Search

Two novel protocols for the chemical valorization of polyhydroxybutyrate (PHB) were developed, aiming at the production of two bio-based molecules: methyl 3-hydroxybutyrate (MHB) and methyl 3-methoxybutyrate (MMB). Optimized reaction conditions were applied to pure PHB and PHB inclusions inside bacterial cells as starting materials. MHB was synthesized through a single-step catalytic methanolysis, while MMB was synthesized through a three-step process: thermolytic distillation to give crotonic acid (CA), esterification to give methyl crotonate (MC), and oxa-Michael addition of MeOH. The obtained MHB and MMB were tested as solvents for the recovery of PHB itself both from freeze-dried single strain cultures (SSC) and mixed microbial cultures (MMC) with low to medium contents of PHB (22-57 wt %). High PHB recovery was achieved: up to 96 ± 1% through MHB and up to 98 ± 1% through MMB. Extraction from MMC slurry (with a PHB content of 39% on dry weight) was also performed, recovering 77 ± 2% using MHB and 92 ± 2% using MMB. High purities and excellent molecular weights and polydispersity indexes of extracted PHB were obtained with both MHB and MMB. Solubility in water, octanol/water partition coefficients (log Kow), and aerobic ready biodegradability of both solvents were also evaluated.

Gels have been recently introduced in conservation to better control the cleaning action. The slow solvent release is of utmost importance to selectively remove varnish layers of a few microns in thickness, applied on paint layers which may have similar chemical properties. To evaluate the interactions of the underlying paint with solvents, diagnostic methods should study the physical and chemical changes that occur during and after the treatment. In this paper, we propose an innovative analytical protocol based on the combination of solid phase microextraction (SPME) and nuclear magnetic resonance (NMR) relaxometry to evaluate solvent entry and retention in the paint layer, as well as the induced microscopic and macroscopic changes to the elasticity of the binder. Moreover, FTIR and optical microscopy are used to evaluate the cleaning efficacy. The proposed analytical protocol can be used to identify solvents or gels which show minimal interaction with the paint. In particular, we have tested the protocol to evaluate the performance of non-toxic and biodegradable green gels on mock-ups and on a painting dated 19th century showing that they perform better than solvents applied with swabs. Five-minute gel treatments were found to be as effective at varnish removal as thirty-second swab treatments following traditional cleaning methods. Cleaning with gels limits the mechanical stress, solvent entry and retention in the paint layer, and reduces the embrittlement due to lower mass transfer. An unusual “sandwich” system was used to avoid the retention of gel residues on the surface with the gels contained in two sheets of Japanese papers – one on top and the other at the bottom.

Organo- and hydrogels have been proposed in the restoration field to treat different types of surfaces. The possibility to retain solvents and to have a controlled and superficial action allowed to use these materials for the removal of very thin layers applied on ancient historical objects, when the under paint layers are particularly delicate and water sensitive. In the last years, an increased attention has been devoted to the proposal of more healthy products to guarantee the safeguard of the operators. Few attention has been devoted to the development of green methods which foresee the use of renewable and biodegradable materials. The aim of this paper is to test a green organo-gel for the cleaning of water sensitive surfaces like varnished egg tempera paintings. The gel has been tested experimented on mock ups varnished with natural and synthetic materials and has been validated on a small portion of a Cimabue painting for the removal of two varnishes applied on two different test areas of the painting.

New formulations based on red grape pomace polyphenols and deep eutectic solvents (DES) have been here evaluated as inhibitors of urease of agricultural interest (jack bean urease, JBU). DES based on choline chloride (CHO) and betaine (BET), combined with ethylene glycol (EG), citric acid (CA), and urea (U), were used both as extracting and carrying agents for polyphenols, becoming active components of the formulations here obtained. Among the various DES combinations, U- and CA-based ones gave the best polyphenol extraction performances, 1.2-1.4-times higher than those of the hydroalcoholic mixture. Among the various DES-polyphenols formulations, the one composed by CHO-EG showed the best antioxidant potential and urease inhibition: 60-90% inhibition of the total JBU activity was achieved with a CHO concentration of 5-20 mM. Good results were also achieved with the BET-EG polyphenol formulation, which was able to inhibit ca. 50% of urease activity at 20 mM concentration of BET. Low phytotoxicity of DES and their polyphenol formulations tested at a concentration of 34 mM of CHO or BET was here observed on cress seedlings and the early growth of oat, in particular, for EG-based DES. On the other hand, tests performed on earthworms showed that CHO-based DES could impair the reproduction, and U-based DES caused severe mortality.

