46
3 Sonication in Neoteric Solvents. A Further Look …
DES can be considered as cousins of ILs as they share several remarkable properties such as negligible vapour pressure, non-flammability, good solubility with
organic and inorganic compounds, etc. Similarly to ILs, some of their intrinsic properties can also be finely tuned by changing the HBA/HBD ratio. Owing to this
dynamic H exchange, DES are generally hydrophilic moieties. This may be a brake
to their development notably in the field of separation and analysis but the R&D
community is just beginning to take hold of the subject, and progresses are soon
to be expected. In addition, they are said to be non-toxic, biodegradable and biocompatible. They have subsequently gained high interest in many different fields
including:
→ Organic synthetic chemistry,
→ Catalysis,
→ Material chemistry,
→ Gas absorption and segregation,
→ Nanotechnology,
→ Biomass valorization and
→ Extraction, segregation and separation processes.
Owing to their natural constitution, DES are adequate for foods, pharmaceuticals
and cosmetics industries and may replace efficiently conventional molecular solvents
as well as ILs where biocompatibility and non-toxicity are critical.
3.3 Why Coupling Ultrasound to Neoteric Solvents
The rapid global awareness of the scientific community of the need to preserve our
environment at the end of the twentieth century prompted it to renew ways of thinking
and doing synthetic chemistry. This pivotal period between the twentieth and twentyfirst centuries coincides with the emergence of several technologies, ‘physical’ ones
such as microwave or ultrasound and ‘chemical’ ones such as NS media. All were
investigated singly or conjointly in different areas of chemical sciences but all with the
unique aim of improving all that could be improved in a reaction process: time, yield,
selectivity, recycling, toxicity, etc. Developing new synthetic pathways that are not
only efficient but also by-product free with high yields while being eco-compatible
is pressing but necessary nowadays challenge for organic chemists. Apart from the
environmental considerations set out above, the combination of neoteric solvents and
ultrasonic irradiation is therefore expected either in a synergistic effect or where this
coupling may overcome severe technical hurdles or open new fields of investigation.
First literature examples of NS/US coupling were released out the same year (2001)
with the study of a Heck system in an IL/US system (Deshmukh et al. 2001) and the
enhanced dissolution of uranium oxides in SC CO 2 /US (Trofimov et al. 2001). Since
then, success never faded and the number of publications combining US and NS is
exponentially increasing in particular with ILs (Chatel and MacFarlane 2014; Khaw
et al. 2017).
3 Sonication in Neoteric Solvents. A Further Look …
DES can be considered as cousins of ILs as they share several remarkable properties such as negligible vapour pressure, non-flammability, good solubility with
organic and inorganic compounds, etc. Similarly to ILs, some of their intrinsic properties can also be finely tuned by changing the HBA/HBD ratio. Owing to this
dynamic H exchange, DES are generally hydrophilic moieties. This may be a brake
to their development notably in the field of separation and analysis but the R&D
community is just beginning to take hold of the subject, and progresses are soon
to be expected. In addition, they are said to be non-toxic, biodegradable and biocompatible. They have subsequently gained high interest in many different fields
including:
→ Organic synthetic chemistry,
→ Catalysis,
→ Material chemistry,
→ Gas absorption and segregation,
→ Nanotechnology,
→ Biomass valorization and
→ Extraction, segregation and separation processes.
Owing to their natural constitution, DES are adequate for foods, pharmaceuticals
and cosmetics industries and may replace efficiently conventional molecular solvents
as well as ILs where biocompatibility and non-toxicity are critical.
3.3 Why Coupling Ultrasound to Neoteric Solvents
The rapid global awareness of the scientific community of the need to preserve our
environment at the end of the twentieth century prompted it to renew ways of thinking
and doing synthetic chemistry. This pivotal period between the twentieth and twentyfirst centuries coincides with the emergence of several technologies, ‘physical’ ones
such as microwave or ultrasound and ‘chemical’ ones such as NS media. All were
investigated singly or conjointly in different areas of chemical sciences but all with the
unique aim of improving all that could be improved in a reaction process: time, yield,
selectivity, recycling, toxicity, etc. Developing new synthetic pathways that are not
only efficient but also by-product free with high yields while being eco-compatible
is pressing but necessary nowadays challenge for organic chemists. Apart from the
environmental considerations set out above, the combination of neoteric solvents and
ultrasonic irradiation is therefore expected either in a synergistic effect or where this
coupling may overcome severe technical hurdles or open new fields of investigation.
First literature examples of NS/US coupling were released out the same year (2001)
with the study of a Heck system in an IL/US system (Deshmukh et al. 2001) and the
enhanced dissolution of uranium oxides in SC CO 2 /US (Trofimov et al. 2001). Since
then, success never faded and the number of publications combining US and NS is
exponentially increasing in particular with ILs (Chatel and MacFarlane 2014; Khaw
et al. 2017).