Organic

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  • Created on: 15-05-14 19:00
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Organic chemistry
Introduction
- Functional group: group of atoms which gives an organic compound its characteristic
properties and reactions
Benzene
- General formula: expresses ratio between atoms in a homologous series
ring
- Homologous series: group of compounds with the same general formula, trend in
chemical and physical properties
Naming and drawing
- Find longest chain
- Use smallest numbers possible when numbering
branches
Structural and skeletal formulae of butan-2-ol
- Arrange different groups alphabetically
- Use the prefixes di, tri, and tetra when there
is more than one of the same group
Hazard and risk
- Chemicals can be carcinogenic, flammable, or
harmful to the environment so risk assessments
are needed
- Risk can be reduced by:
- Working on a smaller scale
- Taking precautions (lab goggles, tongs when
heating, gloves when handling carcinogens,
not heating whilst adding reactive chemicals)
- Carrying out reaction using less hazardous
substances (not using rubidium instead of
sodium)
Alkanes
- General formula CnH2n+2
- Saturated hydrocarbons (Contain C and H only) with single bonds only
- Structural isomers (same molecular formula, different structural formula) exist as it is possible to join
atoms together in different ways
- Chain isomers: have different chains of C atoms (e.g. Butane and 2-methylpropane)
- Position isomers: have different positions of same functional group (e.g. Propan-1-ol and
propan-2-ol)
- Functional group isomers: have different functional groups (e.g. Propan-1-ol and
methoxymethane (an ether))
- Used as fuels
Alternative fuels
- Concentration of greenhouse gases in the air is rising, mostly from burning of fossil fuels
- Fossil fuels are burnt in power stations, aviation, industries, homes and vehicles
- CO produced enhances greenhouse effect global warming
- To reduce CO emissions alternative fuels are needed (e.g. Biofuels like biodiesel)
- Biofuels are carbon neutral as they come from plants (e.g. Vegetable oils) which originally took in
the CO to photosynthesise, so no net change in CO in air
- The above doesnt take into account fossil fuels burnt whilst planting, harvesting and processing
crops/making fertilisers

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Bioethanol is the main biofuel and is made by fermenting carbohydrates in crops like sugarcane,
converting glucose to ethanol and CO with a catalyst
- Biodiesel is used by extracting and processing oils from crops like rapeseed
Fractional distillation
- Necessary as crude oil contains too many long hydrocarbons and not enough short ones
- Furnace heats crude oil to around 400ºC
- Fractionating column is hotter at bottom and cooler at top
- Shorter hydrocarbons have lower boiling points so rise to top as…read more

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Chemical reactions of the alkanes
Combustion
- Form CO and HO when they react with oxygen
- Incomplete combustion forms soot (carbon) and CO as well as CO and HO
- Involves free-radical mechanism which occurs rapidly only when alkane is vaporised (hence why
less volatile alkanes burn less easily)
- Used to generate energy
Halogenation (free radical substitution)
- Initiation (with UV light): Cl2 2Cl (can also be shown with curly half-arrow with Cl - Cl Cl2)
- Propagation (reactions which keep chain going):…read more

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Reactions of the alkenes
- Addition of hydrogen (catalytic hydrogenation)
- With nickel catalyst at 150ºC
- Solid catalyst can be held in reaction vessel as products flow in and reactants flow out, so is
very convenient
- Used to be used in manufacture of butter-free spreads as vegetable oil is broken down into
unsaturated fats and then mixed with untreated oil so that there are no trans fats (these can
cause heart disease, as can saturated fats)
- Produces alkane
- Addition of halogens…read more

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Addition of hydrogen halides to unsymmetrical alkenes
-This is because the carbocation formed with its
positive charge in the middle of the carbon
chain is more stable than the one with its
charge at the end of the chain, as the more
stable one has two alkyl groups pushing
electrons towards the positively charged central
carbon
-This is an example of the inductive effect (= the
way in which electrons are either pushed
towards or pulled away from a carbon atom by
the atoms to…read more

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