Vapor-compression refrigeration replaced, such as sulfur dioxide. Haloalkanes are also an order(s) of magnitude more expensive than petroleum derived flammable alkanes of similar or better cooling performance. Unfortunately, chlorine- and fluorine-bearing refrigerants reach the upper atmosphere when they escape. In the stratosphere, CFCs break up due to UV radiation, releasing their chlorine free radicals. These chlorine free radicals act as catalysts in the breakdown of ozone through chain reactions. One CFC molecule can cause thousands of ozone molecules to break down. This causes severe damage to the ozone layer that shields the Earth's surface from the Sun's strong UV radiation, and has
S-Nitrosothiol exist for their synthesis. They can be synthesized from thiols using NaNO/H+, NO, NO, HNO, NOCl, RONO, NO, HNO, bovine aortic endothelial cells, among others. NaNO/H+ and "tert"-butyl nitrite (tBuONO) are commonly used. Once formed, these deeply colored compounds are often thermally unstable with respect to formation of the disulfide and nitric oxide: "S"-Nitrosothiols release NO upon treatment with acids: and they can transfer nitroso groups to other thiols: "S"-Nitrosothiols can be detected with UV-vis spectroscopy. S-Nitrosothiol "S"-Nitrosothiols, also known as thionitrites, are organic compounds or functional groups containing a nitroso group attached to the sulfur atom of a thiol.