Topic 6 - Organic Chemistry 1 Flashcards
What is the structure of an alkane?
only a C-C
What is the structure of an alkene?
C=C
What is the structure of an alcohol?
-OH
What is the structure of a carboxylic acid?
-COOH
What is the structure of an ester?
- C=O
- O-C
What is the structure of an aldehyde?
-C=O
-H
(must be on end carbon)
What is the structure of a ketone?
-C=O
must not be on end carbon - something else comes of carbon
What is the structure of a halogenoalkane?
-X
X=halogen
What is the structure of an amine?
-NH2
What is the structure of an amide?
- C=O
- NH2
What does the name of an alkane end in?
-ane
What does the name of an alkene end in?
-ene
What does the name of an alcohol end in?
-ol
What does the name of a carboxylic acid end in?
-oic acid
What does the name of an ester end in?
-yl -oate
What does the name of an aldehyde end in?
-al
What does the name of a ketone end in?
-one
What does the name of a halogenalkane end in?
-ane
What does the name of an amine end in?
-yl amine
What does the name of an amide end in?
-amide
What do you call a 1 carbon chain?
meth
What do you call a 2 carbon chain?
eth
What do you call a 3 carbon chain?
prop
What do you call a 4 carbon chain?
but
What do you call a 5 carbon chain?
pent
What do you call a 6 carbon chain?
hex
What do you call a 7 carbon chain?
hept
What do you call a 8 carbon chain?
oct
What do you call a 9 carbon chain?
non
What do you call a 10 carbon chain?
dec
What do you call an additional CH3 joined to a main carbon chain?
methyl
What do you call an additional CH2CH3 joined to a main carbon chain?
ethyl
What do you call an additional CH2CH2CH3 joined to a main carbon chain?
propyl
What do you call an additional F joined to a main carbon chain?
fluoro
What do you call an additional Cl joined to a main carbon chain?
chloro
What do you call an additional Br joined to a main carbon chain?
bromo
What do you call an additional I joined to a main carbon chain?
iodo
What do you call an additional OH joined to a main carbon chain?
hydroxy
What do you call an additional NH2 joined to a main carbon chain?
amino
What is an isomer?
different arrangement of atoms with the same molecular formula
What are the three types of structural isomers?
carbon chain isomers
positional isomers
functional group isomers
What are carbon chain isomers?
isomers with different lengths of carbon chain
What are positional isomers?
isomers with different positions of functional groups
What are functional group isomers?
isomers with different functional groups
What are geometric isomers?
a type of stereoisomers where there is little rotation around a double C=C bond when there are different groups around the carbons
- cis and trans
- E/Z
What does a molecular formula show?
states numbers of each atom
What does an emperical formula show?
simplest ratio of each atom
What does a displayed structure show?
all the atoms and bonds
What does a structural formula show?
indicates structure but no bonds are shown
What does a skeletal formula show?
shows C-C bonds but no carbon or hydrogen atoms
each kink represents a carbon
What happens in an addition reaction?
two or more substances combine to form one product
What happens in a substitution reaction?
one atom/group replaces another
What happens in an oxidation reaction?
the addition of an oxygen or removal of a hydrogen
What happens in a reduction reaction?
the addition of a hydrogen or removal of an oxygen
What happens in an elimination reaction?
one group/species is eliminated from an organic substance
What happens in a hydrolysis reaction?
water splits an organic molecule into two parts
What happens in a polymerisation reaction?
lots of monomers join to form a long polymer chain
What happens in a condensation reaction?
two or more substances combine and a small molecule is released in the process
(addition + elimination)
alkane + oxygen ->
complete combustion
water + carbon dioxide
What happens in halogenation?
alkane reacts with halogen in UV light
-free radical substitution
three stages involved
1) initiation
2) propagation
3) termination
What happens in the 3 stages of halogenation?
1) initiation -homolytic bond breaking to form 2 free radicals
2) propagation -non-radical molecule reacts with a radical to produce a different non-radical and a different radical (no net gain or loss of free radicals)
3) termination -radicals react together to form uncharged molecules
What is heterolytic bond breaking?
bond breaks unevenly so that one of the bonding atoms receives both electrons from the bonding pair of electrons to form a cation and an anion
eg. X-Y -> X- + Y+
(double headed arrow used)
What is homolytic bond breaking?
bond breaks evenly so that each bonding atom receives one electron from the bonding pair of electrons to form two radicals
eg. X-Y -> X• + Y•
(two single headed arrows used)
What is crude oil?
a mixture of hydrocarbons
-can be known as petroleum
What does fractional distillation do?
convert crude oil into smaller fractions
What are the steps in fractional distillation?
