Dimethyl isosorbide via organocatalyst N-methyl pyrrolidine: scaling up, purification and concurrent reaction pathways

Dimethyl isosorbide (DMI) is a green replacement for conventional dipolar solvents as dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) that are toxic and dangerous for human and environmental health. DMI is one of the simplest derivatives well-known bio-based platform chemical isosorbide, an anhydro sugar readily synthesised by D-sorbitol dehydration reaction. [1] The synthesis of DMI is mainly based on the etherification of bio-based platform chemical isosorbide in the presence of basic or acid catalyst employing different alkylating agent. Among them, dimethyl carbonate (DMC) is relevant thanks to its haracteristics: good biodegradability and low toxicity. [2] In this work, we report an extensive investigation on highly yielding methylation of isosorbide via DMC chemistry promoted by several nitrogen organocatalyst. [3] Reaction conditions were performed and then applied for the methylation of isosorbide epimers - isomannide and isoidide - and for preliminary scale-up test (10 g of isosorbide). Pure DMI, starting from mixture reaction, was obtained by both column chromatography and distillation at reduced pressure. Between all nitrogen used, N-methyl pyrrolidine (NMPy) demonstrated excellent behaviour as catalyst also for the one-pot conversion of D-sorbitol into DMI. Furthermore, for the first time, all seven methyl and carboxymethyl intermediates - observed during the etherification of isosorbide - were synthetized, isolated and characterised. This study allowed us to know more deeply the concurrent reaction pathways (methylation, methyl carbonylation and decarboxylation) leading to DMI and on the role played by NMPy in the methylation of isosorbide and in this way to propose a mechanism of conversion into isosorbide into DMI via DMC chemistry

Catalytic heterogeneous route for the synthesis of dimethyl isosorbide using dimethyl carbonate as methylating agent

In this contribution a heterogeneous catalytic route is envisaged by using as catalyst MgAlOx mixed oxides derived from hydrotalcite thermally treated (Mg/Al molar ratio of 3). The complete conversion of isosorbide is accomplished within the first hour but the DMI is not observed until 7 hours of reaction and its yield increases up to 100% after 24 hours of time on stream. The reutilization of the catalyst has shown a decline in DMI yield up to 52% after 4 runs even though the isosorbida conversion was of 100%.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Alkyl Levulinates from Furfuryl Alcohol Using CT151 Purolite as Heterogenous Catalyst: Optimization, Purification, and Recycling

Commercially available Purolite CT151 demonstrated to be an efficient acid catalyst for the synthesis of alkyl levulinates via alcoholysis of furfuryl alcohol (FA) at mild temperatures (80–120 °C) and short reaction time (5 h). Reaction conditions were first optimized for the synthesis of ethyl levulinate and then tested for the preparation of methyl-, propyl-, isopropyl-, butyl, sec-butyl- and allyl levulinate. Preliminary scale-up tests were carried out for most of the alkyl levulinates (starting from 5.0 g of FA) and the resulting products were isolated as pure by distillation in good yields (up to 63%). Furthermore, recycling experiments, conducted for the preparation of ethyl levulinate, showed that both the Purolite CT151 and the exceeding ethanol can be recovered and reused for four consecutive runs without any noticeable loss in the catalyst activit

Dialkyl Carbonates as Sacrifical Molecules: from Heterocycles to Macrocycles

Dialkyl carbonate (DACs) are well recognized green reagents and solvents for new synthetic pathways. In particular dimethyl carbonate (DMC), nowadays synthesized by CO2 insertion into epoxides, has shown surprising high selectivity with different nucleophiles acting either as methoxycarbonylation (BAc2 mechanism) or methylaing (BAl2 mechanism) agent. In this lecture recent advances in DMC chemistry for chlorine-free synthesis of five- and six-membered heterocycles will be presented. Reaction of 1,4-diols with DMC in the presence of a base resulted in the chlorine-free synthesis of five-membered cyclic compounds. This synthetic procedure can be also used for the quantitative intramolecular heterocyclisation of bifunctional compounds, i.e., 4-amino-1-butanol to achieve pyrrolidine. Six-member cyclic carbamates have also been synthesized by chlorine-free approach employing DMC chemistry. In fact, reacting a primary amine or a hydrazine with a di(methylcarbonate) derivative of 1,3-diols oxazinan-2-ones can be synthesized in a one-pot chlorine-free reaction. Recently we also investigated the replacement of the chlorine by a carbonate moiety in half-nitrogen and -sulphur mustard compounds. Results collected demonstrated that the novel mustard carbonates are easily synthesized, don’t show any toxicity and react with a wide range of nucleophiles in the absence of any base. These novel compounds can be employed for the synthesis of piperidines and thiopyrans. Furthermore, the polycondensation of a nitrogen mustard carbonate analogue with aromatic diols under dilution conditions resulted in a new synthetic approach to azacrowns previously not accessible

