organic Flashcards
Catalytic converters
remove unburnt hydrocarbons, oxides of nitrogen and carbon monoxide from exhausts
Flue gas desulphurisation
removes SO2 using CaO or CaCO3
Free radical substitutions require what and have which 3 steps
UV light
Initiation, propagation, termination
Thermal cracking
produces a high percentage of alkenes and uses high pressures and high temperatures
Catalytic cracking
uses a zeolite catalyst, slight pressure and high temperature. Catalytic cracking produces aromatic hydrocarbons and motor fuels
Alternatives to CFCs
include HFCs and hydrocarbons
Depletion of ozone
Cl + O3 ClO* + O2
ClO + O3 2O2 + Cl*
*Overall: 2O3 3O2
*UV light breaks C-Cl bonds in CFCs
- Ozone formed
O2 O + O*
O2 + O O3
*O3 prevents a lot of UV radiation from the sun from reaching earth
*UV radiation causes sunburn and skin cancer
Elimination – hydroxide ions must be dissolved in ethanol
- Anhydrous conditions
- Hydroxide ions act as a base
- Accept a proton from the carbon atom
mechanism forming alkene from haloalkane
elimination reaction
what conditions for elimination
reflux
Reagent for nucleophile substitution reactions
Ethanolic potassium cyanide
Formation of alcohols through nucleophilic substitution reactions
warm aqueous potassium or sodium hydroxide
formation of amines needs
- Hydrolysis
- Reagent = excess ethanolic ammonia
- The amine group has a lone pair of electrons, acts as a nucleophile
uses of PVC
properties can be modified with a plasticiser
rigid PVC used for drain pipes, window frames
what is plasticised pvc used for
cable insulation, clothing and tiles
why are polymers unreactive
main carbon chain is non-polar and saturated
addition reactions with Br2
produces a dihalogenoalkane
Br2 molecule is polarised by double bond
double bond repels electrons in Br-Br bond
addition reactions with HBr
produces halogenoalkane
if the alkene is asymmetrical there are 2 possible products
cold concentrated sulfuric acid catalyst
produces alcohol
addition reactions with H2SO4
major produce is produces via the most stable carbocation intermediate
minor product is produced from the other carbocation intermediate
if asymmetrical there are 2 possible products
cold conc, sulfuric acid acts as a catalyst
produces an alcohol
bromine water used to test for unsaturation in hydrocarbons
orange bromine water decolourises when mixed with an alkene
fermentation of glucose producing ethanol temperature
30 - 40 celsius
what is yeast used for in fermentation of glucose to produce ethanol
enzyme
equation for fermentation of glucose produces ethanol
C6H12O6 –> 2C2H5OH + 2CO2
biofuel
ethanol made via fermentation
biofuels are carbon neutral
decision surrounding use of biofuels
land used for biofuels cant be used for crops
all car engines would need modifying to use different fuels
are biofuels carbon neutral
fossil fuels must be burnt to power machinery and provide transportation
how do you separate ethanol when fermenting glucose
fractional distillation
hydration of alkenes
produces alcohols
what is needed to produce alcohols from alkenes
acid catalyst = phosphoric acid catalyst
and steam
what is needed to produce alkenes from alcohols through elimination reactions
- concentrated sulfuric acid catalyst
- product requires distillation
- alkenes produced from a renewable resource — addition polymers can be produced without the need for crude oil
oxidation of alcohols agent
acidified potassium dichromate
what are primary alcohols oxidised to
aldehydes
- distillation apparatus required to obtain the aldehyde
- aldehydes oxidised to carboxylic acid
- reflux apparatus to obtain the carboxylic acid
what are secondary alcohols oxidised to
ketones
are tertiary alcohols easily oxidised
no
test for alkenes
orange bromine water decolourises in the presence of an alkene
test for aldehydes
tollens - silver mirror
fehlings - blue to red
test for alcohols
- add acidified dichromate
- tertiary alcohols wont react
- primary and secondary will react and solution will turn from orange to green. test new solution for an aldehyde to determine if primary or secondary. aldehyde present = primary
