Haloalkanes
Haloalkanes (alkyl halides) are compounds in which one or more hydrogens of a saturated hydrocarbon are replaced by halogen. The table below shows that several polyhaloalkanes are used commercially in various applications.
Recently some commercial uses of haloalkanes have been curtailed due to their carcinogenicity (CCl4) and the role that they have been postulated to play in destruction of the ozone layer.
Despite these negative factors, haloalkanes are often used as intermediate compounds in multistep syntheses of organic compounds. This module focuses on
The mode of preparation and/or reactivity of a haloalkane may depend on the degree of substitution (number of carbons) at the carbon bearing halogen. Thus it is useful to classify haloalkanes as shown.
In general, organic chemists classify to make it easier to get the “big picture“ and apply known results to predicting the outcome of reaction of a new compound with the same type of functional group and halides are classified as shown at the right.
Note that the classification is similar to alcohols.
ClCH2CH2Cl and CH2Cl2 solvents |
CClF3 Freon - refrigerant |
F3C–CHBrCl halothane - anaesthetic |
(–CF2CF2–)n Teflon nonstick polymer |
Recently some commercial uses of haloalkanes have been curtailed due to their carcinogenicity (CCl4) and the role that they have been postulated to play in destruction of the ozone layer.
Despite these negative factors, haloalkanes are often used as intermediate compounds in multistep syntheses of organic compounds. This module focuses on
- preparation of haloalkanes
- reactions of haloalkanes
The mode of preparation and/or reactivity of a haloalkane may depend on the degree of substitution (number of carbons) at the carbon bearing halogen. Thus it is useful to classify haloalkanes as shown.
In general, organic chemists classify to make it easier to get the “big picture“ and apply known results to predicting the outcome of reaction of a new compound with the same type of functional group and halides are classified as shown at the right.
Note that the classification is similar to alcohols.
| primary | one carbon bonded to C bearing halogen | CH3CH2Br |
| secondary | two carbons bonded to C bearing halogen |  |
| tertiary | three carbons bonded to C bearing halogen |  |