The impressive pharmacological properties shown by a number of coumarins have led to extraordinarily large emphasis being placed on the design of more efficient and greener synthetic procedures to ...produce them. The increasing use of enabling technologies, such as microwaves, ultrasound, new heterogeneous catalysts and greener solvents in recent years has made access to coumarin derivatives much simpler. This review will highlight the most recent synthetic advances that make use of non-conventional methods and energy sources and some perspectives for the future, in particular the synthesis of new hybrid molecules bearing a coumarin moiety with a dual mode of biological action.
The impressive pharmacological properties shown by a number of coumarins have led to extraordinarily large emphasis being placed on the design of more efficient and greener synthetic procedures to produce them.
Glycerol has the potential to be both an excellent renewable solvent in modern chemical processes and a versatile building block in biorefineries. Both of these potential applications may be made ...easier and more convenient by microwave and/or ultrasound irradiation. As glycerol is a nontoxic, biodegradable compound, it will provide important environmental benefits to new platform products. Furthermore, significant markets in polymers, polyethers, fuel additives, nanoparticles and other valuable compounds may well be opened up by cutting down the high purification cost of glycerol. The aim of this review is to highlight the best literature examples of glycerol being used, either as a solvent or as a reagent, to give interesting results under microwave or ultrasound irradiation.
Glycerol has the potential to be both an excellent renewable solvent in modern chemical processes and a versatile building block in biorefineries.
The functionalization of single-walled carbon nanotubes (SWCNTs) via microwave-assisted grafting reactions enables efficient multidecoration in a single step. A novel water-soluble SWCNT platform was ...prepared via the simple 1,3-dipolar cycloaddition of azomethine ylides under dielectric heating. Thanks to a single grafting reaction the CNT surface binds in a 1 : 1 ratio an amino acidic β-cyclodextrin (β-CD) derivative and the DOTAMA moiety (1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid monoamide). This novel "one shot" synthesis, compared with multistep functionalizations, preserves the SWCNT's structural integrity (TEM images). Besides thermogravimetric analyses, the determination of the amount of β-CD and DOTA moieties grafting onto the SWCNT's surface was performed on the basis of phenolphthalein and gadolinium complexation, respectively.
New highly soluble β-aminoalcohol β-cyclodextrin (β-CD) derivatives have been synthesized via nucleophilic epoxide opening reactions with mono-6-amino mono-6-deoxy-permethyl-β-CD and mono-6-amino ...mono-6-deoxy-β-CD. The binding properties of the β-CD were enhanced by linking aminoalcohol subunits which caused its solubility to improve markedly. The reaction conditions were optimised using microwave irradiation giving moderate-to-good yields with a series of epoxides. A regioselective epoxide opening reaction was observed in the reaction with styrene oxide while the stereoselectivity was strictly dependent on substrate structure.
The so-called ''enabling techniques'' can dramatically promote the synthesis of
N
-heterocycles. Besides facilitating very quick cyclization, these technologies bring with them process ...intensification, safer protocols, cost reduction, energy savings, and waste minimization. We herein describe a series of efficient N-heterocycle cyclizations carried out under microwave and/or ultrasound irradiation.
The intensification of chemical processes, which means improving their efficiency and cutting down energy consumption, requires more automation and non-conventional energy sources, as well as new, ...efficient and scalable protocols which need to be implemented in continuous flow reactors. We showed that flowing systems are advantageous when using conductive heating or non-conventional energy sources such as microwave (MW) and ultrasound (US) irradiation. We developed several hybrid flow reactors suitable for organic reactions with the aim of optimizing heat and mass transfer and achieving process intensification. Here we present a series of applications of a simple flow reactor that uses an HPLC pump, a column heater and suitable columns filled with a supported catalyst. Using the same column packed with a commercially available derivatized acidic silica we efficiently performed two reaction types: the nucleophilic opening of epoxides with a series of alcohols and the Friedländer quinoline synthesis. In both cases we obtained pure products in excellent yield in a few minutes. The set of experiments on the epoxide opening could be repeated on a hybrid flow reactor under sequential MW/US irradiation, though at lower temperature. A suitable combination of 1D and 2D NMR experiments (i.e.
1H–
13C HMQC,
1H–
1H COSY and
1H–
1H NOESY) was applied to unambiguously assign the stereochemistry of hydroxyethers from the nuclephilic cleavage of limonene oxide.
The geopolitics of the European Green Deal Leonard, Mark; Pisani-Ferry, Jean; Shapiro, Jeremy ...
International Organisations Research Journal,
01/2021, Letnik:
16, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The European Green Deal is a plan to decarbonise the EU economy by 2050, revolutionise the EU’s energy system, profoundly transform the economy and inspire efforts to combat climate change. But the ...plan will also have profound geopolitical repercussions. The Green Deal will affect geopolitics through its impact on the EU energy balance and global markets; on oil and gas-producing countries in the EU neighbourhood; on European energy security; and on global trade patterns, notably via the carbon border adjustment mechanism. At least some of these changes are likely to impact partner countries adversely. The EU needs to wake up to the consequences abroad of its domestic decisions. It should prepare to help manage the geopolitical aspects of the European Green Deal. Relationships with important neighbourhood countries such as Russia and Algeria, and with global players including the United States, China and Saudi Arabia, are central to this effort, which can be structured around seven actions: 1) Help neighbouring oil and gas-exporting countries manage the repercussions of the European Green Deal. The EU should engage with these countries to foster their economic diversification, including into renewable energy and green hydrogen that could in the future be exported to Europe; 2) Improve the security of critical raw materials supply and limit dependence, first and foremost on China. Essential measures include greater supply diversification, increased recycling volumes and substitution of critical materials; 3) Work with the US and other partners to establish a ‘climate club’ whose members will apply similar carbon border adjustment measures. All countries, including China, would be welcome to join if they commit to abide by the club's objectives and rules; 4) Become a global standard-setter for the energy transition, particularly in hydrogen and green bonds. Requiring compliance with strict environmental regulations as a condition to access the EU market will be strong encouragement to go green for all countries; 5) Internationalise the European Green Deal by mobilising the EU budget, the EU Recovery and Resilience Fund, and EU development policy; 6) Promote global coalitions for climate change mitigation, for example through a global coalition for the permafrost, which would fund measures to contain the permafrost thaw; 7) Promote a global platform on the new economics of climate action to share lessons learned and best practices.
Energy in Africa Hafner, Manfred; Tagliapietra, Simone; de Strasser, Lucia
2018
eBook
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This open access book presents a picture of the current energy challenges on the African continent (and the Sub-Saharan region in particular) and proposes pathways to an accelerated energy ...transition. Starting with an analysis of the status quo and the outlook for Africa’s energy demand and energy access, it provides an account of the available resources, including hydrocarbons and renewable energy resources, which are playing an increasingly crucial role. It then moves on to analyze the level of investment required to scale-up Africa’s energy systems, shedding light on the key barriers and elaborating on potential solutions. It also provides a suggestion for improving the effectiveness of EU–Africa cooperation. While mainly intended for policymakers and academics, this book also speaks to a broader audience interested in gaining an overview of the challenges and opportunities of the African energy sector today and in the future.
We have developed a general, two-step protocol for the synthesis of chiral non-racemic coumarin anticoagulants (e.g. warfarin, coumachlor and acenocoumarol). This approach features a one-pot ...three-component tandem Knoevenagel–hetero-Diels–Alder reaction between in situ generated 3-arylidene-2,4-chromanediones and
iso-propenyl ether derived from (−)-menthol.
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