Andreia A. Rosatella

5-Hydroxymethylfurfural (HMF) as a building block platform: Biological properties, synthesis and synthetic applications

The biorefinery is an important approach for the current needs of energy and chemical building blocks for a diverse range of applications, that gradually may replace current dependence on fossil-fuel resources. Among other primary renewable building blocks, 5-hydroxymethylfurfural (HMF) is considered an important intermediate due to its rich chemistry and potential availability from carbohydrates such as fructose, glucose, sucrose, cellulose and inulin. In recent years, considerable efforts have been made on the transformation of carbohydrates into HMF. In this critical review we provide an overview of the effects of HMF on microorganisms and humans, HMF production and functional group transformations of HMF to relevant target molecules by taking advantage of the primary hydroxyl, aldehyde and furan functionalities.

Toxicity assessment of various ionic liquid families towards Vibrio fischeri marine bacteria

The increasing interest on the application of ionic liquids (ILs) to a wide range of processes and products has been hampered by a lack of toxicological data, mainly in what concerns novel cations, such as guanidinium, phosphonium, and functionalized and non-functionalized imidazolium-based ILs. The present study reports the toxicity of five guanidinium-, six phosphonium, and six imidazolium-based ILs, towards the luminescent marine bacteria Vibrio fischeri. These new results clearly show that guanidinium-, unlike the imidazolium- and phosphonium-based ILs, do not follow the trend of increasing toxicity with the increase in the alkyl chain length. Moreover, the introduction of oxygenated groups on the alkyl chains, such as ether and ester, leads to a decrease of the toxicity of guanidinium and also imidazolium compounds. In what respects the effect of the different cations, it is possible to recognize that the phosphonium-based ILs seem to be more toxic when compared to the analog imidazolium-based ILs (with the same anion and alkyl chains).

Toxicological evaluation on human colon carcinoma cell line (CaCo-2) of ionic liquids based on imidazolium, guanidinium, ammonium, phosphonium, pyridinium and pyrrolidinium cations

Toxicological evaluation of a new group of ionic liquids was performed on human colon cancerous cells—CaCo-2. They belong to different classes of cations: imidazolium (IM), dimethyl-guanidinium (dmg) and tetramethyl-guanidinium (tmg), methyl-pyrrolidinium (MPyr), 2-methyl-1-ethyl-pyridinium (2-MEPy), quaternary ammonium (benzyltriethyl-ammonium–BzTEA; phenyltrimethyl-ammonium–PhTMA; tri-n-octyl-methylammonium-Aliquat) and tri-n-hexyl-tetra-n-decylphosphonium (P6,6,6,14). The new results were compared with data obtained in previous reported studies performed in our lab, and we clearly saw that toxicity can vary significantly with the type of anion. Dicyanoamide-[DCA] and bis(trifluoromethanesulfonyl)amide-[NTf2] were seen to visibly change the impact of some cations. Some were considerably less harmful for CaCo-2 monolayer when the anion was [DCA] or [NTf2], while others induced an abnormal increase of cellular metabolism when [NTf2] was present and therefore, they were considered toxic. However, some cations induced similar responses in the presence of a broad number of anions as (1-butyl-3-methylimidazolium)-[C4MIM] (with the exception of [FeCl4]), (1-(2-hydroxyethyl)-3-methylimidazolium)-[C2OHMIM] and [C4MPyr] and did not cause toxicity. Consequently, they are considered promising cations for building human friendlier solvents. But, a reasonable number of other combinations involving different classes of cations were also seen to not significantly affect viability of the CaCo-2 monolayer.

Studies on dissolution of carbohydrates in ionic liquids and extraction from aqueous phase

An extended study on the solubility of the carbohydrates glucose, fructose, sucrose and lactose in twenty eight different ionic liquids (ILs) was performed. These ILs were based on the combination of tetraalkylammonium, tetraalkylphosphonium, 1-methyl-3-alkylimidazolium and dimethyl-tetraalkylguanidinium cations containing alkyl and ether pendant substituent groups, and anions of chloride, dicyanamide, saccharine, acesulfame, acetate or thiocyanate. It was possible to achieve solubilities, at 35 °C, of each carbohydrate up to 43.9, 49.0, 17.1 and 16.6% (g of carbohydrate per 100 g of IL), respectively. The possibility to extract carbohydrates from an aqueous phase by hydrophobic ILs was also demonstrated. Besides, some selectivity for a mixture of two carbohydrates was also observed.

