6. organic chemistry I (as) Flashcards
no of carbon and stem name
1 meth
2 eth
3 prop
4 but
5 pent
6 hex
7 hept
8 oct
9 non
19 dec
alkanes suffix
ane
branched alkane
alkyl
alkenes
ene
halogen alkanes
chloro bromo iodo
alcohol
ol
aldehydes
al
ketones
one
cycloalkane
cyclo…ane
craboxylic acid
oic acid
different types of reactions
addition
polymerisation
elimination
substitution
hydrolysis
oxidation
reduction
addition reaction
joining two or more molecule to form a larger molecule
polymerisation reaction
joining together lots of simple molecules to form a giant molecule
elimination
small group of atoms break away from a larger molecule
substitution
one species is replaced by another
hydrolysis
splitting a molecule into two new molecules by adding h+ and oh - derived from water
oxidation
any reaction where species loses e
reduction
reaction which species gains e
mechanism
diagrams that break down a reaction into individual stages
curly arrows show
how electron pairs move around
some types of mechanisms addition
nucloephilic addition
electrophilic addition
radical addition
nucleophiles
electron pair donors
often negatively charged ion or a species that contain a lone e- pair
,, e- rich and attracted to places that are e- poor
electrophiles
e- pair acceptors
often positively charged ions
electron poor ,, attracted to places that are electron rich and like to react w negative ions or atoms w lone pairs
radicals
have unpaired e-
and very reactive
types of structural isomer
chain isomers
positional isomers
functional group isomers
chain isomers
isomers have similar chemical properties but physical properties like bp is different because change in shape of molecule
positional isomers
different physical properties and chem properties may be also different
functional group isomers
have diff physical and chemical properties
atoms cannot be arranges into diff functional groups
alkanes are… general formula, bonds
saturated hydrocarbons
cnh2n+2
four single bonds with other atoms
all carbons carbon are single bond
types of bond fission
homolytic
heterolytic
bond fission def
breaking a covalent bond
heterolytic fission
the bond breaks unevenly with one of the bonded atoms receiving both electros from bonded pair
two diff substances formed
homolytic fission
bond breaks evenly and each bonding atom receives one electron from bonded pair. two electrically uncharged radicals are formed
halogens react with alkanes to form
halogenoalkanes
photochemical reactions def
reactions that are started by light
example of photochemical reaction + type of light needed
halogens reacting with alkanes and ultraviolet light needed to get going
during halogens reacting with alkanes what happens and what type of reaction is this called
hydrogen atom is substituted by a halogen in a free radical substitution reaction
reaction mechanism has three stages
initiation
propagation
termination
initiation reaction what happens
radicals are produced
sunlight provides energy enough energy to break bond
bond split equally and each atom gets to keep one electron
photodissociation def
light is used to provide enough energy to break bonds
propagation
radicals are used up and created
radical attacks molecule
new radical another molecule
and the new radical formed attacks another molecule until all of molecule are wiped out
termination reaction
radicals are destroyed
radicals are mopped up by reacting together to from stable molecules
two free radicals join together and make a stable molecule
problem with radical substitution
you don’t only get the product you’re after but a mixture of products
other substitution reactions can take place
radical substitution can take place at any place along the carbon change ,, mixture of structural isomers formed
crude oil def
mixture of hydrocarbons
ways to separate crude oil
fractional distillation
fractional distillation steps
crude oil is vaporized (350degrees celsius)
vaporized crude oil goes into fractionating column
up the column it gets cooler
alkanes diff molecules have diff chain lengths ,, diff bps each condense at diff temp
fractions are drawn off at diff levels
cracking
breaking long chain alkanes to shorter hydrocarbons
breaks c-c bonds
types of cracking
thermal cracking
catalytic cracking
thermal cracking conditions and produces
