There is not enough space in an overview of this length to do justice to this
important topic, covered at length elsewhere, but the following bullet points highlight some the key features of ionic liquids (as a class of materials—not all ionic liquids possess all of these properties, but all the properties are exhibited by some ionic liquids):
• Excellent solvents for organic, inorganic, and polymeric materials
• Acidic compositions are superacids (pKa « — 20)
• Some are very water sensitive and must be used in a dry box; others are hydrophobic and air stable
• Thermally stable under conditions up to 200°C
• No measurable vapor pressure at room temperature
• Nonflammable (but some are explosive!)
• Exhibit Br0nsted, Lewis, Franklin, and "super" acidity
• Highly solvating—therefore low volumes used, thus process intensification
• Catalysts as well as solvents
• Highly selective reactions
• New chemistry
However, and this must be clearly and unambiguously stated, as it is frequently misquoted, ionic liquids are not intrinsically green—we could design noxious ionic liquids with the greatest ease (such as, for example, ionic liquids containing alkaloid-based cations and cyanide as the anion). We frequently ask students (and indeed faculty) why they consider their work to be green, and all too often receive the answer: "Because I am using ionic liquids" (usually delivered to us as though we must be mentally retarded not to realize this!). This is quite simply wrong, and shows ignorance of the whole field. Nevertheless, ionic liquids can be designed to be green, and important work on the toxicity of ionic liquids is continuing both at the University of Bremen65 and the University of Notre Dame.66 In addition, the nonflammability of ionic liquids adds an invaluable safety bonus; solvents that will not burn are intrinsically safer to use industrially than flammable solvents. This should make a very interesting case study under the U.S. Green Chemistry Research and Development Act of 2005, S.1270,67 which (to the best of our knowledge) is the first time the principles of green chemistry have been enshrined in law. John Marburger [Office of Science and Technology Policy (OSTP)] has made a strong case for using green chemical approaches as a creative response to terrorism,68 and the use of ionic liquids in industrial processes will make them intrinsically safer than equivalent processes using conventional solvents, as many ionic liquids do not burn.
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Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.