Unit 2: Section 4: More Organic Chemistry

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A2 Chemistry
Michelle Browne
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Michelle Browne
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Pregunta Respuesta
What is the type of mechanism and conditions for alkane → haloalkane? -Free-radical substitution -UV light
What are the 3 stages to free-radical substitution? 1. Initiation 2. Propagation 3. Termination
What happens during initiation? -Free radicals are produced. Cl₂ → 2Cl●
What happens during propagation? -Free radicals are used up and created in a chain reaction. Cl● +CH₄ → ●CH₃ +HCl ●CH₃ +Cl₂ → CH₃Cl + Cl●
What happens during termination? -Free radicals are mopped up. Cl● + Cl● → Cl₂ ●CH₃ + ●CH₃ → C₂H₆ ●CH₃ + Cl● → CH₃Cl
What are CFCs? Chlorofluorocarbons
What are chloroalkanes and chlorofluroalkanes used as? Solvents
How is the ozone layer formed? O₂ + hv (UV radiation) → O● + O● O₂ + O● → O₃
How are chlorine free radicals formed? When the C-Cl bonds in CFCs are broken down by ultraviolet radiation.
How do the chlorine free radicals attack the ozone layer? Cl● + O₃ → O₂ + ClO● ClO● + O₃ → 2O₂ + Cl● Overall: 2O₃ → 3O₂
What is an alternative to CFCs? HFCs (hydrofluorocarbons)
What is the type of mechanism and conditions for haloalkane → alcohol? -Nucleophillic substitution -Warm aqueous sodium hydroxide
What is the type of mechanism and conditions for haloalkane → amine? -Nucleophilic substitution -Ethanol -Excess ammonia
What is the type of mechanism and conditions for haloalkane → nitrile? -Nucleophilic substitution -Alcoholic potassium cyanide -Reflux
What is the type of mechanism and conditions for haloalkane → alkene? -Elimination -Ethanol -Reflux
What does the OH(-) act as in different conditions? Aqueous conditions: nucleophile Anhydrous conditions: base
What is the test for double bonds? -Bromine water -Turns colourless if double bonds are present.
What is the type of mechanism and conditions for alkene → dibromoalkane? -Electrophilic addition -Br₂
What is the type of mechanism and conditions for alkene → haloalkane? -Electrophilic addition -HBr
What conditions are required for the hydration of alkene → alcohol? -Steam -300°C -60 atm -Phosphoric acid catalyst
What are the advantages of hydration of ethene? -Very fast -Pure product -Low labour costs
What are the disadvantages of hydration of ethene? -Ethene is from oil, a finite resource -Continuous process so requires expensive equipment
What are the advantages of fermentation? -Uses sugars, a renewable resource -Cheap equipment needed
What are the disadvantages of fermentation? -Very slow -Very impure so requires further processing -High labour costs
What conditions are needed for the dehydration of alcohol → alkene? -Reflux -Ethanol -Conc. sulfuric acid
What is the test for 1°, 2° and 3° alcohols? -Acidified potassium dichromate 1°- orange to green 2°- orange to green 3°- nvc
Which test is used for aldehydes and ketones? -Tollen's reagent Aldehyde: silver mirror Ketone: NVC
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