-crude oil is heated and vaporises
-enters fractioning column (with conc gradient -hottest at bottom)
-hydrocarbons rise up through trays and condense at different points (because they have different bps) and run off
bottom -longer chains condense (high bps)
top -shorter chains condense (low bps)
What does cracking do?
breaks long chain hydrocarbons into shorter chain hydrocarbons
What are the two types of cracking?
thermal cracking
catalytic cracking
What does thermal cracking require?
high temps and high pressure
What does thermal cracking produce?
alkenes
What does catalytic cracking require?
zeolite catalyst (Al2O3)
low pressure
low temp
What does reforming do?
converts straight chain hydrocarbons into branched chain hydrocarbons and cyclic hydrocarbons for efficient combustion
Why do straight chain hydrocarbons burn less efficiently?
because of knocking/exploding
When alkanes are burned what pollutants can be produced?
- carbon monoxide (produced from incomplete combustion. Binds with haemoglobin in blood which prevents transport of oxygen -toxic)
- oxides of nitrogen (produced when nitrogen reacts with oxygen at high temps. Can cause acid rain)
- oxides of sulphur (produced when sulphur reacts with oxygen to form SO2 which can form other sulphur oxides in atmosphere. Can cause acid rain)
- carbon particles (produced from incomplete combustion. Can be breathed in and cause coughing, headaches, heart diseases, etc)
What is a catalytic converter?
metals (platinum, rhodium and palladium) spread over honey comb-like mesh
- increases SA for reactions
- removes pollutants (eg. CO, unburned hydrocarbons, etc) when exhaust gases pass over it
Why is a honeycomb structure used in a catalytic convertor?
- increases SA (has more active sites)
- allows gases to pass through
What alternative fuels are there to fossil fuels?
biofuels (during photosynthesis crops take in CO2 and produce sugars/oils which can be burned as fuels -when burned they have no effect on CO2 in atmosphere ∴ carbon neutral)
- bioethanol (ethanol from fermentation of sugar from crops)
- biodiesel (made by refining renewable fats/oils)
- biogas (made by breaking down organic waste matter)
What is the test for double bonds?
bromine water
-changes from orange to colourless
Why are alkenes highly reactive?
-they have a double bond
alkene + oxygen ->
complete combustion
carbon dioxide + water
What is the difference between the complete combustion of a straight chain alkene and a cycloalkene?
straight chains burn cleanly
cycloalkenes burn with a sooty flame
alkene + potassium manganite ->
diol
double bond is oxidised, only occurs in acidic conditions, potassium manganite turns colourless
alkene + halogen ->
dihalogenoalkane
alkene + hydrogen halide ->
halogenoalkane
electrophilic additon, carbocation intermediate formed
What is an electrophile?
a species with a positive charge which is attracted to areas of high electron density
What is a carbocation?
an organic molecule containing a carbon atom which is deficient in one electron so has a positive charge
alkene + steam ->
alcohol
acid catalyst
alkene + hydrogen ->
alkane
nickel catalyst + 150° or palladium catalyst + room temp
Which carbocation is most stable?
tertiary carbocation
-because it has 3 methyl groups that can donate electron density inwards to stabilise positive charge
What does Markovnikof’s rule state?
the hydrogen atom initially adding onto the organic molecule will add to the carbon of the double bond that already has the most hydrogens
-this forms a more stable carbocation and hence the major product
What can be done with waste polymers?
- recycled (melted + remoulded)
- incinerated (burned to release energy -toxic gases can be released in the process)
- reused as feedstock in cracking
- buried in landfill
What solutions are there to polymer disposal?
- limit waste products
- develop biodegradable polymers (expensive)
- minimise energy use (eg. use catalysts)
- use less other materials
- use more renewable materials
What are the properties of halogenoalkanes?