Volatile fatty acids (VFAs) are ideal substrates for mixed microbial cultures to synthesize polyhydroxyalkanoates. Therefore, VFA pertraction from anaerobic diluted fermentation broths to slightly alkaline aerobic medium becomes a crucial step to develop a closed loop concept in which VFAs are used for polyhydroxyalkanoate production. New liquid membranes (LMs) based on lipophilic amines and biodiesel were proposed for this purpose. The performance of each LM was tested through a VFA distribution coefficient test and pertraction kinetic experiments. The transfer of VFAs from LM to receiving solution was the main limiting step of the process, with flux rates of 0.001–0.04 cm3 cm−2 h−1 (best LM with 10 wt% of trioctylamine). The biocompatibility of trioctylamine -biodiesel LM towards anaerobic bacteria was confirmed through a 15-d acidogenic fermentation test. Trioctylamine-biodiesel LM was finally tested in a specifically designed continuous pertraction module, where VFA transfer rates of 1–3 h−1 were achieved.

A transdisciplinary approach that integrates thermochemical conversions and biological transformations for valorizing C-content and chemical energy of anaerobically digested sewage sludge and producing biopolymers (polyhydroxyalkanoates, PHA) and drop-in chemicals (crotonic acid) has been presented here. Hydrothermal carbonization has increased by 10-times the soluble COD of sewage sludge, allowing it to split 44-54% of its COD into an aqueous phase (HTCap) enriched in small fermentable organic molecules; the coupling of acidogenic fermentation and aerobic fermentation converted these substrates first into volatile fatty acids (20% of CODHTCap) and then into PHA (about 20% of CODVFA). The extraction of microbial biomass with dimethyl carbonate (DMC) allowed high quality PHA to be produced, with a high molecular weight (0.9 MDa) and a percentage of medium chain monomers (hydroxyvalerate and hydrohexanoate) close to 12%. The postextraction microbial biomass, still containing a relevant portion of "unextractable" PHA, was last treated at 300 °C to selectively convert the PHA-backbone into crotonic acid with a 42% yield on PHA content basis.

none 9 no Fully biodegradable novel bio-based organogels were developed for removing aged protective films from the surfaces of paintings, aiming at providing effective cleaning tools, easily controllable by reducing the solvent permeation into underlying paint layers and not dangerous for human health and the environment. The gels were based on poly-3-hydroxybutyrate (PHB) as gelling agent, γ-valerolactone (GVL) as solvent and triethyl citrate (TEC) as plasticizer. PHB-gels were able to completely remove protective varnishes on real oil paintings, without affecting the pictorial layer and leaving negligible residues after the application. Moreover, the gels showed good mechanical and handling properties, they were fully composed by non-toxic ingredients and resulted readily biodegradable in water, therefore easily disposable after the use. mixed Samorì, Chiara; Galletti, Paola; Giorgini, Loris; Mazzeo, Rocco; Mazzocchetti, Laura; Prati, Silvia; Sciutto, Giorgia; Volpi, Francesca; Tagliavini, Emilio Samorì, Chiara; Galletti, Paola; Giorgini, Loris; Mazzeo, Rocco; Mazzocchetti, Laura; Prati, Silvia; Sciutto, Giorgia; Volpi, Francesca; Tagliavini, Emilio

none 5 no A new metal-free protocol for promoting oxidation of amines in aqueous-organic medium was developed. NaIO4and TEMPO as the catalyst emerged as the most efficient and selective system for oxidation of differently substituted benzyl amines to the corresponding benzaldehydes without overoxidation. Unsymmetrical secondary amines underwent selective oxidation only at the benzylic position thus realising an oxidative deprotection of a benzylic group with an easy amine recovery. open Galletti, P.*; Martelli, G.; Prandini, G.; Colucci, C.; Giacomini, D. Galletti, P.*; Martelli, G.; Prandini, G.; Colucci, C.; Giacomini, D.