Synthesis of 2,4,6-Tri-substituted-1,3,5-Triazines

Several specific synthetic protocols were developed for the preparation from cyanuric chloride of a range of symmetric and non-symmetric di- and tri-substituted 1,3,5-triazines containing alkyl, aromatic, hindered, chiral and achiral hydroxyalkyl, ester and imidazole groups via sequential nucleophilic substitution of the C-Cl bond by C-O, C-N and C-S bonds.

Toxicological evaluation of magnetic ionic liquids in human cell lines

Magnetic ionic liquids (MILs) are new solvents with an interesting broad of applications however their toxicity is still an open issue. In this paper we report the toxicity of [C(8)MIM] and [Choline-C(n)] based magnetic ionic liquids assessed in two human cell lines: normal skin fibroblasts (CRL-1502) and colorectal adenocarcinoma cells (CaCo-2), acquiring this last characteristics of human enterocytes after differentiation. The results showed that [CoCl(4)] and [MnCl(4)] are more prone to generate cytotoxicity.

Integrated desulfurization of diesel by combination of metal-free oxidation and product removal by molecularly imprinted polymers

The production of ultra-low-sulfur diesel is an important worldwide demand. In this work a novel integrated method for desulfurization of diesel is proposed based on the combination of Bronsted acid catalyzed oxidation and the selective removal of the oxidized products using a molecularly imprinted polymer (MIP) produced in supercritical carbon dioxide (scCO2). The biphasic oxidation reaction of dibenzothiophene sulfone (DBT), as model substrate, and H2O2 as oxidant, was optimized by testing different acid catalysts, and also different phase transfer catalysts (PTC), including two different ionic liquids (ILs) trihexyl(tetradecyl)phosphoniumchloride [P6,6,6,14]Cl and Aliquat®. The products of the efficient oxidation of DBT, dibenzothiophene sulfoxide (DBTSO) and dibenzothiophene sulfone (DBTSO2), were then selectively removed from real diesel using the MIP.

New low viscous cholinium-based magnetic ionic liquids

Magnetic ionic liquids (MILs) are a type of ionic liquids (ILs) that have paramagnetic metal based anions, and thus they can respond to an external magnetic field. Owing to the high propensity of these anions to crystallize, there are only few reported MILs that are liquid at room temperature. This study describes a new family of cholinium based ILs containing two and three ethanol side chains, that are liquid at room temperature, even in combination with paramagnetic anions. In addition, these new family of ILs are prone to the generation of low toxicities on human cell lines.

Ecotoxicological evaluation of magnetic ionic liquids

Although magnetic ionic liquids (MILs) are not yet industrially applied, their continued development and eventual commercial use may lead to their appearance into the aquatic ecosystem through accidental spills or effluents, consequently promoting aquatic contaminations. Furthermore, the deficient information and uncertainty surrounding the environmental impact of MILs could be a major barrier to their widespread industrial application and international registration. Thus, in the present work, a range of cholinium salt derivatives with magnetic properties was synthesized and their ecotoxicity was evaluated towards the luminescent bacteria Vibrio fischeri. The results suggest that all MILs structures tested are moderately toxic, or even toxic, to the bacteria. Furthermore, their toxicity is highly dependent on the structural modifications of the cation, namely the alkyl side chain length and the number of hydroxyethyl groups, as well as the atomic number of the metal anion. Finally, from the magnetic anions evaluated, the [MnCl4]2- is the less toxic. In order to improve the knowledge for the prospective design of environmentally safer MILs, it is important to expand this study to other aquatic organisms at different trophic levels.

CHAPTER 2:The Dissolution of Biomass in Ionic Liquids Towards Pre-Treatment Approach

Fossil resources are no longer regarded as sustainable sources of energy and chemical commodities. The quest for sustainable and environmentally benign sources of energy has become crucial in recent years. Biofuels produced from biomass feedstock derived from plants, such as wood, from by-products of food production and from grasses have been considered to be valuable alternatives as energy sources. However, lignocellulosic feedstock conversion processes are challenging due to their recalcitrant nature to enzymatic or chemical hydrolysis. Pre-treatment of the biomass feedstock is necessary to allow for enzyme digestibility of the cellulosic material present in the plant cell walls. This chapter describes the pre-treatment of biomass based on ionic liquids (ILs). Several parameters that affect biomass pre-treatment using ILs, such as the influence of biomass type, loading and particle size and experimental conditions, and ILs physical properties are disclosed.