Herein, we report
the development of a tailor-made fluoride-based
heterogeneous catalyst, POLITAG-F, for the waste-minimized
continuous production of cyanohydrin silyl ethers. The careful designing
of the polymeric support and the choice of fluoride ion as the anionic
species resulted in the improvement of catalytic efficiency and allowed
the effective conversion of different carbonyls (aldehydes, ketones,
and unsaturated ketones). The POLITAG-F catalyst, employed
under flow conditions, led to the conversion of large amounts (over
100 mmol) of the substrate with a productivity of 0.1 mmol min–1. In addition, flow conditions allowed to minimize
the waste production reaching an associated E-factor
value of 0.04. An exhaustive evaluation of the environmental impact
of our protocol has been reported by considering several green metrics
(process mass intensity, atom economy, and reaction mass efficiency)
and also the benign index and the safety hazard index of the process.
Valorisation of phenols into high value-added products via step- and atom-efficient protocols is of great importance for the transition to sustainable chemical production. Among the transformation of phenols, C–H functionalization...
We herein report a multi-step flow protocol for the synthesis of 1,4-disobstitued 1,2,3-triazoles starting from α,β-unsaturated carbonyls. Best results both in terms of chemical productivity and sustainability were obtained using...
Organic solvents are ubiquitous in most of the synthetic processes and play a crucial role in influencing the chemical behavior of catalytic system and/or reactive species. Modern chemistry inevitably includes an evaluation of the chemical efficiency and the environmental impact of a desired procedure. CH functionalization processes represent an important advance in terms of chemical efficiency to form new CC and CX bonds, and also for this type of transformation there is a great deal of interest for the use of safer/greener solvents that could replace the classic toxic ones. In this article, the current state of the art on the use of greener solvents as media for accessing chemically and environmentally efficient protocols for CH functionalization processes is summarized.
We herein report a waste minimization protocol for the
β-azidation
of α,β-unsaturated carbonyl compounds using TMSN3. The selection of the appropriate catalyst (POLITAG-M-F), in combination with the reaction medium, resulted in enhanced
catalytic efficiency and a low environmental footprint. The thermal
and mechanical stability of the polymeric support allowed us to recover
the POLITAG-M-F catalyst for up to 10 consecutive runs.
The CH3CN:H2O azeotrope has a 2-fold positive
effect on the process, increasing the efficiency of the protocol and
minimizing waste generation. Indeed, the azeotropic mixture, used
as a reaction medium and for the workup procedure, was recovered by
distillation, leading to an easy and environmentally friendly procedure
for product isolation in high yield and with a low E-factor. A comprehensive
evaluation of the environmental profile was performed by the calculation
of different green metrics (AE, RME, MRP, 1/SF) and a comparison with
other literature available protocols. A flow protocol was defined
to scale-up the process, and up to 65 mmol of substrates were efficiently
converted with a productivity of 0.3 mmol/min.
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