 Chemical reactions often need a solvent in order for them to take place. Can you remember what a solvent does? Pause the video and continue when ready. The answer is that a solvent will dissolve a solute. This means that two or more soluble compounds may then react with one another to form a new product. The issues are that a lot of chemical processes involve organic solvents. That is those containing carbon and hydrogen and sometimes halogen groups. Organic solvents are usually obtained from the fractional distillation of crude oil. This is an environmentally unfriendly process which uses a lot of energy and produces greenhouse gases. Also the solvents themselves are usually environmentally unfriendly and need to be disposed of carefully. Chemists around the world are looking towards green chemistry and the development of safer solvents. It may sound surprising but these safer solvents include special forms of water and carbon dioxide which exist in a supercritical state. Essentially this means that at a certain temperature these solvents will exist as a solid, liquid and gas simultaneously. You may be wondering why this is important. The reason is that non-polar compounds traditionally needing organic solvents can be dissolved in a safer solvent. More importantly, carbon dioxide and water are not flammable like most organic solvents and are very easy to obtain from other chemical processes. Imagine, instead of releasing carbon dioxide into the air and it contributing to global warming, we can collect it and use it as a solvent instead. This has been especially useful to the dry cleaning and textiles industries.