Halogenoalkanes Flashcards
Chlorofluorocarbons
Chlorofluorocarbons, also known as CFCs, are chemicals containing carbon, chlorine and fluorine atoms. CFCs contribute to ozone depletion so they are banned for use in refrigerants and solvents
Electrophile
Electron pair acceptor in an organic mechanism. Attracted to areas with a lot of electrons/high negative charge
Elimination
A reaction in which a molecule loses atoms or groups of atoms to form a C=C bond
Free radicals
A species with an unpaired electron. Represented in mechanisms by a single dot
Free radical substitution
A photochemical reaction between halogens and alkanes to form halogenoalkanes. The reaction requires UV light and involves three stages: initiation, propagation and termination.
- Initiation initially creates a radical species.
- Propagation involves a series of chain reactions where free radicals bond to molecules to form new free radicals.
- Termination involves the reaction of free radicals with other free radicals to form new molecules
Nucleophile
An atom of molecule that donates an electron pair to form a covalent bond. Attracted to electron-deficient areas
Nucleophilic substitution
The reaction of an electron pair donor (the nucleophile) with an electron pair acceptor (the electrophile). Involves one species being replaced with another species
Ozone
Ozone is formed naturally in the upper atmosphere. It is beneficial because it absorbs ultraviolet radiation and this prevents harmful radiation reaching the earth. Ozone is formed by the following reaction:
3O2 (+UV light) —> 2O3
Ozone depletion
Chlorine atoms catalyse the decomposition of ozone and contribute to the hole in the ozone layer
Polar bond
A covalent bond where the electrons are not distributed equally. This causes the molecule to have a slight dipole so that one end is slightly positively charged and the other end slightly negatively charged. Halogenoalkanes contain polar bonds due to the difference in electronegativity between the halogen atom and carbon atom
