Advances in Green Organic Sonochemistry

Abstract

Over the past 15 years, sustainable chemistry has emerged as a new paradigm in the development of chemistry. In the field of organic synthesis, green chemistry rhymes with relevant choice of starting materials, atom economy, methodologies that minimize the number of chemical steps, appropriate use of benign solvents and reagents, efficient strategies for product isolation and purification and energy minimization. In that context, unconventional methods, and especially ultrasound, can be a fine addition towards achieving these green requirements. Undoubtedly, sonochemistry is considered as being one of the most promising green chemical methods (Cravotto et al. Catal Commun 63: 2-9, 2015). This review is devoted to the most striking results obtained in green organic sonochemistry between 2006 and 2016. Furthermore, among catalytic transformations, oxidation reactions are the most polluting reactions in the chemical industry; thus, we have focused a part of our review on the very promising catalytic activity of ultrasound for oxidative purposes.

CHAPTER 8. Sustainable Activation of Chemical Substrates Under Sonochemical Conditions

“…As presented previously, lab scale experiments in organic chemistry are very promising to create green processes in industry 23,89 . However, to our knowledge, no industrial scale sonoreactor was successfully employed for organic synthesis.…”

Ultrasound for Drug Synthesis: A Green Approach

“…In this context, several solutions are available, such as the reduction of the use of solvents [13]; the use of benign solvents like water; the use of negligible vapor pressure solvents, such as ionic liquids at room temperature; the use of bio-based solvents; or not using any solvent at all [14,15].…”

“…In addition, through its unique physico-chemical properties, water is able to increase the rates and selectivities of various chemical reactions via hydrophobic effects [17,18]. In addition, water favors cavitation, especially between 318 and 343 K, making this solvent ideal for sonochemistry [15,19]. Thus, a common use of ultrasonic irradiation and aqueous media should be a smart combination for the development of environmentally sustainable protocols.…”

Visualization of the Mechanical Wave Effect on Liquid Microphases and Its Application for the Tuning of Dissipative Soft Microreactors

“…Among all the types of stimuli, mechanical waves, namely sound/ultrasound, stand out due to the fact that they cannot directly work at a molecular level, but instead are able to interact with the media at microscopic level, initiating uncommon chemical transformations. One of the remarkable features of the ultrasound-assisted reactions is the possibility to achieve extreme conditions within the reaction mixture as a result of acoustic cavitation: formation and collapsing of vacuum bubbles inside the liquid media under sonication conditions, leading to the local emission of huge amounts of energy. − The use of sound energy has found a number of applications in organic synthesis, − preparation of nanomaterials, − processing of crude biomass, − and other processes. Along with the cavitation-based approaches, the mechanical standing wave techniques are widely used, for example, in the oil processing, food technology, and biotechnology. − To establish which particular sound wave effect is essential for achieving the desired structural changes in the chemical system, mechanistic insight into such challenging systems is needed, and fundamental studies of the mechanical wave-induced phenomena should be carried out.…”