- Glossary
- Practice Exercises
bromo - the prefix used in the name of a halogenoalkane to indicate it contains at least one bromine atom.
chloro β the prefix used in the name of a halogenoalkane to indicate it contains at least one chlorine atom.
chlorofluorocarbon - a type of halogenoalkane containing chlorine and fluorine atoms.
chlorofluoroalkanes have been responsible for damaging the Earthβs ozone layer, but alternative inert compounds, such as fluoroalkanes, are now replacing the use of CFCs.
electrophile β a species that takes part in a reaction by accepting a lone pair of electrons from a nucleophile.
electrophilic addition β a reaction in which an electrophile attacks a double bond and becomes bonded to one of the atoms that formed the double bond by a single covalent bond. One example is the formation of halogenoalkanes from alkenes, in which a halide ion attacks a carbonβcarbon double bond.
elimination β a reaction in which atoms are lost from a molecule but not replaced by others. One example is the reaction between a halogenoalkane and a base, forming an alkene, a halide ion, and water.
fluoro β the prefix used in the name of a halogenoalkane to indicate it contains at least one fluorine atom.
free radical β a highly reactive atom or group of atoms containing one or more unpaired electrons. One example is a chloride ion.
free radical substitution - a reaction in which a free radical attack an atom or group of atoms with a partial positive charge (an electrophile), substituting an existing atom or group of atoms called the leaving group. One example is the formation of halogenoalkanes from alkanes, in which a halogen atom substitutes a hydrogen atom bonded to a carbon atom.
halogenoalkanes β a group of organic molecules that are similar to alkanes but in which one or more hydrogen atoms are replaced by one or more halogen atoms. Also known as haloalkanes.
homolytic fission β the process in which a covalent bond is broken and one electron from the bond goes to each atom that formed the bond.
hydrolysis β the nucleophilic substitution of a halogenoalkane with a hydroxide ion.
initiation β the first step of a free radical substitution reaction, in which a free radical is formed by homolytic fission.
iodo β the prefix used in the name of a halogenoalkane to indicate it contains at least one iodine atom.
nucleophilic substitution β a reaction in which a nucleophile attacks an atom or group of atoms with a partial positive charge (an electrophile),substituting an existing atom or group of atoms called the leaving group. One example is the reaction of a halogenoalkane and ammonia, resulting in an amine and ammonium halide.
nucleophilic substitution β R-X + 2NH3 β R-NH2 + NH4X
nucleophilic substitution β R-X + OH- β R-OH + X-
nucleophile β an ion or molecule that donates a lone pair of electrons to form a covalent bond. Nucleophiles are attracted to atoms with a slight positive charge, such as those involved in a polar bonds.
primary halogenoalkane β the halogen atom is bonded to a carbon atom, which is itself bonded to one other carbon atom and two hydrogen atoms.
propagation β one or more steps in a free radical substitution reaction that follow initiation, in which new free radicals are created to continue the reaction.
R group β a symbol (R) used to represent an unspecified side chain or carbon chain in an organic molecule.
SN 2 mechanism of reaction is characteristic of primary haloalkanes.
SN 1 mechanism of reaction is characteristic of tertiary haloalkanes.
SN 1 mechanism and the SN 2 mechanism are both likely to play a part in the nucleophilic substitution of secondary.
substitution - a reaction in which an atom in a molecule is replaced by another atom or group of atoms.
termination - one or more steps in a free-radical substitution reaction that follow propagation, in which one free radical combine with another, leading to the end of the reaction.
tertiary halogenoalkane - the carbon atom bonded to the halogen atom is also bonded to three other carbon atoms (alkyl groups).
tertiary carbocations are more stable than primary carbocations due to the inductive effect of the alkyl groups attached to the carbon atom bonded to the halogen.