Gorgonian corals play a structural role in temperate and tropical biogenic reefs, forming animal forests and creating biodiversity hot spots. In the Mediterranean Sea, slow-growing and long-lived gorgonian species are threatened by human disturbances and global environmental changes and concern about their conservation is rising. Alkaloid metabolites have proven to be essential in protecting these species from environmental stressors. Traditional profiling methodologies to detect these metabolites require a large quantity of living tissue. Here, the chemodiversity of gorgonian alkaloids was investigated by applying a fast and effective protocol combining extraction and derivatization using small-scale tissue samples and GC/MS analysis. The method was effective in identifying and quantifying alkaloids and guanine-based compounds. Eight N-heterocyclic compounds were found in six Mediterranean gorgonians differing for types and quantity. The metabolomic profile was conservative in species of the Eunicella genus, with three species sharing the same pattern. Conversely, Paramuricea clavata displayed a noticeable spatial pattern of variation among colonies collected in different locations. The analytical approach presented here proved to be effective, allowing rare, endangered, and small-sized species to be screened rapidly for detection of new compounds in order to explore their biological and ecological functions.

none 5 no Surfactants are a wide class of compounds used in a broad spectrum of industrial and everyday applications. In this paper, we present the synthesis of a new family of surfactants having C12 and C18 alkyl chains obtained from itaconic acid and fatty amines, molecules industrially obtained from renewable resources. Main physicochemical properties of synthesized surfactants have been measured and their rheological behaviors have been evaluated at the air-water interface using the pendant drop technique. Some of the synthesized surfactants are stimuli responsive compounds, switchable to a polar form in the presence of CO2. The synthetic strategies have been optimized aiming at the sustainability of the process employing a complete set of green metrics and the software EATOS. none Malferrari, Danilo; Armenise, Nicola; Decesari, Stefano; Galletti, Paola; Tagliavini, Emilio Malferrari, Danilo; Armenise, Nicola; Decesari, Stefano; Galletti, Paola; Tagliavini, Emilio

Microalgae are promising alternative sources of several bioactive compounds that are useful for human applications. However, lipids are traditionally extracted with toxic organic solvents (e.g., mixtures of chloroform and methanol or hexane). In this work, we develop a new lipid extraction protocol for obtaining a fatty-acids-rich extract from the diatom Phaeodactylum tricornutum. Deep eutectic solvents (DESs) and microwaves (MWs) were investigated as pretreatments for environmentally friendly solvent extractions using dimethyl carbonate (DMC) and supercritical CO2 (scCO2). Pretreatments with various DESs formed by choline chloride (ChCl) and different hydrogen-bond donors (oxalic acid, levulinic acid, urea, ethylene glycol, and sorbitol) were tested in combination with DMC extraction. DESs formed by ChCl and carboxylic acids gave the best results, increasing both the selectivity and the total fatty acid (TFA) extraction yield of DMC (by 16% and 80%, respectively). DESs combined with MW heating followed by DMC extraction allowed a TFA yield and fatty acid profile comparable to those of the traditional Bligh and Dyer extraction method to be reached, along with a much better selectivity (88% vs 35%). This pretreatment was also demonstrated to significantly improve the extraction efficiency of scCO2, increasing the TFA yield by a factor of 20 and providing highly purified triglyceride extracts.

An efficient and practical chemo-enzymatic aerobic oxidation in water of benzylamines to obtain aldehydes or imines is described. Laccase from Trametes versicolor was chosen as biocatalyst, and TEMPO (radical 2,2,6,6-tetramethylpiperidine 1-oxyl) as mediator. A study on the pH dependence of the aqueous medium allowed us to realise a fine tuning on product selectivity. Under our optimized reaction conditions, the bio-oxidation of a series of primary, secondary and cyclic amines has been achieved

Analysis of artworks and identification of their molecular components are of utmost importance for selecting proper conservation strategies and monitoring restoration. Accordingly, development of simple and readily applicable paint analysis assays is highly sought in conservation science and technology. We prepared transparent spin-coated films comprising polydiacetylene (PDA) derivatives upon poly(methyl methacrylate) (PMMA) substrates and employed the PDA/PMMA films for color analysis of organic constituents in painting materials. We show that distinct color transformations were recorded upon addition of paint compounds to different PDA films. Quantitative analysis revealed that the colorimetric transitions were dictated by the interactions between the diacetylene headgroups and the tested compounds. This study underscores the significance of the diacetylene headgroup for molecular discrimination and points to the possible uses of the PMMA-supported PDA films for colorimetric screening of organic components in painting materials.

