Organic - 3.3 Halogenoalkanes Flashcards
What are 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 refrigerant and solvent.
Define electrophile
Electron pair acceptor in an organic mechanism. Attracted to areas with a lot of electron/high negative charge.
Define elimination
Reaction in which molecule loses atoms or groups of atoms to form a C=C bond
Define free radicals
The species with an unpaired electron. Represented in mechanisms by a single dot.
What is 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.
Define nucleophile
An atom or molecule that donates an electron to form a covalent bond. Attracted to electron deficient areas.
Define nucleophilic substitution
The reaction of an electron pair donor (nucleophile) with an electronic acceptor (electrophile). Involves one species being replaced another species.
Define ozone
Ozone is formed naturally in the atmosphere. It is beneficial because it absorbs ultraviolet radiation and this prevents harmful radiation reaching the earth.
What is ozone depletion?
Chlorine atoms catalyse the decomposition of ozone and contributes the hole in the ozone layer
Define 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 is slightly negatively charged. Halogenoalkanes contain polar bonds due to the difference in electronegativity between halogen atom and carbon atom
Why is the C-X bond polar?
The halogen atom is more electronegative than the C atom.
What is the boiling point of halogenoalkanes?
Boiling point increases as chain length increases due to an increase in VDW forces.
Are halogenoalkanes soluble?
- Insoluble or only very slightly soluble in water.
- Soluble in organic solvents
How are chloroalkanes formed?
Chlorine will react with methane to form chloroalkanes and HCl gas.
What is ozone?
O3
Reacts with chlorine free radicals to form oxygen.
