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Hydrothermal carbonization (HTC) serves as a sustainable method to transform pine needle waste into nitrogen-doped (N-doped) hydrochars. The primary focus is on evaluating these hydrochars as catalytic electrodes for the oxygen reduction reaction (ORR) and carbon dioxide reduction reaction (CO2RR), which are pivotal processes with significant environmental implications. Hydrochars were synthesized by varying the parameters such as nitrogen loading, temperature, and residence time. These materials were then thoroughly characterized using diverse analytical techniques, including elemental analysis, density measurements, BET surface area analysis, and spectroscopies like Raman, FTIR, and XPS, along with optical and scanning electron microscopies. The subsequent electrochemical assessment involved preparing electrocatalytic inks by combining hydrochars with an anion exchange ionomer (AEI) to leverage their synergistic effects. To the best of our knowledge, there are no previous reports on catalytic electrodes that simultaneously incorporate both a hydrochar and AEI. Evaluation metrics such as current densities, onset and half-wave potentials, and Koutecky–Levich and Tafel plots provided insights into their electrocatalytic performances. Notably, hydrochars synthesized at 230 °C exhibited an onset potential of 0.92 V vs. RHE, marking the highest reported value for a hydrochar. They also facilitated the exchange of four electrons at 0.26 V vs. RHE in the ORR. Additionally, the CO2RR yielded valuable C2 products like acetaldehyde and acetate. These findings highlight the remarkable electrocatalytic activity of the optimized hydrochars, which could be attributed, at least in part, to their optimal porosity. [ABSTRACT FROM AUTHOR]

The use and consumption of electrodes is a crucial aspect regarding the overall efficiency and sustainability of electrochemical reactions. When metal electrodes are used, the cost of the material combined with the processing costs assumes relevance in terms of economics and sustainability. Herein we report a case study that aims to define an electrochemical synthetic protocol using electrodes prepared from recovered aluminium scrap. We approached the problem by evaluating and comparing the different carbon footprints associated with the use of different electrode materials from primary sources and secondary (recycled) sources. We optimized the use of electrodes made from secondary aluminium to develop a simple, oxidant-free protocol for the representative synthesis of 2-oxazolines from amino alcohols and aldehydes using generally elusive concentrated conditions and a recoverable reaction media. A further evaluation of the developed process using green metrics allowed us to quantify the waste distribution of our procedure in comparison with the literature processes as well as the progress in terms of sustainability and intrinsic reaction efficiency. [ABSTRACT FROM AUTHOR]

We herein report a waste-minimized process for the synthesis of iodinated hexa-aryl borazines in different iodination patterns and amounts. Access to these widely promising B–N-containing materials features several synthetic challenges including low solubility, narrow stability/reactivity, and limited selectivity. Therefore, the development of synthetic procedures also faces evident sustainability challenges. We have tackled these aspects by merging unconventional activation techniques with metrics-oriented synthetic design. Herein, we report a protocol that enables a fast access route to iodinated borazines which are useful substrates to access different post-functionalized more complex materials. The protocol uses simple and benign chemicals, is waste minimized (E-factor 2.79), and produces iodinated hexa-aryl borazines in good to excellent yields. An evaluation of green metrics, including EcoScale, is provided to quantify the advantages associated with the newly defined protocol. [ABSTRACT FROM AUTHOR]

The necessary use of large amounts of a homogeneous electrolyte represents a major issue and challenge for the whole sustainability of electrosynthetic procedures. Herein, we report the use of a solid ammonium salt (e.g. Amberlyst-400-Cl, Amb-400-Cl) as a reusable electrolyte with excellent performance in the representative electrosynthesis of 2-arylbenzoxazoles. Amb-400-Cl works efficiently without adding any additional supporting electrolytes or mediators, and it can be reused without the need for a regeneration procedure. Exploiting this finding, a sustainable electro-promoted protocol has been developed under batch and flow conditions, which proves that the reported chemical and technological innovation leads to significant improvements compared to the literature processes. Extensive green metrics analysis has also been reported to fully quantify the advances in terms of sustainability. [ABSTRACT FROM AUTHOR]

We have defined a procedure for the late‐stage functionalization of aryl borazines to facilitate the synthesis of a diverse array of borazine derivatives with varying substitution patterns, paving the way for further exploration of the field. More in detail, we have studied and disclosed a simple iodination procedure that could be applied to several differently substituted substrates (1 a–i) with mostly good to excellent yields (47–96%). The representative iodinated compounds 2 b and 2 e, were utilized to test their use in further representative functionalization steps such as cyanation, Heck, and Sonogashira reactions. All products 3 a–e were obtained in satisfactory good to very good yields considering the multiple (three or six times) concomitant reactions. [ABSTRACT FROM AUTHOR]

