Tools and techniques for solvent selection: green solvent selection guides

Abstract

Driven by legislation and evolving attitudes towards environmental issues, establishing green solvents for extractions, separations, formulations and reaction chemistry has become an increasingly important area of research. Several general purpose solvent selection guides have now been published with the aim to reduce use of the most hazardous solvents. This review serves the purpose of explaining the role of these guides, highlighting their similarities and differences. How they can be used most effectively to enhance the greenness of chemical processes, particularly in laboratory organic synthesis and the pharmaceutical industry, is addressed in detail.

Recycling of Sulfuric Acid in the Valorization of Biomass Residues

“…The other possibilities include esters like acetates, from which ethyl acetate a has low boiling point and low miscibility with water. Other organic solvents could have better properties as an extracting agent; however, in the present study our aim was to apply a solvent that can be generated from biomass basis [22,23].…”

C–H and N–H Bond Annulation of Benzamides with Isonitriles Catalyzed by Cobalt(III)

“…8 Within our program for C-H bond functionalization using first row transition metal catalysts, 6a,9-11 we wish to report the cobalt-catalyzed formal [4+1] annulation of benzamides and isonitriles using CPME as a 'green' solvent under mild conditions. 12,13 We began our investigation by screening various reaction parameters using the eco-friendly solvent cyclopentyl methyl ether (CPME) as the reaction medium, with benzamide 1a and tert-butyl isonitrile (2a) as model substrates; the results are summarized in Table 1. Iminoisoindolinone 3a was isolated in 80% yield, when cobalt(II) acetate was used as a catalyst precursor, along with sodium pivalate as the base and silver carbonate as the oxidant at 100 °C for 24 h (entry 1).…”

“…Changing CPME to another eco-friendly solvent, dimethyl carbonate, gave a lower yield (entry 10). Further lower the quantity of oxidant or base gave satisfactory results (entries [11][12][13]. Our control experiments reveal that the catalyst, base, oxidant, and quinoline for bidentate chelation were crucial for the reaction to proceed (entries [14][15][16][17][18].…”

“…7.97 (dd,J = 8.3,1.3 Hz,1 H),7.84 (dd,J = 7.1,1.3 Hz,1 H),1 H),7.42 (dd,J = 8.4,3.9 Hz, 1 H), 0.79 (s, 9 H). 13 C NMR (CDCl 3 , 101 MHz): δ = 168. 51, 151.14, 148.69, 145.23, 140.22, 136.17, 135.51, 134.67, 132.89, 132.85, 132.55, 131.67, 129.76, 129.13, 128.48, 127.03, 125.86, 123.57, 122.07, 55.66, 30.68.…”

“…8.13 (dd,J = 8.3,1.7 Hz,1 H),7.81 (dd,J = 7.7,1.8 Hz,1 H),2 H),7.35 (dd,J = 8.2,4.2 Hz,1 H),1 H),2.16 (d,J = 1.7 Hz,3 H), 1.26 (s, 9 H). 13 C NMR (CDCl 3 , 101 MHz): δ = 170. 38, 152.42, 150.12, 144.13, 141.44, 135.97, 132.42, 130.88, 129.04, 128.15, 125.82, 122.95, 121.15, 55.40, 32.18, 11.48 86, 151.92, 150.89, 145.77, 144.42, 136.02, 135.83, 132.07, 130.07, 129.44, 129.09, 129.02, 128.82, 127.87, 125.83, 122.00, 121.76, 55.45, 30.87 …”