Pyrrolidinium imides are considered among the most promising electrolytes for the development of novel and sustainable portable energy devices. Because of this widespread potentiality, a risk scenario of an erroneous disposal of ionic liquids-based batteries in the environment has to be taken into account. In the present study, some of the best energy performing pyrrolidinium-based ionic liquids were evaluated in terms of persistence in aquatic environments and hazard toward freshwater organisms (crustacean Daphnia magna and unicellular green alga Raphidocelis subcapitata). The examined ionic liquids were not aerobically biodegradable (biodegradation less than 5% in 28 days), but they demonstrated low toxicity toward algae and crustaceans, according to the standard bioassay end points (EC50 > 100 mg L-1). However, ionic liquids were able to alter the cellular morphology of R subcapitata and an increased amount of proteins (30%) was observed in the exposed cells, suggesting an inhibition of cellular division.

Temperature-dependent selectivity in nucleophilic additions is affected by the solvent. The inversion temperature (marked with arrows in the graph) that appears in the nonlinear Eyring plots of ln (anti/syn) versus temperature for the addition of butyllithium to an O-protected alpha-hydroxy aldehyde 1 does not depend on nucleophiles (nBuLi (black triangle), tBuLi (*)), but on the solvent. Its value can be obtained from a plot of the (13)C NMR chemical shift of C=O versus temperature. TBDMS=tBuMe(2)Si.

Solvent and temperature effects on facial diastereoselectivity of nucleophilic addition have been long observed but often neglected. Temperature dependent measurements according to the modified Eyring equation allow the evaluation of stereoselectivity in terms of differential enthalpy and entropy of activation, and demonstrate the paramount importance of entropic contribution in directing the facial diastereoselectivity. Even the reaction solvent proved to be important in determining the isomer ratio. In many cases Eyring plots show a non-linear behavior consisting of two linear regions intersecting at a point called the inversion temperature (Tinv) which, for the same reaction, depends on the nature of the solvent and correlates with their melting points. We propose that Tinv is the temperature value for the interconversion between two different solvation clusters which should behave like two different molecules.

New polyethoxylated tertiary amines were synthesised and applied as Switchable Hydrophilicity Solvents (SHS) in the extraction and recovery of lipids from algal cultures, bypassing harvesting and de-watering steps. The eco-toxicological profile of the new amines was explored by evaluating their potential in inhibiting algal growth, and deepened by measuring the acute toxicity towards the crustacean Daphnia magna and the ready biodegradability in water. Among the synthesised amines, the one bearing two ethoxy units, named amine 2, showed the best combination in terms of lipids' extractive performances and toxicity; therefore it could be considered as a good alternative to N,N-dimethylcyclohexylamine (DMCHA), at the moment the most studied and effective SHS. © 2014 The Royal Society of Chemistry.

New β-lactam compounds containing a bis(indolyl)-framework were synthesized. The key step in the synthetic strategy was a nucleophilic addition of unprotected indole to a suitable butyl aldehyde anchored on the C-4 side chain of azetidinone intermediates. The use of an ionic liquid as reaction medium allowed the use of a catalytic amount of Dy(OTf)3 for the nucleophilic addition and facilitated the isolation of the product.

Stereoselectivity is a major topic in organic synthesis. Intensive investigations into the role of solvents on diastereo- and enantioselective reactions, as well as temperature-dependent measurements of diastereomeric and enantiomeric ratios, have shed light on the existence of dynamic solvation effects. In this tutorial review, several examples of non-linear Eyring plots in stereoselective nucleophilic additions, cycloadditions, photochemical and enzymatic reactions are reported. Experimental data and spectroscopic analyses obtained in aliphatic and aromatic hydrocarbons, halohydrocarbons, ethers and mixtures lead to the formulation of a hypothesis on the inversion temperature phenomenon as being due to an equilibrium between distinct solute–solvent clusters, which are the real reactive species in solution.

