Halothane, fluorinated inhalation anesthetic

The above reaction is of particular interest because the product Y is the well-known inhalation anesthetic Halothane that replaced ether and other flammable and therefore dangerous anesthetics in the late 1950s. Nowadays, Halothane is, at least in the United States, replaced by even better fluorinated inhalation anesthetics. 

Halofluorocarbons and highly fluorinated ethers have been used as inhalation anesthetics for many years [91], The first anesthetic of this type was Halothane which was introduced clinically in 1956 [92], An excellent anesthetic with few unwanted side-effects, Halothane has the particular advantages of high chemical stability and non-flammability. Several alternative heavily fluorinated inhalation anesthetics have subsequently been introduced [93] (Scheme 4.42). 

Modem inhalation anesthetics are fluorinated to reduce the flammabihty. They were initially considered to be biochemically inert substances. However, with time came the recognition that not only are inhaled anesthetics metabolized in vivo [27] but also that their metabolites are responsible for both acute and chronic toxicities [28, 29]. Information gained from research over the past 30 years has led to changes in anesthesia practice, discontinuing the use of some anesthetics, for example methoxyflurane, due to its nephrotoxicity and more selective use of others, i.e. halothane, due to its rare liver toxicity. It has also provided the impetus for the development of new agents, isoflurane and desflurane, with properties that lower their toxic potential. The result has been improved safety but room remains for further improvement as our insight into toxicological mechanisms expands. 

Several of the agents used as general anesthetics are chiral and used as the racemate. This group includes parentally administered agents such as thiopental and ketamine, and a number of fluorinated agents administered by inhalation, including halothane, enflurane, isoflurane, and desflurane. 

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