Organic halide
An organic halide has a halogen atom (fluorine, chlorine, bromine, or iodine) bonded to a carbon in the chain. Unlike the other functions on this list, the halogen never becomes the name's suffix — it's always treated as a substituent (prefix), even when it's the only group present in the molecule.
General formula
Naming rule
Name = [fluoro/chloro/bromo/iodo]- + base hydrocarbon name, with the lowest possible locant (e.g., 1-chlorobutane, not 4-chlorobutane).
How to name it with IUPAC
Use this sequence to move from the structure to the systematic name:
- Choose the carbon chain and number it so the halogen gets the lowest locant.
- Use fluoro-, chloro-, bromo-, or iodo- as a prefix.
- CH₃CH₂CH₂Br = 1-bromopropane: bromo at C1.
Examples
| Name | Formula |
|---|---|
| Chloromethane | CH₃Cl |
| 1-bromopropane | C₃H₇Br |
| Dichloromethane | CH₂Cl₂ |
| Trichloromethane (chloroform) | CHCl₃ |
Visual examples
See how the functional group appears inside the chain. Compare the drawings with the formulas in the table to practice visual recognition.
Chemical reading
The C–halogen bond is polarized. The halogen can leave, enabling nucleophilic substitution or elimination to form a double bond.
Properties and applications
Halides are synthesis intermediates, solvents, and components of some refrigerants; toxicity and environmental impact vary widely.
- Halides are always prefixes: fluoro-, chloro-, bromo-, and iodo-. CH₃CH₂CH₂Br is 1-bromopropane.
- Compare polarity, chain size, and hydrogen bonding before predicting physical properties.