Module 4: Core Organic Chemistry Flashcards
What is the first rule for naming branched alkanes?
Find the longest continuous carbon chain and name it- this is the STEM (methane, ethane, propane etc)
What is the second rule for naming branched alkanes?
Name the chain coming off (Alkyl group- methyl, ethyl, propyl etc)
What is the formula for alkyl groups?
C n H 2n+1
What is the third rule for naming branched alkanes?
Count which carbon the alkyl group is on- this is the PREFIX
What is the fourth rule for naming branched alkanes?
If the same alkyl group appears more than once add di, tri, tetra etc… (whichever is relevant)
What is the fifth rule for naming branched alkanes?
The chains are named alphabetically regardless of the number
What is the sixth rule for naming branched alkanes?
Any functional groups go at the end- this is called the SUFFIX (if the SUFFIX begins with a vowel remove the ‘E’ from the end of the STEM)
What is a homologous series?
A homologous series is a sequence of compounds with the same functional group and similar chemical properties with each successive member differing by CH2
What is the general formula for alkanes?
C n H 2n+2
What is the general formula for alkenes?
C n H 2n
What is the general formula for cycloalkanes?
C n H 2n
What are the two types of structural formulas?
Displayed and skeletal
What is a hydrocarbon with one carbon stem?
Meth
What is a hydrocarbon with two carbons stem?
Eth
What is a hydrocarbon with three carbons stem?
Prop
What is a hydrocarbon with four carbons stem?
But
What is a hydrocarbon with five carbons stem?
Pent
What is a hydrocarbon with six carbons stem?
Hex
What is a hydrocarbon with seven carbons stem?
Hept
What is a hydrocarbon with eight carbons stem?
Oct
What is a hydrocarbon with nine carbons stem?
Non
What is a hydrocarbon with ten carbons stem?
Dec
What are isomers?
Molecules with the same molecular formula but different structural formulas
What is chain isomerism?
When the chain of carbons is arranged differently
What is position isomerism?
When the placement of a functional group changes
What are aliphatic hydrocarbons?
Carbon chains
What are alicyclic hydrocarbons?
Carbon atoms in a ring structure
What are aromatic hydrocarbons?
Carbon atoms involving benzene structure
What are alkenes?
Double bond between carbon atoms
What are alkynes?
Triple bond between carbon atoms
What are alcohols?
Hydrocarbons with the functional group -OH
What are haloalkanes?
Hydrocarbons with a halogen as a functional group (chlorine, flourine, bromine)
What are aldehydes?
A hydrocarbon with a carbon atom double bonded to an oxygen atom and single bonded to a hydrogen atom, suffix of -al (ethanal)
What are ketones?
A hydrocarbon where a carbon is double bonded to an oxygen atom
What are carboxylic acids?
A hydrocarbon where an carbon is double bonded to an oxygen atom and single bonded to an -OH group
What is the difference between saturated and unsaturated?
Saturated molecules have no double bonds and cannot make any more bonds between atoms, unsaturated molecules have double bonds and can make more bonds between atoms
How does fractional distillation work?
The longer the chain length, the more London forces and surface contact between the molecules, so the longer the molecule is the higher the boiling point is
What is a sigma bond?
Overlap of orbitals that can freely rotate
Why are alkanes unreactive?
Strong covalent bonds and low polarity
What is oxidised in combustion?
Fuels
What happens to fuels when they react with oxygen?
Carbon -> carbon dioxide
Hydrogen-> water
What are the products from complete combustion?
Carbon dioxide water
What are the products from incomplete combustion?
Carbon monoxide, carbon and water
What is the algebraic formula of complete combustion?
CxHy + (x+y/4)O2 -> xCO2 + y/2 H2O
What is free radical substitution?
A substitution reaction involving an atom called a radical- an atom with a single unpaired electron
What is a substitution reaction?
A chemical reaction in which an atom, ion, or group of atoms or ions in a molecule is replaced by another atom, ion, or group
What order do free radical substitution reactions happen in?
Initiation, propagation, termination
What is initiation in free radical substitution?
When the chain of substitution reactions is started by UV light breaking a chlorine/bromine molecule into free radicals
What is homolytic fission?
When a diatonic atom (such as chlorine, Cl2) breaks into 2 chlorine radicals
What is propagation in free radical substitution?
Reactions which keeps the chain going (one radical on each side of the reaction)
What is termination in free radical substitution?