Brain interaction during cooperation: Evaluating local properties of multiple-brain network

Subjects’ interaction is the core of most human activities. This is the reason why a lack of coordination is often the cause of missing goals, more than individual failure. While there are different subjective and objective measures to assess the level of mental effort required by subjects while facing a situation that is getting harder, that is, mental workload, to define an objective measure based on how and if team members are interacting is not so straightforward. In this study, behavioral, subjective and synchronized electroencephalographic data were collected from couples involved in a cooperative task to describe the relationship between task difficulty and team coordination, in the sense of interaction aimed at cooperatively performing the assignment. Multiple-brain connectivity analysis provided information about the whole interacting system. The results showed that averaged local properties of a brain network were affected by task difficulty. In particular, strength changed significantly with task difficulty and clustering coefficients strongly correlated with the workload itself. In particular, a higher workload corresponded to lower clustering values over the central and parietal brain areas. Such results has been interpreted as less efficient organization of the network when the subjects’ activities, due to high workload tendencies, were less coordinated

Catechol-based macrocyclic aromatic ether-sulfones: Synthesis, characterization and ring-opening polymerization

Cyclocondensation between 4,4`-bis(4-chlorobenzenesulfonyl)biphenyl and catechol, with subsequent chromatographic separation of the reaction products, led to the isolation of four novel ether-sulfone macrocycles (cyclic dimer, -trimer, -tetramer and -pentamer). Similarly, cyclocondensation of catechol with a novel seven-ring diketone/disulfone monomer allowed the isolation of the two new aromatic ether-ketone-sulfone macrocycles, a cyclic monomer and a cyclic dimer. Transannular shielding and deshielding effects in the cyclic monomer produce substantial chemical shift differences for chemically equivalent protons in the 1H NMR spectra of the cyclic monomer and -dimer. Fluoride-initiated ring-opening polymerization of the ether-sulfone cyclic trimer affords a novel, high-molecular weight poly(ether-sulfone)

Toward domotic appliances control through a self-paced P300-based BCI

During recent years there has been a growing interest in Brain Computer Interface (BCI) systems as an alternative means of interaction with the external world for people with severe motor disabilities. The use of the P300 event-related potentials as control feature allows users to choose between various options (letters or icons) requiring a very short calibration phase. The aim of this work is to improve performances and flexibility of P300 based BCIs. An efficient BCI system should be able to understand user's intentions from the ongoing EEG, abstaining from doing a selection when the user is engaged in a different activity, and changing its speed of selection depending on current user's attention level. Our self-paced system addresses all these issues representing an important step beyond the classical synchronous P300 BCI that forces the user in a continuous control task. Experimentation has been performed on 10 healthy volunteers acting on a BCI-controlled domestic environment in order to demonstrate the potential usability of BCI systems in everyday life. Results show that the self-paced BCI increases information transfer rate with respect to the synchronous one, being very robust, at the same time, in avoiding false negatives when the user is not engaged in a control task

Neurophysiological Profile of Antismoking Campaigns

Over the past few decades, antismoking public service announcements (PSAs) have been used by governments to promote healthy behaviours in citizens, for instance, against drinking before the drive and against smoke. Effectiveness of such PSAs has been suggested especially for young persons. By now, PSAs efficacy is still mainly assessed through traditional methods (questionnaires and metrics) and could be performed only after the PSAs broadcasting, leading to waste of economic resources and time in the case of Ineffective PSAs. One possible countermeasure to such ineffective use of PSAs could be promoted by the evaluation of the cerebral reaction to the PSA of particular segments of population (e.g., old, young, and heavy smokers). In addition, it is crucial to gather such cerebral activity in front of PSAs that have been assessed to be effective against smoke (Effective PSAs), comparing results to the cerebral reactions to PSAs that have been certified to be not effective (Ineffective PSAs). &e eventual differences between the cerebral responses toward the two PSA groups will provide crucial information about the possible outcome of new PSAs before to its broadcasting. &is study focused on adult population, by investigating the cerebral reaction to the vision of different PSA images, which have already been shown to be Effective and Ineffective for the promotion of an antismoking behaviour. Results showed how variables as gender and smoking habits can influence the perception of PSA images, and how different communication styles of the antismoking campaigns could facilitate the comprehension of PSA’s message and then enhance the related impac