high temp (1000)
high pressure ( 70 atm)
produces a lot of alkenes
catalytic cracking conditions and produces
uses zeolite catalyst
slight pressure
high temp (450)
produces automatic hydrocarbons and motor fuel
zeolite catalyst
hydrated aluminosilicate
uses of catalyst
cuts costs because reaction can be done at low pressure and lower temp and speeds up reaction saving time and money
aromatic compounds
contain benzene rings which contain 6 carbon atoms w delocalized rings of electrons
alkanes can be reformed into
cycloalkanes and aromatic hydrocarbons
knocking def
alkanes explode of their own accord when fuel or air mixture in the engine is compressed
which type of alkanes are most likely to cause knocking
straight chain alkanes
if you burn alkanes with oxygen what is produced and what type of reaction is this
carbon dioxide and water
combustion reaction
incomplete combustion of alkanes produces
carbon monoxide, carbon, water
combustion reactions are
exothermic
larger alkanes release
more energy per mole because they have more bonds to react
pollutants from burning fossil fuels include
carbon monoxide
unburnt hydrocarbons
carbon particulates
oxides of sulfur
oxides of nitrogen
carbon monoxide is
toxic
sulfur dioxide and oxides of nitrogen lead to
acid rain
carbon monoxide effects
binds to haemoglobin and ,, less oxygen carried in bloodstream ,, oxygen deprivation
sulfur dioxide effects
sulfur burns and produce sulfur dioxide gas which enter the atmosphere and dissolves in the moisture and converted into sulfuric acid
oxides of nitrogen effects
produced under high pressure and temp in car engines and then dissolve in moisture and converted to nitric acid and fall as acid rain
catalytic converters
remove pollutants from car emissions
how do catalytics converters work
get rid of pollutants using platinum catalyst to change them to harmless gases
main fossil fuels and why
coal, oil, and natural gas
easily extractable and release a large amount of energy when burnt
biofuels def
fuels made from living matter over a long time
types of biofuel
bioethanol- ethanol made by fermentation of sugar from crops
biodiesel- refining renewable fats and oils
biogas-breakdown of organic gas
biofuels how are they carbon neutral
produce co2 when burned but the plants absorbed the co2
one problem why switching from fossil fuels to biofuel in transport
and other problem
petrol car engines would need to be modified to use fuels with high ethanol concentrations
need land to grow food
alkenes are… general formula, bonds
unsaturated hydrocarbons
general formula cnh2n
at least one c-c double bond
sigma bond def and what it gives
direct overlap of s or p orbitals that lie directly between the nuclei of the 2 bonding atoms
gives the highest possible electron density between 2 positive nuclei
covalent bond def
a strong electrostatic force of attraction between between the two nuclei of two atoms and the bonding electrons of their electrons
diff types of bonds
pi bond
sigma bond
pi bond
sideways overlap of p orbitals above and below the nuclei of the 2 bonding atoms
strongest type of covalent bonds
sigma bond
what is the bond enthalpy of sigma bonds and why
high bond enthalpy
because high electron density between nuclei which means strong electrostatic force of attraction between nuclei and shared pair of electrons
bond enthalpy of pi bond and why
relativey low bond enthalpy
electron density spread out above the nuclei and causes electrostatic attraction between nuclei and bonding pair of electrons is weaker
what is the strength diff between double bond and single bond
double bond (pi bond and sigmas bond) is less than twice as strong as a single bond (sigma bond)
carbon carbon double bond …. rotate and why
can’t because they all lie on same plane (planar)
sterioisomers def and when they occur
have same structural formula but diff arrangement in space
occur when the two double bonded carbon atoms each have two diff atoms/groups attached to them
z isomers
same group either above or below the double bond
e isomers
same groups positioned across the double bond
which is given higher priority
atoms with larger atomic number
cis def
same groups on same side
trans def
same group on opposites sides
electrophilic addition reaction
alkene double bond opens up and atoms are aded to the carbon atoms
