It once was a popular solvent in organic chemistry, but because of its adverse health effects, it is rarely used today. It is sometimes useful as a solvent for infrared spectroscopy, because there are no significant absorption bands above 1600 cm. Because carbon tetrachloride does not have any hydrogen atoms, it was historically used in proton NMR spectroscopy. In addition to being toxic, its dissolving power is low. Its use in NMR spectroscopy has been largely superseded by deuterated solvents (mainly deuterochloroform). The use of carbon tetrachloride in the determination of oil has been replaced by various other solvents, such as tetrachloroethylene. Because it has no C–H bonds, carbon tetrachloride does not easily undergo free-radical reactions. It is a useful solvent for halogenations either by the elemental halogen or by a halogenation reagent such as N-bromosuccinimide (these conditions are known as Wohl–Ziegler bromination).