Organic Flashcards
General formula
Algebraic formula that can describe any member of a family of compounds
Empirical form
Simplest whole number ratio of Elmer’s in a compound
Molecular formula
Acc n.o of atoms of each element in a molecule eg C4 H10 O
Structural formula
Shows the atoms carbon by carbon with attached hydrogens and functional groups eg CH3CH2CH2
Skeletal form
Shows bonds of carbon skeleton and any functional groups
Hydrogen and carbon atoms aren’t shown
Displayed
Shows how all atoms are arranged and all bonds between them
Homologous series
Group of compounds with same functional group and similar chemical properties
How does each successive member of homologous series differ
By a CH2 group
Functional group
Part of mol that determines how it reacts
What is nomenclature
Naming of organic molecules by IUPAC
Number of carbons for each prefix
Meth - 1 hex - 6
Eth - 2 Hept - 7
Prop - 3 Oct - 8
But - 4 Non - 9
Pent -5 Dec - 10
Alkanes functional group and suffix
C-C
- ane
Alkenes
C=C
-ene
Haloalkanes func group and prefix and suffix
C-X (X is halogen)
Chloro
Bromo
Fluoro
Iodo
- ane
Alcohol
OH
-anol
Aldehyde
CHO. O
||
C
\
H
Carbonyl group on the end of chain
- anal
Ketone
C(O)H
Carbonyl group in middle
- anone
Carboxylic acid
COOH
- anooic acid
Rules for naming
1)
Find longest carbon chain + count
To decide prefix ( meth eth prop etc)
2)
Look for func group and decide suffix (anol ene ane)
3)
Number func group w lowest number
4
Look for additional things attached to chain
5
Number additional things
Methyl group
CH3
Ethyl
CH2 - CH3
Where does number come
Before it’s thing in the chain
Prefix for 2 3 4 halogen
Di
Tri
Tetra
How are things arranged
Alphabetically
How do you number something with 2 of a thing eg carbon w 2 chlorine’s attached
2, 2 - di Choro
Between letters and numbers
Dash
Between numbers and numbers
Comma
How are alcohol groups named
Numbering occurs within the name
Eg pentan - 2 - ol
Structural isomers
Molecules with same molecular formula but different structural formula
Can be done by adding methyl groups
Functional group isomers
Molecules have same molecular formula but different functional groups
Chain isomers
Differ the arrangement of the hydrocarbon chain
Eg adding a branched methyl group
Positional isomers
Have diff postions of functional group on the hydrocarbon chain
Eg 1- chloro butane and 2 chloro butane
Stereoisomers def
Same structural formula but different arrangements of atoms in space
Single covalent bonds are….
Fully rotational
Double covalent bonds have ..
Restricted rotation
So isomers with restricted movement have their atoms …
Either on the same side or opposite sides
What are these isomers called
Geometrical isomers
If atoms on the same side they are ….. isomers
Cis isomers / Z isomers
Is atoms are on opposite sides they’re
Trans/ E isomers
geometric isomers aka
e/z isomers
What 2 conditions have to be met for Alkene to have e/z isomer
Double bond C —> must be attached to 2 diff groups/atoms
At least one of the groups must be the same on both carbon atoms on the double bond
Groups on Z isomer
The same side
Groups on E isomer are on the
Opposite side
Trans isomers
When naming E/Z isomers you put the…
E or Z before the isomer name
First CIP rule for E/Z isomers
Look at the atoms attached to the carbons on either side of the double bond
Element with greatest atomic number is given priority
So an isomer is an E isomer if via CIP
The highest priority groups are on opposite side
An isomer is a Z isosmer via CIP if
The highest priority groups are on the Same side
what is a hydrocarbon
mol that contains carbon and hydrogen atoms only
saturated …
singe carbon - carbon bonds
alkanes
unsaturated …
double carbon=carbon bonds
alkenes
what is crude oil
mixture of alkanes
sep crude oil by….
fractional distillation using fractionating column
how does frac dist work (hint bp)
sep alkanes based on bp that is determined by length of hydrocarbon chain
longer chain=higher bp
more van dew waals forces
frac column - how does it cool
heat crude oil
vapour in
crude oil vapour rises and will cool
short chains at top of colum - cooler
long chain at botton where its hotter
as it cools vapour will condesne when they reach their bp –> collected as fractions
cracking
breaking long chained alkanes into short more useful alkenes that are higher in demand and make more money due to low supply and high demand is short alkames and alkenes worth lots of money.