why do electrophilic addition reaction happen
because double bond have many electrons ,, easily attacked by electrophiles
electrophiles include
positively charged ions and polar molecules
adding hydrogen to c c double bond produces
alkanes
conditions to produce alkanes form adding hydrogen to carbon carbon double bond
nickel catalyst
150 temp
halogens and alkenes reacts to form
dihalogenoalkanes
what happens when you add brown bromine water to alkene
goes from brown to colorless
steam hydration could make
alcohols
how to make alcohol and conditions
alkenes hydrated by Steam
300 temp
pressure of 60/70 atp
phosphoric 5 acid catalyst
alkenes react with acidified potassium manganate (7)
alkenes are oxidized
alkene w acidified potassium manganate (7) purple
loses colour
alkene reacts w acidified potassium managante to produce
a diol (alcohol w two oh groups)
adding hydrogen halides to unsymmetrical alkenes form
two products
addition polymerisation
double bonds in alkenes open up and join together to make long chains (polymers)
different methods for disposing polymers
- buried
- reused
- burned
landfill is used to dispose of waste plastics when plastics are
- difficult to separate form other waste
- no sufficient quantities to make separation financially worthwhile
- too difficult technically to recycle
diff ways to reuse plastics
- plastics recycled by melting and remolding them
- plastics cracked into monomers and can be used as organic feedstock
why is the honeycomb shape used for catalytic converter
increased
surface area
catalytic converter contains
platinum
rhodium
palladium
on a honey comb mesh of aluminium oxide
waste plastic can be burned and
the heat can be used to generate electricity
the process of burning plastics needs to be carefully controlled to
reduce toxic gases
when burning plastics-waste gases from combustion are passed through
scrubbers which neutralize gases by allowing them to react with a base
why are plastics sorted before they’re burned because
they separate out any materials that will produce toxic gases
the set principles when they design a sustainable polymer manufacturing process are
-reactant molecules used are safe/environmentally friendly ish
-use as few other materials
- renewable raw materials should be used when can be used
-energy use should be kept at a minimum
-use a catalyst often used
-limit waste products made esp the hazardous ones
-make sure lifespan of the polymer is appropriate for its use
biodegradable polymer def
ones that naturally decompose
biodegradable polymers can be made from
renewable raw materials
advantages from using renewable raw materials
-raw materials aren’t going run out like oil
-when polymers biodegrade co2 released
-over their lifetime some plant based polymers save energy compared to oil based plastics
biodegradable polymers need
the right conditions before they’ll decompose
,, still need to collect and separate biodegradable and non biodegradable plastics and ,, more expensive
halogenalkanes are
alkanes with halogen atoms
halogenalkanes can be
primary
secondary
tertiary
halogenalkanes
primary halogenalkanes has
two h atoms and just one alkyl group
secondary halogenalkanes has
one hydrogen atom and two alkyl group
tertiary halogenalkanes has
no hydrogen atoms and three alkyl group
how to form alcohols from halogenalkanes
halogenalkanes hydrolyzed in a nucleophile substitution reaction using water
general equation of hydrolyzing halogenalkanes
x= halogen
R= alkyl group
R-X + H20 arrow R-OH + h+ + x-
how to compare the reactivities of halogenalkanes
mix halogenalkanes w water to form alcohol
put silver nitrate solution in mixture
three test tubes w halogenalkanes ethanol(solvent) and silver nitrate solution
time how long it takes for precipitate to from in each test tube (more quick faster the rate of hydrolysis)
which haloalkane is hydrolyzed the fastest
iodoalkanes
why is iodoalkanes hydrolyzed the fastest
iodalkanes have the weakest bonds due to size of iodine atom ,, weaker bond enthalpy ,, fastest reacting due to fastest hydrolyzing
how quickly diff hakogenalkanes are hydrolyzed depends on
carbon-hydrogen enthalpy change
weaker c-h enthalpy change the faster they react
bond enthalpy depends on
size of halogen ,, larger the halogen the stronger the c-x bond ,, lower the bond enthalpy
