Solvents for sustainable chemical processes

Abstract

Worldwide, socioeconomic strategies encourage -and may soon enforceindustrial sustainability. Therefore, innovative research and approaches must provide short and long term solutions to reach future legislative targets. For chemical processes, the development of solvents that facilitate reaction and subsequent product separation is paramount to secure economic competitivity while minimizing impact on the environment and energy consumption. Tunable and switchable solvents were developed to address synergistically reaction and separation. Tunable solvents change properties continuously upon application of an external stimulus. For example, organic aqueous solvents allow for the reaction to be homogeneously catalyzed followed by a simple and efficient heterogeneous separation of the product (commonly a heterogeneous catalysis attribute). Chemical processes mediated by water at or below the near critical range can also alleviate the shortcomings of current synthetic strategies (waste production and management, remediation costs). In contrast, switchable solvents change physical properties abruptly upon application of an external stimulus. Piperylene sulfone is one example and can provide a recyclable alternative for dipolar, aprotic solvents such as dimethylsulfoxide (DMSO). Solvents can accomplish more than heat and mass transfer; they can actively contribute to facilitate reaction and product separation while minimizing waste generation and energy consumption.

Ionic Liquid Aggregation Mechanism for Nanoparticle Synthesis

“…Silylamine reversible ionic liquids (RevILs) are a relatively new class of ILs that were originally designed for CO 2 sequestration then later repurposed for nanoparticle synthesis. − Silylamine liquids possess a switchable duality capable of converting between the molecular and ionic forms upon reaction with CO 2 , according to Scheme . RevILs have properties similar to traditional ILs but also have the advantage of switchable moieties, meaning nanoparticles synthesized with RevILs can be easily stabilized and destabilized at will.…”

Green Synthesis of Metal and Metal Oxide Nanoparticles: A Review of the Principles and Biomedical Applications

“…Thus, inspired by the comprehensive merits of Sc-W and Sc-CO 2 solutions, many SCF-based approaches have been developed for nanomaterial synthesis [27,47]. As another example, supercritical water can also serve as a good solvent system for many reactions, as it has a critical temperature of 646 K and a pressure of 22.1 MPa [56].…”

Copper-Catalyzed Synthesis of Indoles and Related Heterocycles in Renewable Solvents

“…This atom-economical and copper-catalyzed methodology proceeded via a presumed three-step sequence(1) aldol condensation, (2) intramolecular C–N cross-coupling via an advantageous six-membered cupracycle (X = I or Br) in a Goldberg-type reaction, , and (3) deacylation (Scheme )to give the key heterocycles in good yields. Yet the reaction utilized dipolar aprotic solvents, media that negate any environmental benefit gained in reaction solubility by requiring large amounts of additional organic solvent and water to recover the product during workup. , Typically, dipolar aprotic media are also not easily substituted, a contemporary topic of discussion in green chemistry circles. − Herein, we report that the simple and efficient one-pot three-step transformation can be conducted in more benign solvents available from renewable resources.…”