complete combustion prod
carbon dioxide and water
incomplete combustion prod
carbon monoxide (CO) and water
or carbon and water
test for alkenes
bromine sol
orange to colourless
alkenes used …
chemical feed stock
feuls
plastics
what is petroleum and naphtha
crude oil
Naptha is petrol
2 types of cracking
thermal cracking
catalytic cracking
thermal cracking
high temp (700-1200k) and high pressure (7000kpa)
products :alkenes a lot more than catalytic
Applications: ethene used for making polymers and ethanol
catalytic cracking
uses zeolite catalyst
high temp
slight pressure
produces aromatic, branched and cyclic hydrocarbons and used to make motor fuels and alkenes but far less than in thermal
alkanes make great fuel bc and uses of fuels
burning small amounts rel lots of energy
for central heating and fuel to car engines
downside of alkanes
rel lots of pollutants
Steps of free radical substitution
Initiation
2 propagation
Termination
Overall equation for methane + chlorine
Ch4 + CL2 —> CH3CL + HCL
Initiation step for chlorine and methane
CL2 —-> cl . + cl.
. = free radical
Free radical meaning
Species w unpaired e-
conditions for initation and describe whagt happens
in presense of uv light breaks
cl - cl bond - via homolytic fission so each atom gets one e- from covalent bond
describe propogation part 1 w methane and give equation
The chlorine free radicals are very reactive and remove
an H from the methane leaving a methyl free radical
CH4 + Cl. –> HCl + .CH3
describe propogation part 2 w methane and give equation
The methyl free radical reacts with a Cl2 molecule to
produce the main product ( prod w one less h replaced w cl and another Cl free radical
what is common in all propogation steps
All propagation steps have a free radical in the reactants and in the products.
how do cl free radicals lead to chain reaction
As the Cl free radical is regenerated, it can react with several more
alkane molecules in a chain reaction.
describe termination and give equation
2 radicals combine to form neutral mol
cl. + cl. –> cl2
.CH3 + Cl . –> CH3Cl
.CH3 +. CH3 –> CH3CH3
this stops the reaction
What group will take priority using CIP rules for steroisoners
Group with highest atomic number takes priority
Homologous series have the same
Same general formula
Same chemical properties
same functional group
General formula for alkane
CnH2n+2
General formula for cycloalkane and Alkene
CnH2n
General formula for nalogenoalkanes
CnH2n+1X
X is the halogen
General formula for alcoholism
CnH2n+1OH
General formula for aldehyde and ketones
CnH2nO
C double bond to O and then H happens at the end of the chain (carbonyl group)
On ketone c double o bond in the middle
General formula and functional group for carboxylic acid
CnH2nO2
R - C double O
THEN O -H at bottom
General formula and fund group of amine
CnH2n+3n
R - NH2
General form for nitriles
CnH2n-1
R - C tripled bond to N
Usually when drawing functional group isomers you will have to draw…
An alkene ad a cycloalkane
An aldehyde and ketone
An alcohol and ether (C-O-C)
Carboxylix acid and ester COOC c double bonded to O
Physical properties of alkanes
Non polar
Weak van den walls forces = now boiling point
Van her walls increase in strength if chain length increases boiling point increases
Branching of chain gives lower bp due to weaver vow
Insoluble in water as water is a polar solvent and acuanes are non polar
Uses for alkanes
Quite unreactive because c-c bonds strong flammable so used as fuels
Used as a lubricant and to make other molecules like alkenes and halogenoaljanes
Order of fractions from crude oil
@Top:
Petrol, kerosene, diesel oil, lubricating ail, fuel oil, bitumen (C70)
Properties of shorter alkanes
Found at top of fractionating column where it cooler
Lower bp, more valitale, more flammable, less viscous more runny) and less coloured.
How
Does thermal cracking work
Thermal cracking involves breaking a carbon-carbon bond.
● The bond breaks by heterolytic fission, so one electron from the bonding pair goes to each half of the molecule.
● This forms fragments of the original molecule called free radicals (species with an unpaired electron).
● In order to become more stable, the fragments become an alkane and an alkene (there are not enough hydrogens to form two alkanes)
Structure of zeolite catalyst
Honey comb
Reactivity of any mol depends on
Bond enthalpy The bond enthalpies of C—C bond and C—H bond are quite high that makes it difficult to be broken. A C—C bond has a bond enthalpy of 342 kJ/mol. A C—H bond has a bond enthalpy of 412 kJ/mol.