test for carboxylic acids
- add sodium carbonate
- if present, then solution will fizz due to CO2
- CO2 will turn limewater cloudy
high resolution mass spectrometry
- measures molecular and atomic masses
- allows you to distinguish between compounds which have the same Mr
infrared spectroscopy works how
different covalent bonds absorb infrared radiation at distinctive wave numbers
fingerprint region
500 - 1500
unique to each compound
infrared radiation absorption contributes to global warming
greenhouse gases absorb infrared radiation
radiation re-emitted back toward the earth
increase in concentration of greenhouse gases increases the temperature of the earth
what is a racemic mixture
contains exactly equal quantities of each enantiomer from an optically active compound
do racemic mixtures display optical activity and why
because the enantiomer cancel out each other’s rotation of light
how is racemic mixture formed
produced from reactions which involve planar bond
planar bond has equal chance of being attacked from above or below
what are optical isomers
mirror images, cannot be superimposed
what do optical isomers have
chiral carbon
what are enantiomers
optical isomers
same structural formular but different arrangement in space
rotate plane-polarised light
one enantiomer will rotate light in a clockwise direction, and one in an anticlockwise direction
do ketones easily undergo oxidation
no
nucleophilic addition with aldehydes and ketones
react with potassium cyanide
produces hydroxynitriles - produces a mixture of enantiomers if the aldehyde/ketone is asymmetrical
potassium cyanide
irritant
reacts with water to produce hydrogen cyanide
hydrogen cyanide is extremely toxic
aldehydes can be reduced to what
primary alcohols
ketones can be reduces to what
secondary alcohols
what is the reducing agent for aldehydes and ketones
NaBH4
what is the mechanism in reduction of aldehydes and ketones
nucleophilic addition
benzene bonding
- one pair of unpaired electrons per carbon
- forms a ring of delocalised electrons
- delocalised ring of electrons means benzene is very stable
- benzene more stable
- all C-C bonds same length
- length between C-C bonds in benzene is between the length of C-C and C=C bonds
what mechanism is in nitration
electrophilic substitution
aromatic compounds attract nucleophiles due to dense benzene ring
destroy stable benzene ring
what temperatures do mononitration occur
<55 celsius
what does nitration of aromatics produce
nitrobenzene
reagents for nitration of aromatics
concentrated nitric acid and sulfuric acid
produce the NO2+ electrophile
sulfuric acid acts as a catalyst
friedel crafts acylation
aromatics heated under reflux in a non-aqueous solvent
produces phenylketones
mechanism of friedel crafts acylation
electrophilic substitution
what catalyst for friedel crafts acylation
AlCl3
generates electrophile from the acyl chloride
which is used more in industry: ethanoic anhydride or enthanoyl chloride
ethanoic anhydride because it is cheaper and safer
nucleophilic addition-elimination
acid anhydride and water
produces carboxylic acid
nucleophilic addition-elimination
acid anhydride and amines
produces N-substituted amide
nucleophilic addition-elimination
acid anhydride and alcohol
produces an ester
nucleophilic addition-elimination
acid anhydride and ammonia
produces an amide
amide have functional group -CONH2
acyl chloride functional group
-COCl
carboxylic acids
weak acids
carboxylic acids react with alcohols
condensation reaction
esterification reaction
forms esters
strong acid catalyst required e.g. conc sulfuric acid
carboxylic acid react with carbonates
form co2
animal fats and vegetable oils are esters of what
propan-1,2,3-triol (glycerol)
fats and oils can produces soap and glycerol how
alkaline hydrolysis
naming esters
first part from alcohol, second from carboxylic acid
common uses of esters
flavourings
plasticisers
perfumes
solvents
functional group of esters
-COO-
what is biodiesel a mixture of
methyl esters of long chain carboxylic acids
how is biodiesel produced
reacting vegetable oils with methanol with a potassium hydroxide catalyst
