Cinzia Chiappe

Acute toxicity of ionic liquids to the zebrafish (Danio rerio)

Acute toxicity and histological damage derived from exposure of Danio rerio (zebrafish) to several ionic liquids have been evaluated.

Validation of the copper(i)-catalyzed azide-alkyne coupling in ionic liquids. Synthesis of a triazole-linked C-disaccharide as a case study.

The first study of a copper(I)-catalyzed azide-alkyne click reaction in ionic liquids (ILs) is reported. The cycloaddition of a sugar azide with a sugar acetylene (CuI, i-Pr2EtN, 80 degrees C) was carried out in 10 ILs as well as in standard molecular solvents (toluene and DMF) to give the 1,4-disubstituted triazole-linked C-disaccharide. The highest yields (84 and 95%) were registered in Ammoeng 110 and [C(8)dabco][N(CN)(2)]. The latter solvent was recycled in four subsequent reactions without loss of the reaction efficiency. Reactions carried out in the absence of the Hünigs base afforded mixtures of 1,4- and 1,5-disubstituted triazole regioisomers.

A rationalization of the solvent effect on the Diels–Alder reaction in ionic liquids using multiparameter linear solvation energy relationships

The Diels-Alder reaction between cyclopentadiene and three dienophiles (acrolein, methyl acrylate and acrylonitrile) having different hydrogen bond acceptor abilities has been carried out in several ionic liquids and molecular solvents in order to obtain information about the factors affecting reactivity and selectivity. The solvent effects on these reactions are examined using multiparameter linear solvation energy relationships. The collected data provide evidence that the solvent effects are a function of both the solvent and the solute. For a solvent effect to be seen, the solute must have a complimentary character; selectivities and rates are determined by the solvent hydrogen bond donation ability (alpha) in the reactions of acrolein and methyl acrylate, but not of acrylonitrile.

Are ionic liquids a proper solution to current environmental challenges

It is well known that ionic liquids (ILs) possess extraordinary characteristics, making them greener solvents with unique properties, which allow processes that would otherwise be difficult or impossible with common solvents to be carried out. In this review, we describe and discuss, in the light of possible future large scale applications, some fundamental studies showing the efficacy of ILs in several “hot” fields, from dissolution and transformation of biopolymers to extraction and capture of important inorganic components (metals) or pollutants (CO2).

Influence of Structural Variations in Cationic and Anionic Moieties on the Polarity of Ionic Liquids

The polarity of a series of ionic liquids (ILs) arising from the quaternarization of N-methylmorpholine, N-methylpyrrolidine, N-methylpiperidine, N-methylazepane, 4-hydroxy-1-methylpiperidine, 1,2-dimethylimidazole, and 1-methylimidazole with simple alkyl chains and/or hydroxyl (mono- or dihydroxyl) functionalized alkyl chains and having bistriflimide, dicyanamide, or nitrate as counteranions has been investigated using solvatochromic dyes and expressed in terms of E(T)(N) and Kamlet-Taft parameters (dipolarity/polarizability (π*), hydrogen bond donor acidity (α), and hydrogen bond basicity (β)). Significant variations of polarity were observed on changing the anion and cation combination. The resulting E(T)(N) and α values were strongly anion dependent; on going from bistriflimide to dicyanamide, a significant decrease in E(T)(N) and α values was observed. On the other hand, the alkyl chain length has only a moderate effect on these parameters; either an increase or decrease in E(T)(N) and α values was observed on increasing the alkyl chain length, depending on the cation core. In the case of cyclic onium salts, the size of the cation ring affected the α parameter; the ILs based on the seven-membered ring system N-methyl-N-butylazepanium (also named N-methyl-N-butylhexamethyleneiminium, [HME(1,4)](+)) have high polarity values, comparatively to the ILs based on analogous five- and six-membered cyclic cations (pyrrolidinium and piperidinium). The introduction of the OH groups on the cation alkyl chain increases the polarity; the effect is substantial for the first OH group and more moderate for the second. Also, the thermosolvatochromism (changes in solvatochromic properties with the change in temperature) was studied for four dihydroxyl functionalized ILs. Finally, the principal component analysis (PCA) carried out on 67 ILs has shown that there are only two statistically relevant parameters: PC1, a weighted sum of E(T)(N) and α, which is able to discern between the cation core structure, functionalization, and cation-anion association, and PC2, very close to β, which is related principally to the anion nature.

The Heck reaction in ionic liquids: progress and challenges.

As the interest for environmental increases and environmental laws become more stringent, the need to replace existing processes with new more sustainable technologies becomes a primary objective. The use of ionic liquids to replace organic solvents in metal catalyzed reactions has recently gained much attention and great progress has been accomplished in this area in the last years. This paper reviews the recent developments in the application of ionic liquids and related systems (supported ionic liquids, ionic polymers, and so on) in the Heck reaction. Merits and achievements of ionic liquids were analyzed and discussed considering the possibility of increasing the effectiveness of industrial processes.

The solvent effect on the Diels–Alder reaction in ionic liquids: multiparameter linear solvation energy relationships and theoretical analysis

This review illustrates how ionic liquid properties can affect Diels–Alder reactions. The mechanisms by which ionic solvents enhance the rate and selectivity of the reaction are discussed on the basis of correlation studies using empirical parameters and theoretical calculations.

Ecotoxicity of pristine graphene to marine organisms

The ecotoxicity of pristine graphene nanoparticles (GNC1, PGMF) in model marine organisms was investigated. PGMF resulted more toxic than GNC1 to the bioluminescent bacterium Vibrio fischeri and the unicellular alga Dunaliella tertiolecta on the basis of EC50 values (end-points: inhibition of bioluminescence and growth, respectively). No acute toxicity was demonstrated with respect to the crustacean Artemia salina although light microscope images showed the presence of PGMF and GNC1 aggregates into the gut; a 48-h exposure experiment revealed an altered pattern of oxidative stress biomarkers, resulting in a significant increase of catalase activities in both PGMF and GNC1 1mg/L treated A. salina and a significant increase of glutathione peroxidase activities in PGMF (0.1 and 1mg/L) treated A. salina. Increased levels of lipid peroxidation of membranes was also observed in PGMF 1mg/L exposed A. salina.

Preparative synthesis of chiral alcohols by enantioselective reduction with Daucus carota root as biocatalyst

Abstract The enzymatic reduction of (±)-2-methylcyclohexanone with fresh carrot root as biocatalyst occurred in a complete diastereoisomeric way giving a 1:1 mixture of enantiomerically pure (1S,2R)- and (1S,2S)-2-methylcyclohexanol. The analogous reaction carried out on the racemic 2-hydroxycyclohexanone afforded a 1:2 mixture of (1S,2R)- and (1S,2S)-1,2-cyclohexanediol with an enantiomeric excess >95%. The low cost and the easy availability of the biocatalyst besides the very simple reaction conditions suggest the possible use of the present method for large scale preparations of important chiral alcohols.

Ionic liquids: Solvation ability and polarity

The role of ionic liquids (ILs) as solvents in chemistry is limited by the poor understanding of the solvation phenomenon in these media. The usual classification criteria used for molecular solvents through various experimental measurements fail to insert ILs into a univocal classification for ILs. Here, we first discuss the unsuitability of the usual interpretative scheme for molecular liquids and elucidate schematically the mechanism of solvation in ILs, pointing out the peculiarities that differentiate them with respect to molecular liquids. Second, we focus on reactivity and reaction kinetics in ILs, underlining the many problems that the complexity of these media reflects on the interpretation of kinetic data and some possible approaches to understand qualitatively the (often not trivial) kinetic problems for reactions performed in ILs.