Bond polarity
Alkanes are non polar as Carbon and Hydrogen have similar electronegativities. Due to this, the bonds are difficult to be broken and this makes alkanes unreactive except towards free radicals. But alkanes reactive with oxygen in combustion reactions and with halogens in substation reactions (in the presence of sunlight).
Incomplete combustion equation and examples
alkane + oxygen → carbon monoxide + water alkane + oxygen → carbon + water
For example:
propane + oxygen → carbon monoxide + water C3H8(g) + 31⁄2O2(g) → 3CO(g) + 4H2O(g)
propane + oxygen → carbon + water C3H8(g) + 2O2(g) → 3C(s) + 4H2O(g)
Most common pollutants of combustion and incomplete combustion
Carbon monoxide - poisonous gas
Carbon particulates-soot-asthma+ cancer
Carbon dioxide and water vapour- green house gases
Sulphur dioxide _ acid-rain- S+O2
Nitrogen oxides - N2+o2 —> 2NO
Unburnt hydrocarbons - rise up into atmosphere and react w nitrogen oxides prod photochemical smog
Nitrogen oxide as pollutant
Nitrogen oxides are produced due to high temperatures inside petrol engines. The oxides can dissolve in water in the atmosphere to form nitric acid and resulting in acid rain. Nitrogen oxides also contribute to photochemical smog
Sulphur dioxide as a pollutant
Sulphur dioxide is produced by the combustion of fossil fuels which contain sulphur impurities. Sulphur dioxide dissolves in water in the atmosphere to produce acid rain.
What is the greenhouse effect + why is it getting worse
The greenhouse effect is a naturally occurring process that has kept the Earth at a warm enough temperature for life to evolve and sustain.
However since the industrial revolution the massive increase in the combustion of fossil fuels has dramatically increased carbon dioxide levels in the atmosphere, leading to an enhanced greenhouse effect which causes the Earths average temperature to increase
Earth gets warmed up by visible radiation infrared from the sun, this can penantrale the gases in the atmosphere. Infrared emitted by earth, some passes into space,some trapped by gg in the atmosphere this traps radiation this warms the earth-warme enough tosupport life but now too warm due to fossil fuels releasing lots of co2
Equation for nitrogen oxides
N2+O2→2NO
N2 + 2O2→2NO2
Where are nitrogen oxides produced and what do they produce
In car engine
NO is toxic and produces smog. NO2 is toxic and produces acid rain.
How can harmful gases produced by combustion be removed and what are they turned into
With equations
These harmful gases can be removed by using catalytic converters to convert these
gases in exhaust to carbon dioxide, nitrogen and water.
2CO + 2NO→2CO2 + N2
C8H18 + 25NO→ 8CO2 + 12.5N2 + 9H2O
Catalysts in catalytic converter
platinum and rhodium
Expensive metals
How to reduce costs of expensive metal catalysts used in catalytic converters
In order to reduce the cost and increase the effectiveness, the metals are coated onto a ceramic honeycomb, giving an enormous surface area for the reaction. The reactions take place on the surface of the catalyst
2 reactions in catalytic converter And their equations
In the catalytic converter, Nitrogen oxide and carbon monoxide react together. While the nitrogen oxides are converted to harmless nitrogen, the cabon monoxide is converted into carbon dioxide.
2CO(g) + 2NO(g)→N2(g) + 2CO2(g)
• Unreacted hydrocarbons also react with nitrogen oxides to form
nitrogen and carbon dioxide and water.
C8H18 + 25NO→12.5N2 + 8CO2 + 9H2O
How is sulphur dioxide formed and what does it go onto form
Petroleum fractions, coal and natural gas contain sulphur impurities that burn in the presence of oxygen to form sulphur dioxide.
S+O2 → SO2
CH3SH+ 3O2 → SO2 + CO2 + 2H2O
The sulphur dioxide combines with oxygen and water in the atmosphere to form sulphuric acid, which in turn produces acid rain.
SO2(g) +0.5O2(g) +H2O(l)→H2SO4(l)
Removal of sulphur dioxide from waste gas happens during…
Flue gas desulfurisation - In power stations that burn coal or natural gas the sulphur dioxide that is produced is removed from the flue (waste) gases through a chemical reaction.