- bps higher than alkanes but lower than alcohols (can from London forces and PD interactions)
- generally insoluble in water (no H-bonds except fluoroalkanes)
- readily react with nucleophiles (in nucleophilic substitution, nucleophiles attack their 𝛿+ carbon)
What is a nucleophile?
a negative ion/molecule with a lone pair of electrons that attacks areas of positive charge
halogenoalkane + aqueous potassium hydroxide ->
alcohol (+halide ion)
nucleophilic substitution where OH- (from water) acts as nucleophile and attacks 𝛿+ carbon
halogenoalkane + alcoholic potassium hydroxide ->
alkene (+water +halide ion)
elimination where OH- acts as a base and takes H from halogenoalkane
halogenoalkane + aqueous silver nitrate ->
alcohol
(reacts with water, substitution)
precipitate forms from silver nitrate (white = AgCl, cream = AgBr, yellow = AgI)
halogenoalkane + potassium cyanide ->
nitrile
reflux, CN- acts as nucleophile
halogenoalkane + ammonia ->
amine
heated in sealed vessel, concentrated ammonia in excess
Do chloro, bromo or iodo alkanes react the fastest?
iodoalkanes have the fastest rate
-iodine is the largest atom so forms longer (weaker) bonds which require less energy to break
chloroalkanes have the slowest rate
-chlorine is the smallest atom so forms shorter (stronger) bonds which require more energy to break
Do primary, secondary or tertiary halogenoalkanes react the fastest?
tertiary halogenoalkanes have the fastest rate
-form a more stable carbocation
primary halogenoalkanes have the slowest rate
-form unstable carbocation so waits to be attacked by water molecule rather than forming a carbocation -this takes longer
What are the properties of alcohols?
- high bps (can H-bond)
- shorter chain alcohols are soluble in water (can H-bond with water) whereas long chain alcohols are insoluble in water (long hydrophobic tails disrupt potential H-bonds)
- reactive (act as nucleophiles due to their lone pair of electrons on the oxygen)
alcohol + oxygen ->
combustion
carbon dioxide + water
alcohol + pentachloride ->
chloroalkane (+POCl3 +HCl)
alcohol + sulfuric acid + potassium bromide ->
bromoalkane (+ water)
acid and potassium bromide produces hydrogen bromide, which then reacts with the alcohol
alcohol + red phosphorus + iodine ->
iodoalkane (+HPO3)
(reflux, phosphorus and iodine produce phosphorus(III)iodide which then reacts with the alcohol, iodoalkane can be distilled off)
alcohol + phosphoric acid ->
(H3PO4)
alkene + water
elimination, phosphoric acid acts as a catalyst
What oxidising agent is used to oxidise alcohols?
potassium dichromate (VI) (K2Cr2O7)
What is produced when a primary alcohol is oxidised?
aldehyde (partial oxidation) carboxylic acid (full oxidation)
What happens in the partial oxidation of a primary alcohol?
- distillation
- potassium dichromate and H+ present
- aldehyde and water formed
How can you test for an aldehyde?
add Benedict’s/Fehling’s solution
+ve result: colour change from blue to brick red
-Cu2+ ions are reduced to CuO (a red ppt)
What happens in the full oxidation of a primary alcohol?
- reflux (vertical condenser with open top)
- potassium dichromate and H+ present
- carboxylic acid and water produced
How can you test for a carboxylic acid?
add calcium/sodium carbonate
+ve result: fizzing and bubbling
What is produced when a secondary alcohol is oxidised?
ketone
What happens in the oxidation of a secondary alcohol?
- reflux
- potassium dichromate used as oxidising agent
- ketone produced
Why can tertiary alcohols not be oxidised?
it can not form any oxygen double bonds (because there are methyl and hydroxy groups attached to carbon)
What is a separating funnel used for and how is it used?
to separate an organic product and water (and any soluble impurities)
- product and water are shaken in funnel
- organic layer and aqueous layer (containing impurities) don’t mix (are immiscible) so separate into 2 layers
- the layers can be run off separately
What can anhydrous salts be used for and how are they used?
to remove traces of water
- salt is used as a drying agent by binding to water molecules to become hydrated
- mixture can be filtered afterwards to remove salt
How do anti-bumping granules prevent bumping?
- distribute heat more evenly
- provide a surface for bubbles to form