formation of aromatic amines
- reduction of nitro aromatic compound
- react with tin metal and conc HCl followed by alkali
- obtains aromatic amine from salts
heating a halogenoalkane with ammonia
- formation of aliphatic amines
- nucleophilic substitution reaction
- produces mix of primary, secondary and tertiary amines and quaternary ammonium salts
- excess ammonia favours primary amine
reduction of a nitrile
- forms aliphatic amine
- react with LiAlH4 in a non-aq solvent followed by dilute acid
OR - react with hydrogen and a nickel catalyst
industrially: form aliphatic amine with hydrogen and nickel or with LiAlH4
hydrogen and nickel catalyst
more affordable
quaternary ammonium salts
- formed when nitrogen atom forms four covalent bonds
- forms positive ion
- used as cationic surfactants
- used in fabric cleaners and hair products
nucleophilic properties of amines
- lone pair of electrons on nitrogen atom
- nucleophilic sub with halogenoalkanes
- nucleophilic addition-elimination reactions of primary amines and ammonia with acyl chlorides and acid anhydrides
amines can form dative covalent bond
lone pair of electrons on nitrogen
dative covalent bond with H+ ion
base strength of amine depends on
availability of lone pair of electrons
- ammonia is a stronger base than aromatic amines
- on aromatic amines the N lone pair is delocalised so less available to accept proton
- primary aliphatic ammines are stronger bases than ammonia due to positive inductive effect pushing e- onto N, makes lone pair more available to accept proton
which are more rigid : condensation or addition polymers
condensation
permanent dipole dipole and hydrogen bonds
polar bonds
polymers in landfill
- cheap and easy
- methane released in decomposition
- large areas of land
- leaks contaminate water supplies
recycling polymers
- contamination of plastic can occur during recycling
- involved collecting, sorting, processing
- involves raw materials
- cheaper than making new plastics
incineration of polymers
toxic gases released - scrubbers must be used to remove HCl
heat produced can be used to generate electricity
are polymers biodegradable
condensation are
- broken by hydrolysis
- slow
addition polymers are chemically inert
- difficult to dispose of
- non-polar chains
cisplatin adverse effects
prevents healthy cells from reproducing therefore hair loss and suppresses immune system
cisplatin as anticancer drug
- binds to DNA and causes kinks in helix
- stops tumour cells replicating
- ligand replacement reaction
- a bond is formed between platinum and a nitrogen atom in guanine
13C NMR standard
tetramethylsilane (TMS)
what is NMR
different amounts of energy absorbed by nuclei in dif environments
used to determine structure of molecules
samples in H NMR dissolved in what
deuterated solvents or CCl4
what is used as standard in NMR and why
TMS (tetramethylsilane)
- produces a single peak away from other peaks
- inert and non toxic
- volatile and easy to remove
separation in chromatography depends on
distribution of substances in mobile and stationary phase
gas chromatography
- used to separate volatile liquids
stationary phase of gas chromatography
solid or solid coated in liquid
solid packed into a long coiled tube ration
mobile phase of gas chromatography
unreactive carrier gas
what is gas chromatography usually followed by
mass spectrometry
thin layer chromatography mobile phase
solvent
thin layer chromatography stationary phase
glass or metal plate coated in silica or alumina
column chromatography used for
separating solutions
more soluble chemical has a higher affinity for the solvent
therefore travels quicker through column
mobile phase of column chromatography
mixture allowed to drain down column along with mobile phase
stationary phase of column chromatography
stationary phase in a glass column packed with slurry of an absorbent material
TLC solvent moves up paper carrying substances in mixture
- more soluble chemical spends more time in solvent
- means it will move further up the plate
- UV light or locating agents
- reveals colourless chemicals on the plate