1st step of flue gas desulfuration
Calcium oxide, which is a base, neutralises the acidic sulphur dioxide. It is then further oxidised to form calcium sulphate.
The overall reaction is;
CaO(s) + 2H2O(l) + SO2(g) + 0.5O2(g) → CaSO4.2H2O(s)
flue gas desulfuration what happens to products formed
Calcium sulphate is then sold and used to make plasterboards and builders plaster.
Alternative to using calcium oxide in flue gas desulturisation + equation + downsides
Alternatively, calcium carbonate can be used, however this process produces carbon dioxide. - this is a green house gas
CaCO3(s) + SO2(g) + 0.5O2(g) → CaSO4(s)+ CO2(g)
Is crude oil renewable or non renewable?
Non renewable
To conserve crude oil what is done
To conserve crude oil, alternative fuels are found by researchers.
• Alcohols and bio-diesel are examples of fuels with plant origin and hence, are renewable.
• Alcohol is produced by fermentation of sugars from plants and bio-diesel is produced by reacting vegetable oils with a mixture of alkali and methanol.
• Biodiesel is more carbon neutral which means that the emission of green house gases is reduced
• Hydrogen fuel cells use hydrogen gas and oxygen gas as its reactants and produce energy and water. This is an example of carbon neutral fuel
what is a halogenalkane
alkane with halogen
how can halogenoalkanes be classfied
Halogenoalkanes can be classified as primary, secondary or tertiary depending
on the number of carbon atoms attached to the C-X functional group.
what is a primary halogenalkane
One carbon attached to the
carbon atom adjoining the
halogen
what is a secondary halogenalkane
Two carbons attached to the
carbon atom adjoining the
halogen
what is tertiary halogenalkane
Three carbons attached to the
carbon atom adjoining the
halogen
what reactions do halogenoalkanes undergo
Halogenoalkanes undergo either
substitution or elimination reactions
what is substitution reaction
swapping a halogen atom for another atom or groups of atoms
eg methane + chlorine —> chloromethane + hydrogen chloride
what is a nucleophile
species w lone pair of electrons thta will attack an electron deficient species
has a neg charge
They are attracted to a positive charge or dipole on another molecule
3 nucleopiles
Common nucleophiles are hydroxide ions -:OH, ammonia :NH3, and cyanide ions -:CN
nuc sub reac beneficial bc
Nucleophilic substitution reactions are useful as they introduce new functional groups on to a molecule. This allows synthesis of specific molecules, eg pharmaceutical drugs.
2 headed arrows in mechanisms show
movement of 2 e-
why can nuc attack halogenoalkane
The polarity of the carbon-halogen bond makes it susceptible to nucleophilic attack.
general equation for nuc sub
H H
| |
R - C - X + :Nu- –> R - C - Nu + :X
| |
H H
halide ion prod by nuc sub of halogeno alkane known as
leaving group
explain the mech for nuc sub
arrow from middle of delta pos C - X delta neg bond towards the x
arrow from nuc to delta pos carbon
nuc takes place of halogen - x
x now halide ion w lone pair and neg charge
explain bond polarity of group 7
Going down group 7, the polarity of the bond decreases.
This is because the electronegativity of the halogens decreases going down the group.
The dipole on a halogenoalkane is not strong enough to form hydrogen bonds and so haloalkanes are not soluble in water.
The intermolecular forces between haloalkane molecules are dipole-dipole forces and van der Waals forces.
least to most electro neg halogens
fluroine
chlorine
bromine
iodine
explain boiling points of halogenoalkanes
Boiling points of halogenoalkanes increase with:
Increasing carbon chain length
The further down the group the halogen is.
Both factors increase the number of electrons in the molecule and therefore increase the strength of the van der Waals forces.
Halogenoalkanes have higher boiling points than alkanes with similar chain lengths due to their higher molecular masses and polarity.
Branching of the halogenoalkane molecule lowers the melting point.
explain bond enthalpies of group 7
Going down group 7, the carbon-halogen bond enthalpy decreases.
Going down the group, the atomic radius of the halogen increases.
Fluorine being the smallest attracts the bonding pair of electrons most strongly towards its nucleus, giving the bond its strength.
Iodine being the largest atom has the weakest bond as the bonding pair of electrons is furthest from its nucleus.
hydrolosis of halogenalkanes occurs when
When halogenoalkanes react with an aqueous solution hydroxide ions, a nucleophilic substitution reaction occurs, producing an alcohol and a halide ion.