Reactions which remove free radicals from the system and do not replace them
What is a negative aspect to using free radical substitution in a lab?
No controlling what product form
How can free radical substitution be slightly controlled in a lab?
Limiting one reacant e.g. Chlorine radicals
Why do alkenes have weaker intermolecular forces?
Because the double bond puts a kink in the chain, therefore reducing surface contact and interaction of London forces
How do you name alkenes?
Same as alkanes, except you have to find the longest carbon chain that contains a double bond(s)
How many bonds can a carbon atom make?
4
How many bonds can a hydrogen atom make?
1
What bonds are present in a double bond?
Sigma bond and pi bond
Why can alkenes open their double bond to become saturated alkanes?
Because the pi bond is weaker than the sigma bond
What is stereoisomerism?
A molecule with the same structural formula but different arrangement in space
What is cis-trans isomerism?
A form of isomerism that requires a double bond between carbons and different groups attached to each carbon in the double bond, must one of the groups must be a hydrogen (cis - same side, trans -different sides)
What is E-Z isomerism?
A form of isomerism that requires a double bond between carbons and different groups attached to each carbon in the double bond (Z - same side, E - opposite sides)
What is the Cahn-Ingold-Prelog priority rule?
Looking at what’s DIRECTLY attached to the carbon in the double bond to assign it E or Z for stereoisomerism; the atom with the higher atomic number has priority
How does stereoisomerism effect the physical properties of compounds?
An increase in surface contact increases intermolecular forces, therefore increases the energy needed to break those forces (and increases density)
What is hydrogenation?
When hydrogen (H2) is added to an alkene to form an alkane
What do addition reactions require?
A nickel catalyst
What is a mono-unsaturated alkene?
When there is only 1 carbon-carbon double bond
What is a poly-unsaturated alkene?
When there are 2 or more carbon-carbon double bonds
What happens when water reacts with alkenes?
Alcohol alkanes are formed
What happens when alkenes react in addition reactions?
The pi bond breaks to form an alkane
Why are alkenes more reactive that alkanes?
Because they are unsaturated and have a weak pi bond
What reactions do alkanes undergo?
Combustion, substitution
What reactions do alkenes undergo?
Combustion, addition
What is an electrophile?
A species with a whole or partial positive charge; they are electron pair acceptors
Why are alkenes ‘attacked’ by electrophiles?
Because of the high electron density of the double bond
What is a curly arrow?
A diagram representation of the movement of a single/a pair of electrons
What is heterolytic fission?
When a compound with a covalent bond between two different chemical species is broken in unequally, resulting in one atom retaining the pair of electrons
What is a carbocation?
A carbon atom without a pair of electrons as a result from the pi bond breaking open during heterolytic fission
What is an addition reaction called when an electrophile is involved?
Electrophilic addition
What is Markovnikoffs’ rule?
When a hydrogen halide reacts with an unsymmetrical alkene the hydrogen will attach to the carbon (of the double bond) with the most hydrogens and least carbons attached
In Markovnikoffs’ rule, why is the majority product formed rather than the minority product?
Because it is more energetically stable, therefore less activation energy is needed
Name the products formed from Markovnikoffs’ rule
Majority and minority (primary and secondary depending on which comes first)
What is addition polymerisation?
When an alkene (monomer) undergoes an addition reaction with itself to form a polymer
What happens in addition polymerisation?
The pi bonds opens up to bond with other monomers
What are the conditions requires to form poly(ethene)?
200 degrees centigrade, 2000 atmospheres pressure, small amount of oxygen free radical
What is the difference between linear and non-linear polymers?
Branching; linear polymer gas more surface contact therefore stronger intermolecular forces
What decides the properties of a polymer?
Chain length, side groups (polarity increases chain strength), branching
What is cross linking in polymers?
Covalent bonds between monomers that make the polymer difficult to melt
What are thermoplastics?
No cross linking, weak forces in the chain so easily broken by heating
What are thermosets?
Lots of cross linking, strong covalent bonds so keeps it shape when heated
What is stereoisomerism?
Alkenes with the same molecular formula but a different arrangement in space
Why does stereoisomerism occur?
Because the pi bond in the double bond restricts the rotation
What is E/Z isomerism?
When a molecule has a carbon-carbon double bond and different groups attached to each carbon of the double bond
What is cis-trans isomerism?
When a molecule has a carbon-carbon double bond and different groups attached to each carbon of the double bond, however there must be a hydrogen group on each of the carbons