Carbon-to-carbon (C–C) cross-coupling reaction (CCR) protocols represent a major breakthrough in synthetic chemistry. These innovative CCRs are widely applied in medicinal chemistry to produce a multitude of drugs, as well as in many other applied sciences. Despite strong efforts to implement green chemistry principles in synthetic chemistry, only individual outcomes for (many) single reactions with single synthesis protocols have been reported, and a comprehensive view of the environmental value of major chemical breakthroughs is lacking in the literature. This study concerns the life cycle assessment (LCA) of CCRs, which were awarded the Nobel Prize in 2010. The required materials were obtained from datasets based on industrial data, while the analysed compounds and target products from C–C coupling reaction protocols were modelled based on laboratory-scale experimental data (the only data available), and the use of electrical power was assumed. We discovered that it is essential to separate intrinsic and extrinsic impacts to allow focus on delivering a generic sustainability view. The former are the genuine generalizable innovations of the novel chemical process method, and are worth improving via LCA. The latter are outcomes of individual laboratory chemical protocols, which are aimed at achieving chemical innovation but typically not at holistically optimising the environmental profile, with a limited scope for LCA prediction. In terms of the intrinsic value of the Nobel Prize CCRs, we determined the environmental profile for variations of the (1) CCR catalyst, (2) CCR halobenzene, and (3) CCR ligand, all of which are constitutional innovations of the chemical protocols of the 2010 Nobel Prize in Chemistry. The findings indicate that (1) the catalyst should be recycled, as its footprint is far too dominating; (2) the halobenzene should be chosen carefully to balance its intrinsic ('backpack') and extrinsic (yield, catalyst choice) impacts; and (3) the ligand should be recycled in the context of the catalyst recycling. As demonstrated herein, the value of LCA is to provide predictions for future improvements ('anticipatory or ex-ante LCA') and to assure the best leverage of environmental gains that can readily be achieved for major chemical innovations, as exemplified by the 2010 Nobel Prize in Chemistry. [ABSTRACT FROM AUTHOR]

The conversion of levulinic acid (LA) into alkyl levulinates is highly significant due to the wide range of applications for these products, including their use as fuel additives, solvents, and fragrances. In order to meet the growing need for environmentally friendly chemical production, this study takes a circular economy approach by upcycling a common urban waste, i.e., pine needles, to synthesize a robust heterogeneous acid catalyst, subsequently used to efficiently upgrade LA into levulinates. By utilizing a single-step procedure under mild operating conditions, the resulting PiNe-SO3H catalyst demonstrated good performances and flexibility in synthesizing diverse bio-derived levulinates. In fact, the catalyst showed an exceptionally broad range of applicability, resulting in isolated yields ranging from 46% to 93%, which is an unprecedented achievement. The catalyst's ability to be reused was tested, revealing remarkable performance for up to 10 consecutive cycles with negligible loss in efficiency. Additionally, a significant focus was directed towards developing a method that minimizes waste during the isolation process. This involved optimizing reaction conditions and rationalizing work-up procedures, resulting in low Environmental factor (E-factor) values ranging from 1.2 to 8.9. To comprehensively assess the overall environmental sustainability of the process, various additional green metrics were calculated, and the Ecoscale tool was employed as well. Furthermore, mechanistic investigations elucidated the favored reaction pathway, underscoring that, under the optimized conditions, the prevailing mechanism entails direct esterification, as opposed to the generation of a pseudo-ester intermediate. [ABSTRACT FROM AUTHOR]

The landscape of organic synthesis has changed in the last two decades, especially in areas such as pharmaceutical synthesis and large-scale industrial synthesis. The progress and development of synthetic methodologies together with increasing attention to environmental and safety problems, have led many researchers to study procedures that could be compatible with the sustainable development of industrial production. Until a few years ago, the production of APIs was substantially dominated by reliable and solid chemistry but which nevertheless attracted some criticism from the point of view of the length of the synthetic procedures in terms of steps, and therefore in terms of waste production. In recent years, however, we have been witnessing the adoption, even by large industrial groups, of step-economical methodologies based on direct C–H functionalization reactions which, compared to reactions such as cross-coupling or aromatic nucleophilic substitutions, promise better sustainaibility as they do not require pre-functionalized substrates, and therefore offer the intriguing possibility of reducing the number of steps to attain the target. This review presents exemplary case studies analyzed holistically on the basis of waste production (E-factor) and on the basis of environmental and safety hazard scores (ES and SHS scores) with the aim of quantifying whether the adoption of direct C–H functionalization technology is actually always the most effective strategy compared to classic approaches. It will, therefore, ultimately give the reader a quantitative evaluation of how promising in terms of sustainability the current direction of chemical production actually is compared to previous methodologies. [ABSTRACT FROM AUTHOR]

A series of halogenated systems for pyrazolo[1,5-a]pyrimidines have been developed. Selective transformations of pyrazolo[1,5-a]pyrimidines by mono- and di-iodination were achieved by varying the ratio of pyrazolo[1,5-a]pyrimidines to NIS. In addition, the reaction of pyrazolo[1,5-a]pyrimidines with NBS or NCS uniquely gave dibrominated or dichlorinated products. The wide range of substrates, good functional group tolerance and gram-scale synthesis further demonstrate the application potential of this reaction. This work provides an efficient method for the construction of structurally diverse halogenated pyrazolo[1,5-a]pyrimidine derivatives. [ABSTRACT FROM AUTHOR]