which was rationalized for the first time by the respective roles of each solvent component for solvation.

Dissolution and recovery of cellulose from pine wood bits in ionic liquids and a co-solvent component mixed system

The dissolution and recovery of cellulose from pine wood bits with two types of ionic liquids and co-solvents were explored. The results revealed that 1-ethyl-3-methylimidazolium diethylphosphonate ionic liquid/dimethylsulfoxide (mass ratio 1:0.5) could dissolve pine cellulose within 8 min at 105°C. Moreover, the degree of polymerization of the regenerated cellulose reached 244. The dissolved cellulose could be regenerated from the component solution when water was added. Then, the regenerated cellulose was characterized by X-ray powder diffraction, Fourier-transform infrared spectroscopy, and thermal gravimetric analysis measurements. The results revealed that there was no derivatization of the reaction in the process of dissolution and that dissolving the pine cellulose was a direct process. The crystalline structure of the cellulose was converted from cellulose I to cellulose II after regeneration. The regenerated cellulose was also found to have good thermal stability.

Synthesis of spiro[indoline-3,3′-pyrrolizines] by 1,3-dipolar reactions between isatins, L-proline and electron-deficient alkenes

Two spiro[indoline-3,3′-pyrrolizine] derivatives have been synthesized in good yield with high regio- and stereospecificity using one-pot reactions between readily available starting materials, namely L-proline, substituted 1H-indole-2,3-diones and electron-deficient alkenes. The products have been fully characterized by elemental analysis, IR and NMR spectroscopy, mass spectrometry and crystal structure analysis. In (1′RS,2′RS,3SR,7a′SR)-2′-benzoyl-1-hexyl-2-oxo-1′,2′,5′,6′,7′,7a′-hexahydrospiro[indoline-3,3′-pyrrolizine]-1′-carboxylic acid, C28H32N2O4, (I), the unsubstituted pyrrole ring and the reduced spiro-fused pyrrole ring adopt half-chair and envelope conformations, respectively, while in (1′RS,2′RS,3SR,7a′SR)-1′,2′-bis(4-chlorobenzoyl)-5,7-dichloro-2-oxo-1′,2′,5′,6′,7′,7a′-hexahydrospiro[indoline-3,3′-pyrrolizine], which crystallizes as a partial dichloromethane solvate, C28H20Cl4N2O3·0.981CH2Cl2, (II), where the solvent component is disordered over three sets of atomic sites, these two rings adopt envelope and half-chair conformations, respectively. Molecules of (I) are linked by an O—H...·O hydrogen bond to form cyclic R 6 6(48) hexamers of \overline{3} (S 6) symmetry, which are further linked by two C—H...O hydrogen bonds to form a three-dimensional framework structure. In compound (II), inversion-related pairs of N—H...O hydrogen bonds link the spiro[indoline-3,3′-pyrrolizine] molecules into simple R 2 2(8) dimers.

The solvent component of macromolecular crystals

The mother liquor from which a biomolecular crystal is grown will contain water, buffer molecules, native ligands and cofactors, crystallization precipitants and additives, various metal ions, and often small-molecule ligands or inhibitors. On average, about half the volume of a biomolecular crystal consists of this mother liquor, whose components form the disordered bulk solvent. Its scattering contributions can be exploited in initial phasing and must be included in crystal structure refinement as a bulk-solvent model. Concomitantly, distinct electron density originating from ordered solvent components must be correctly identified and represented as part of the atomic crystal structure model. Herein, are reviewed (i) probabilistic bulk-solvent content estimates, (ii) the use of bulk-solvent density modification in phase improvement, (iii) bulk-solvent models and refinement of bulk-solvent contributions and (iv) modelling and validation of ordered solvent constituents. A brief summary is provided of current tools for bulk-solvent analysis and refinement, as well as of modelling, refinement and analysis of ordered solvent components, including small-molecule ligands.