explain the halogenalkanes reaction
nucleophilic substitution
halogens more electronegative than c
,, carbon-halogen bond is polar
deltaplus carbon does not have enough electrons ,, attacked by nucleophile which donates e- pair
nucleophile bonds with delta+ carbon of halogenalkanes and substituted for the halogen
three examples of nucleophilic substitution
-halogenalkanes react with (aqueous) potassium hydroxide- under reflux
-cyanide ions react with halogenalkanes- under ethanol and reflux
-halogenalkanes react with ammonia
halogenalkanes react with (aqueous) potassium hydroxide- under reflux form
alcohols
cyanide ions react with halogenalkanes- under ethanol and reflux form
nitriles
halogenalkanes react with ammonia form
amines
general formula halogenalkanes react with aq KOH
R-X + KOH arrow ROH + KX
amines are
organic compounds based on ammonia but one or more h is replaces by an alkyl group
warm a halogenalkanes with excess ethaloic ammonia what happens
ammonia swaps places with the halogen to form a primary amine
if you react a halogenalkane with warm alkali dissolved in ethanol in elimination reactions heated under reflux
alkene formed and water and halogenalkanes
why must the mixture be heated under reflux
volatile stuff will be lost
alcohol homologous series general fromula
CnH2n+1OH
reacting alcohol with PCl5 and HCl
phosphorus pentahloride produces
chloroalkanes
reaction between alcohols and HCl is the fastest if the alcohol is a
tertiary alcohol
reaction between alcohols and HCl is the slowest if the alcohol is a
primary alcohol
alcohols react with compounds containing bromide ions in …. and reaction requires
substitution reaction
hydroxyl group (OH) replaced by bromide so alcohol is transformed to bromoalkane
acid catalyst
you can make iodoalkanes using
alcohol and red phosphorus and iodine
react alcohol and PCl3 phosphorus triiodide
general equation of alcohol and red phosphorus and iodine
3ROH + Pl3 arrow 3RI + H3PO3
alcohols dehydrated to form
alkenes
ethanol dehydrated equations
Ethanol arrow ethene and water
simplest ways to oxidize alcohols
burn them
alcohol completely combusted reaction
alcohol + oxygen arrow carbon dioxide + water
how much alcohols can be oxidized depends on
its structure
primary alcohols oxidized to
aldehydes and then carboxylic acids
secondary alcohols oxidized to
ketones only
tertiary alcohols oxidized to
wont be oxidized
increased alkyl group means
increased stability of carbocation
how to produce ethanal and what it smells like
gently heat ethanol with potassium dichromate (VI) solution and sulphuric acid in a test tube
then an apple smell (ethanal)
what smell is ethanoic acid
vinegar smell
to produce a carboxylic acid
the alcohol has to be vigorously oxidised mixed with an excess of oxidising agents and heated under reflux
tertiary alcohols and postssium dichromate 5
solution stays orange
what is the only way to oxidise tertiary alcohols
is by burning them
what is refluxing used for
to make sure you don’t lose any volatile organic substances
describe how refluxing is done
mixture heated in a flask fitted with a liebig condenser ,, boils and evaporates and is recycled back into flask giving time to react
heating is usually electrical (heating mantle)
distillation separates
substances with different boiling points
separation removes
any water soluble impurities from product
you can remove any traces of water from a mixture
using an anhydrous salt
drying agent def
binds to any water present to become hydrated
types of anhydrous salts
magnesium sulfate
calcium chloride
determine purity
by measuring boiling point
aldehydes have
a hydrogen and and one alkali group attached to the carbonyl carbon atom
ketones have
two alkyl groups attached to the carbonyl carbon atom
test to see if compound is an aldehyde or a ketone
add Benedicts solution
(blue solution of copper (II) ions dissolved in sodium carbonate)
if heated and with an aldehyde with the blue copper (II) ions are reduced to brick red percipitate of copper (I) oxide
if heated with a stone nothing happens because ketones can’t be easily oxidized
primary alcohol’s can be oxidized twice
first forms aldehydes which are then oxidized to form carboxylic acid
[O] what does this show
oxidizing agent
