## 2 Topical Research Areas Related to Ionic Liquids and the Contribution of Spiroammonium Compounds
### Green Chemistry and the IL Concepts  
#### 2.2.1 The State of the Art  
One of the seventeen UN Sustainable Development Goals states the need for global protection of the world for the development and prosperity of people (Goal 12), referring to responsible consumption and production and reducing waste generation through prevention, reduction, recycling, and reuse [16]. This goal essentially includes the concept of \"green chemistry\", put forward in 1998. This concept is defined as the use of chemistry to prevent pollution through the application of an appropriate set of products and processes which reduce and, if possible, eliminate the use and formation of hazardous substances [17]. The ACS Green Chemistry Institute (GCI) has been in operation since 2000 within the Office of Sustainability and is part of the Division of Scientific Advancement at the American Chemical Society. The purpose of ACS GCI is to promote and enable the implementation of environmentally friendly and sustainable technologies, chemistry, and engineering on a global scale in chemical plants and society to preserve human health and ecosystems [18]. However, in the United States, the Toxic Substances Control Act of 1976 (TSCA) is a framework law outlining a comprehensive system for controlling toxic substances. It gives the Environmental Protection Agency the authority to regulate the production, processing, distribution, use, and disposal of existing and new chemicals to avoid unreasonable risks to health or the environment and to delay or prohibit production or marketing [19]. Green chemistry is a philosophy of chemical practice with a hazard reduction approach in mind. It can be applied to all aspects of chemistry: raw materials, solvents, processes, products, waste, etc. The resurgence of interest in ILs coincides with the greater awareness of GC [20]. The 12 principles of green chemistry relate to reducing the toxicity of the substances used in synthesis, the formation of the safest possible products and eliminating the generation of waste, atom economy with the participation of all components taken into the processes, the use of energy-efficient processes, catalysts, immediate control of the process with timely prevention of danger in the form of a fire, explosion, etc., as well as the reduction or elimination of auxiliary components of reactions. New technologies may be adopted if real benefits can be demonstrated. However, the effectiveness of the process must be assessed not only based on the final product but also on the cost in terms of environmental impact and waste toxicity [21]. The chemical industry plays a key role in society through innovative development and the creation of products with numerous beneficial properties. However, at the same time, the toxic and hazardous properties of many solvents, particularly chlorinated hydrocarbons, create a huge threat to the environment in the form of emissions and wastewater pollution. One of the twelve principles of green chemistry is that the use of auxiliary substances, such as solvents, protecting groups, and release agents, should be unnecessary and, if used, should be harmless [22]. It has been recognized that the use of non-traditional solvents, such as ILs, as alternatives to environmentally harmful traditional solvents can reduce the production of waste solvents and, therefore, significantly reduce the negative impact on the environment [23]. The first definition of ionic liquids was as materials composed entirely of ions with melting points, somewhat arbitrarily, below 100 \({}^{\circ}\)C [24; 25]. The distinctive features of ILs are their immeasurably low vapor pressure and non-flammability. These properties are environmentally friendly for human life. For this reason, they are called green solvents in contrast to traditional volatile and flammable organic solvents [23].