hydrocarbons

• Alkanes are hydrocarbons that can be produced by the addition reaction of hydrogen to an alkene or by cracking of longer alkane chains.
• Alkanes are used in the production of alkenes and alkynes.
• Alkanes undergo combustion reactions.
• Alkanes are used in the production of lubricants.
• Alkanes are used in the production of detergents.
• Alkanes are used in the production of plastics.
• Alkanes are used in the production of cosmetics.
• Alkanes are used in the production of pharmaceuticals.
• Alkanes are used in the production of explosives.
• Alkanes are used in the production of fireworks.
• Alkanes are used in the production of pesticides.
• Alkanes are used in the production of herbicides.
• Alkanes are used in the production of fertilizers.
• Alkanes are used in the production of food additives.
• Alkanes are used in the production of animal feed.
• Alkanes are used in the production of pet food.
• Crude oil is a mixture of hydrocarbons containing alkanes, cycloalkanes and arenes (compounds with a benzene ring).
• This alkyl free radical can attack another chlorine/bromine molecule to form the halogenoalkane and regenerate the chlorine/bromine free radical.
• If there is enough chlorine/bromine present, all the hydrogens in the alkane will eventually get substituted (eg, ethane will become C Cl /C Br).
• Free radicals are very reactive and will attack the unreactive alkanes.
• This reaction is not very suitable for preparing specific halogenoalkanes as a mixture of substitution products are formed.
• The final step in the substitution reaction to form a single unreactive molecule is the end point.
• Alkanes are used in the production of feedstock for biofuels.
• The mechanism for the initiation and termination steps of the free-radical substitution reaction uses half headed arrows to show the movement of one electron (double headed arrows show the movement of a pair of electrons).
• The crude oil is extracted from the earth in a drilling process and transported to an oil refinery.
• The propagation step in the free-radical substitution reaction refers to the progression (growing) of the substitution reaction in a chain type reaction.
• At the oil refinery, the crude oil is separated into useful fuels by fractional distillation.
• Fractional distillation is a separating technique in which the wide range of different hydrocarbons are separated into fractions based on their boiling points.
• The first step of the free-radical substitution reaction is the initiation step in which two free radicals are formed by sunlight.
• The free-radical substitution reaction gives a variety of products and not a pure halogenoalkane.
• The termination step in the substitution reaction is when the chain reaction terminates (stops) due to two free radicals reacting together and forming a single unreactive molecule.
• Multiple products are possible in the termination step of the free-radical substitution reaction.
• The second step of the free-radical substitution reaction is the propagation step in which the reaction grows in a chain type reaction.
• You could be asked to draw the mechanism for initiation and termination steps for free radical substitution.
• In the C-H bond breaks homolytically (each atom gets an electron from the covalent bond) an alkyl free radical is produced.
• Incomplete combustion often takes place inside a car engine due to a limited amount of oxygen present.
• The free-radical substitution reaction consists of three steps: initiation, propagation, and termination.
• Alkanes can undergo free-radical substitution in which a hydrogen atom gets substituted by a halogen (chlorine/bromine).
• When alkanes are burnt in excess (plenty of) oxygen, complete combustion will take place and all carbon and hydrogen will be oxidised to carbon dioxide and water respectively.
• Alkanes are combusted (burnt) on a large scale for their use as fuels.