“…4 The few promising green alternatives for polar aprotic solvents include γ-valerolactone (GVL), 5 Cyrene, 6 propylene carbonate (PC), 7 N-butylpyrrolidone (NBP) 8 and methyl 5-(dimethylamino)-2-methyl-5-oxopentanoate (1). 9 While some of these solvents are only available commercially on a gram scale, 1 is the main component of the solvent PolarClean, which is produced at the ton scale by Solvay. A toxicological study of 1 found low acute toxicity (no observed adverse effect at 1000 mg kg −1 day −1 rat) and no evidence of carcinogenity, genotoxicity or mutagenicity.…”