4) Organic Chemistry P2 Flashcards
Alcohols
Homologous series of compounds
-all contain the functional group -OH bonded to a carbon chain
Methanol molecular, structural, displayed formula
CH4O
CH3OH
Draw displayed
Ethanol molecular, structural, displayed formula
C2H6O
CH3CH2OH
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Propan-1-ol molecular, structural, displayed formula
C3H8O
CH3CH2CH2OH
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Butan-1-ol molecular, structural, displayed formula
C4H10O
CH3CH2CH2CH2OH
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Naming alcohols
e.g. Butan-1-ol
But - 4 carbon chain
an - saturated
1 - functional group on carbon 1 at lowest possible number from any direction
ol - -OH functional group
Ways ethanol can undergo oxidation
-complete combustion
-microbial oxidation
-treatment with an oxidising agent (heating with potassium dichromate(VI) in dilute sulfuric acid to form ethanoic acid)
Oxidation of ethanol - combustion
Alcohols undergo combustion to form carbon dioxide and water
Oxidation of ethanol - microbial oxidation
Bacteria in the air use oxygen in the air to oxidise the ethanol in the wine:
ethanol + oxygen → ethanoic acid + water
Oxidation of ethanol - treatment with an oxidising agent
Alcohols undergo oxidation to produce carboxylic acids when treated with oxidising agents
-ethanol heated with acidified potassium dichromate (VI)
-oxidises to ethanoic acid
-potassium dichromate turns from orange to green
Production of ethanol
-hydration of ethene
-fermentation
Production of ethanol - Hydration of ethene
Addition reaction where water is added to the ethene without forming any other product
Conditions:
-temp: 300C
-pressure: 60-70 atm
-concentrated phosphoric acid catalyst
Production of ethanol - Fermentation
-yeast added to sugar/ starch, left in warm and anaerobic conditions
-enzymes in yeast convert sugar into carbon dioxide and ethanol
-optimum temp: 30C
C6H12O6 –> 2C2H5OH + 2CO2
Fermentation vs hydration of ethene - resources, type of process, rate, quality, conditions
F: use renewable resources
H: Non renewable (ethene in crude oil)
F: batch process - inefficient
H: continuous flow process - more efficient
F: Slow, several days for each batch
H: fast
F: impure ethanol, needs further processing
H: much purer ethanol
F: gentle temps, atm
H: high temp, pressure, require high input of energy
Carboxylic acids
Homologous series of compounds that contain the -COOH functional group (Carboxyl)
Vinegar
Aqueous solution of ethanoic acid (diluted in water)
Methanoic acid molecular, structural, displayed formula
CH2O2
HCOOH
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Ethanoic acid molecular, structural, displayed formula
C2H4O2
CH3COOH
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Propanoic acid molecular, structural, displayed formula
C3H6O2
CH3CH2COOH
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Butanoic acid molecular, structural, displayed formula
C4H8O2
CH3CH2CH2COOH
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Naming carboxylic acids
e.g. Butanoic acid
But - 4 carbon chain
an - saturated
oic acid - -COOH functional group
Acid properties of carboxylic acids
-considered weak acids (pH3-5)
-turn litmus paper red
-universal indicator orange or yellow
-react same as other acids
Carboxylic acids + metals
–> salt + hydrogen
e.g. magnesium + ethanoic acid –> magnesium ethanoate + hydrogen
Ethanoate ions
Form when the ethanoic acid loses a hydrogen, become negatively charged
CH3COOH –> CH3COO-
Carboxylic acids + metal carbonates
–> salt + water + carbon dioxide
-fizzing produced
-gas produced turn limewater cloudy
Esters
Homologous series of compounds that contain the -COO functional group
ethyl ethanoate - structural, displayed formula
CH₃COOCH₂CH₃
Draw displayed formula
Formation of esters
React an alcohol and carboxylic acid in warm conditions in the presence of a sulfuric acid catalyst
ethanol + ethanoic acid –> ethyl ethanoate
in presence of acid catalyst
Practical: prepare a sample of an ester such as ethyl ethanoate
- Take mixture of ethanol and ethanoic acid in test tube
- Add drops of concentrated sulfuric acid
- Place test tube in beaker of hot water for 15 minutes
- Empty test tube onto cold sodium carbonate solution
- Bubbling observed
- Thin layer of ester floating on the surface
Drawing esters
Draw alcohol and carboxylic acid side by side
-OH removed from carboxylic acid
-H removed from alcohol
O from alcohol bonds to C from acid to make ester bond
-always draw acid section and then alcohol section
-draw methanol + propanoic acid
-draw propanol + ethanoic acid
Naming esters
e.g. Butyl Propanoate
Butyl - 4 carbon alcohol
Prop - 3 carbon carboxylic acid
an - saturated
oate - -COO functional group
Splitting up esters
-condensation reaction to make esters can be reversed to return back to alcohol and carboxylic acid
-hydrolysis reaction - add water
Uses of esters
-small esters commonly used in solvents
-sweet, fruity smell -in perfumes, food flavourings
-volatile - evaporate easily
Condensation polymerisation
Alcohols and carboxylic acids combine to form ester bonds (-COO)
-two different monomers join in an alternate pattern
-each ester bond formed causes a small molecule of water to be removed
Monomers of condensation polymerisation
Diols contain two -OH functional groups
Dicarboxylic acids contain two -COOH functional groups
Process of condensation polymerisation
Diol loses H on both sides
Dicarboxylic acids lose OH on both sides
Can join in long chains
H + OH lost forms water molecules
Draw reaction of ethanedioic acid and ethanediol
-draw it
Biodegradable polyesters
Biopolyesters
-e.g. made from lactic acid