For example,
1-iodopropane + hydroxide Propan-1-ol + iodide
what is the
chnage in funtional group
reagent
conditions
mechanism
and type of reagent
for nuc sub w aqeous hydroxide ions
Change in functional group: halogenoalkane –> alcohol
Reagent: potassium (or sodium) hydroxide
Conditions: In aqueous solution; Heat under reflux
Mechanism: Nucleophilic Substitution
Type of reagent: Nucleophile, OH-
why is aqeous conditions important for nuc sub w oh- ion
The aqueous conditions needed
is an important point. If the
solvent is changed to ethanol
an elimination reaction occurs.
what is the
chnage in funtional group
reagent
conditions
mechanism
and type of reagent
for nuc sub w cyanide ions
Change in functional group: halogenoalkane —> nitrile
Reagent: aqueous alcoholic potassium cyanide - ethanolic
Conditions: Heating under reflux
Mechanism: Nucleophilic Substitution
Type of reagent: Nucleophile, :CN-
what does nuc sub w cyanide ions due to carbon chain and name of product formed
This reaction extends the carbon chain by one carbon, which must be reflected in the name of the product. The product will be named with the suffix –nitrile.
products of Chloroethane + potassium cyanide
propanenitrile + potassium chloride
what is the
chnage in funtional group
reagent
conditions
mechanism
and type of reagent
for nuc sub w ammonium ions
Change in functional group: halogenoalkane –> amine
Reagent: NH3 dissolved in ethanol
Conditions: Heating under pressure (in a sealed
tube)
Mechanism: Nucleophilic substitution
Type of reagent: Nucleophile, :NH3
how to name product of reaction of nuc sub with ammonia ion
The product is an amine R-NH2.
Amines are named with the suffix –amine.
The stem of the name is named as alkyl.
products of bromopropane + ammonia
Bromopropane + Ammonia –> propylamine + ammonium bromide
CH3CH2CH2Br + 2NH3 —-> CH3CH2CH2NH2 + NH4Br
explain mechanism of nuc sub w ammonia
arrow from middle of C-X bond (respective delta neg and positive charges)
arrow from nh3 nuc to c
h
| so now hal ion formed w N- h
|
h takin its place
n from nh3 above msut have postive charge
then arrow from nh3 nuc toward bottom h on nh3 drawn above
and arrow from middle of drawn bond to postitive n
what is the
chnage in funtional group
reagent
conditions
mechanism
and type of reagent
for elimination w oh ions
Change in functional group: halogenoalkane
alkene
Reagents: Potassium (or sodium) hydroxide
Conditions: In ethanol ; heat
Mechanism: Elimination
Type of reagent: Base, OH
differences in solvent for nuc sub and eliminatron
Note the importance of
the solvent to the type of
reaction here.
Aqueous: substitution
Alcoholic: elimination
describe mech for elimnation w oh
https://chemrevise.files.wordpress.com/2021/02/3.3-revision-guide-halogenoalkanes-aqa.pdf
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what is ozone and its benefits
The naturally occurring ozone (O3
) layer in the upper
atmosphere is beneficial as it filters out much of the sun’s
harmful UV radiation
what distrupts ozone layer
man made cfs (chloroflurocarbons)
how do cfs distrupt ozone layer
(CFC’s) caused a hole to form in the ozone
layer. Chlorine radicals are formed in the upper atmosphere when energy from
ultra-violet radiation causes C–Cl bonds in chlorofluorocarbons (CFCs) to break forming chlorine free radical
equation to show chlorine rad formation in cf2cl2
CF2Cl2 –> CF2Cl . + Cl.
what does chlorine free radical go on to do and give equation
break down ozone mol to o2 mol
Cl. + O3 –> ClO. + O2
chlorine rad acts as a _____ and so it not ____ __ so can be ______ and give equation for this
chlorine rad acts as a catalyst and so is not used up and can be regenerated
ClO. + O3 –> 2O2
overall equation for ozone dep
2 O3 –> 3 O2
what is now used instead of cfcs and why are they better
HFCs (Hydro fluoro carbons) e.g. CH2FCF3 are now used for refrigerators
and air-conditioners. These are safer
as they do not contain the C-Cl bond
The C-F bond is stronger than the C-Cl bond and is not affected by UV.
