organic chem Flashcards
homologous series and functional groups
alkanes
-CnH2n+2
alkenes
-carbon-carbon double bond
-CnH2n
alcohols
-hydroxyl OH
-CnH2n+1OH
carboxylic acids
-carboxyl COOH
CnH2n+1COOH
IUPAC naming
-longest carbon chain with principal functional group should be named as the stem
-number the chain starting from principal functional group/ such that the overall numbering of the substituents are the lowest numbers
-if there are multiple substituents to be named in the prefix, name the substituents in alphabetical order
-if there are more than 1 of the same substituent on the same carbon atom, ‘di-‘, ‘tri-‘ and ‘tetra-‘ are used
names of stem
1 meth-
2 eth-
3 prop-
4 but-
5 pent-
6 hex-
7 hept-
8 oct-
9 non-
10 dec-
name of substituents
-CH3 methyl
-C2H5 ethyl
-C3H7 propyl
-C4H9 butyl
-C5H11 pentyl
-F fluoro
-Cl chloro
-Br bromo
-I iodo
fractional distillation of petroleum/ crude oil
-lighter fractions with fewer number of carbon atoms have lower boiling points, collected at the top
-heavier fractions with greater number of carbon atoms have higher boiling points, collected at the bottom
uses of petroleum fractions
-petroleum gas collected at the top used for fuel for cooking and heating
-petrol used for fuel for car engines
-naphtha used for chemical feedstock for making petrochemicals like plastics and detergents
-kerosene used for fuel for aircraft engines
-diesel used for fuel for diesel engines
-lubricating oil used for lubricant machines, making waxes and polishes
-bitumen used for making road surfaces and roofing
uses and how to conserve petroleum
-90% used as fuel to generate heat and electricity, powers motor vehicles and industrial activities
-10% used as feedstock for manufacture of plastics, medicines, fertilisers, pesticides and synthetic rubber
to conserve petroleum
-reduce the use of petroleum
-use alternative energy sources such as biofuel, solar energy and nuclear energy
-design power stations and vehicles that use petroleum more efficiently
physical properties of alkanes
as Mr increases,
-melting and boiling points increases. stronger intermolecular forces between molecules as number of electrons increases.
-density increases
-viscosity increases
-flammability decreases
-insoluble in water, but soluble in organic solvents
chemical properties of alkanes
-complete combustion forms water vapour and carbon dioxide
-incomplete combustion forms water vapour, carbon dioxide, carbon and/ or carbon monoxide
substitution reaction
-reagents - generally Cl2(g) or Br2(g)
-conditions - uv light, provides activation energy
-observations - greenish-yellow Cl2 turns colourless or reddish-brown Br2 turns colourless
-HCl/ HBr(g) formed
physical properties of alkenes
as Mr increases,
-melting and boiling points increases. stronger intermolecular forces between molecules as number of electrons increases.
-density increases
-viscosity increases
-flammability decreases
-insoluble in water, but soluble in organic solvents
physical properties of alkanes vs alkenes
-melting and boiling point of alkenes is slightly lower than alkanes with the same number of carbon atoms
-each alkene has fewer electrons than corresponding alkane with the same number of carbon atoms, hence weaker intermolecular forces between molecules
catalytic cracking of long chain hydrocarbons
-reagents - long chain alkane
-conditions - high temperature, finely divided SiO2 or Al2O3 catalyst
purpose of catalytic cracking
-produce hydrogen for haber process and hydrogen fuel cell
-produce short chain alkenes as raw material for making alcohols like ethanol and plastics like poly(ethene)
-produce short chain alkanes that are generally higher in demand than longer chain alkanes
chemical properties of alkenes
-complete combustion forms water vapour and carbon dioxide
-incomplete combustion forms water vapour, carbon dioxide and carbon and/ or carbon monoxide
addition reactions
-saturated organic compounds are alkanes with single carbon-carbon bonds
-unsaturated organic compounds are alkenes with double or triple carbon-carbon bonds
addition of hydrogen
-reagents - hydrogen
-conditions - 200ºc, nickel catalyst
-used to convert unsaturated fats to saturated fats, eg. hydrogenation of vegetable oil to form margarine
addition of bromine
-reagents - Br2(l)
-conditions - in the dark to prevent substitution reaction from occurring
-observations - reddish brown bromine turns colourless
addition of steam
-reagents - steam
-conditions - 300ºc, 65 atm, H3PO4 catalyst
-produces alcohol
addition of hydrogen halides
-reagents - hydrogen halides, eg. HF, HCl, HBr, HI
-conditions - room temperature
addition polymerisation
-reactants - alkene monomer
-conditions - high temperature and pressure, presence of catalyst
physical properties of alcohols
as Mr increases,
-melting and boiling points increases. more energy required to overcome the stronger intermolecular forces of attraction between molecules as number of electrons increases.
-density increases
-viscosity increases
-flammability decreases
-solubility in water decreases
production of alcohols
addition of steam to alkenes
-reagents - steam
-conditions - high temperature and pressure (300ºc, 65 atm), H3PO4 catalyst
fermentation of glucose to produce ethanol
-equation - C6H12O6 —> 2C2H5OH + 2CO2
-reagents - C6H12O6
-conditions - room temperature (optimal temperature for yeast, above will be denatured), absence of oxygen (for anaerobic respiration, as aerobic respiration may lead to ethanol oxidising to ethanoic acid), yeast, water
-separate ethanol from mixture by fractional distillation
chemical properties of alcohols
-complete combustion forms water vapour and carbon dioxide
-incomplete combustion forms water vapour, carbon dioxide, carbon and carbon monoxide
oxidation with acidified KMnO4
-reagents - acidified potassium manganate (VII) solution
-conditions - heat under reflux
-observations - purple acidified potassium manganate (VII) solution turns colourless
-alcohol becomes a carboxylic acid
oxidation with oxygen and bacteria in air
-reagents - oxygen
-conditions - presence of bacteria
-alcoholic drinks turn sour when exposed to air and bacteria for some time due to formation of ethanoic acid
physical properties of carboxylic acids
-carboxylic acids are weak acids, have a sour taste, conduct electricity when dissolved in water due to mobile ions and turn moist blue litmus paper red
as Mr increases,
-melting and boiling points increases. more energy required to overcome the stronger intermolecular forces of attraction between molecules as number of electrons increases.
-density increases
-viscosity increases
-flammability decreases
-solubility in water decreases
production of carboxylic acids
oxidation of alcohols with acidified KMnO4
-reagents - acidified potassium manganate(VII) solution
-conditions - heat under reflux
-observations - purple acidified potassium manganate(VII) solution turns colourless
oxidation of alcohols with oxygen and bacteria in air
-reagents - oxygen
-conditions - presence of bacteria
chemical properties of carboxylic acids
-complete combustion forms water vapour and carbon dioxide
-incomplete combustion forms water vapour, carbon dioxide, carbon and carbon monoxide
-acid + base —> salt + water
-acid + reactive metal —> salt + hydrogen
-acid + carbonate —> salt + carbon dioxide + water
-ethanoic acid (ionises partially) —> ethanoate ion and hydrogen ion
condensation reaction/ esterification
-reagents - alcohol and carboxylic acid
-conditions - heat under reflux, concentrated H2SO4 (catalyst, acts as a dehydrating agent to remove water)
-remove H2O
-reverse reaction of esterification is hydrolysis (requires addition of H2O)
esters
-generally have a sweet smell
-used for artificial food flavouring, perfumes, cosmetics, etc.
-name the alcohol part first (H removed) then the acid part (OH removed), eg. methyl ethanoate