Furan-containing quaternary ammonium iodides, bis(trifluoromethane)sulfonimides, and tetrafluoroborates are obtained in good overall yield with mild operation conditions starting from furfural, a cheap chemical substance obtainable from crop residue feedstocks. The application of these new ion pairs can be envisioned in the fields of ionic liquid solvents, of surfactants and of biocides in analogy with benzyl quaternary ammonium salts. In view of practical applications, the determination of the thermal properties of new ion pairs together with preliminary ecotoxicological evaluation of some representative products has also been performed.

Aerobic biodegradation of ionic liquids in soil was monitored for the first time. The tests, followed over six months according to ASTM D 5988-96, were carried out on the four ionic liquids obtained from 1-R-3-methylimidazolium cations, with R=CH(3)(CH(2))(3) and CH(3)O(CH(2))(2), and the tetrafluoroborate and dicyanamide counter anions. The n-butyl derivatives, after an induction period of about two months, were found to be degradable, although the degradation rate with the dicyanamide anion was smaller. In contrast, no significant production of CO(2) was observed in the tests with the methoxyethyl derivatives. Calculations at the B3LYP/6-31G(d) level were carried out to characterize the atomic charge distributions and frontier orbital structures of 1-alkyl-3-methylimidazolium cations and point out the changes caused by replacement of a CH(2) group of the alkyl chain with an oxygen atom. The calculations predict an overall negative charge on the nitrogen atoms of the imidazolium-based cations. The energies of the highest occupied (pi) MO and lowest empty (pi( *)) MO are only slightly perturbed by the length and nature of the alkyl chain. However, the electron-donor properties of the oxy derivatives are radically increased. The HOMO becomes a lone pair orbital mainly localized on the oxygen atom, and its ionization energy is sizeably smaller than that of the outermost ring pi MO.

Novel 4-alkylidene-beta-lactams with a polyphenolic side chain were synthesized and evaluated as radical scavengers. We have undertaken a detailed study of the antioxidant activity in vitro with chemical and biological testing of the new beta-lactams and of the corresponding methyl polyhydroxy benzoates. Antioxidant activity of beta-lactams and methyl benzoates was measured with the Briggs-Rauscher oscillating reaction, the TEAC (Trolox((R)) Equivalent Antioxidant Capacity) assay, and as ability to inhibit ROS (=Reactive Oxygen Species) production on myoblast H9c2 cells. The results were discussed with regard to mechanism and correlated with structural parameters.

This work is concerned with the rationalization and prediction of solvent and temperature effects in nucleophilic addition to alpha-chiral carbonyl compounds leading to facial diastereoselectivity. We study, using molecular dynamics simulations, the facial solvation of (R)-2-phenyl-propionaldehyde in n-pentane and n-octane at a number of temperatures and compare it with experimental selectivity data for the nBuLi addition leading to syn- and anti-(2R)-2-phenyl-3-heptanol, which give nonlinear Eyring plots with the presence of inversion temperatures. We have found from simulations that the facial solvation changes with temperature and alkane. Moreover, by introducing a suitable molecular chirality index we have been able to predict break temperatures (T(CI)) for the two solvents within less than 20 degrees of the inversion temperatures experimentally observed in the diastereoselective nBuLi addition. We believe this could lead to a viable approach for predicting inversion temperatures and other subtle solvent effects in a number of stereoselective reactions.

Eyring plots of lnE vs. 1/T show inversion temperature in kinetic resolution by lipases, demonstrating that clustering effects in the substrate solvation manage the enzymatic selectivity.

The enantioselective synthesis of (2S)-2-phenylpropanol and (2S)-2-(4-iso-butylphenyl)propanol ((S)-Ibuprofenol) has been achieved by means of Horse Liver Alcohol Dehydrogenase (HLADH) in buffered aqueous solution or buffered organic solvent mixtures; under the reaction conditions, a dynamic kinetic resolution (DKR) process was realized with good reaction yields and enantiomeric ratios.