11.2 Nomenclature Flashcards
What is IUPAC
It is the international organisation of chemists that provide the rules to name molecules so it has the same name everywhere
What is the root of a hydrocarbon chain
It is the longest continuous chain of carbons.
It is named with the prefixes
meth, eth, prop, but, pent, hex
The syllable after the root tells us if there are double bonds, eg if it is ethane there are non but if it is ethene there are.
What are the prefixes added for any side chains
Methyl,
Ethyl
Propyl
Butyl
Pentyl
So eg methylbutane means that the longest continuous carbon chain is 4 carbons, and there is a side chain of one carbon, CH3.
The branch will always have one less hydrogen.
How are ringed hydrocarbons named
They have the prefix cyclo
So eg cyclobutane etc
But they always have the same molecular formula as an alkene despite having ane suffix in their name
What are functional groups
Functional groups are a reactive group attached to the hydrocarbon chain, and this group reacts in the same way despite the length of the chain.
How are alcohols named
With the suffix ol on the end of the alkane
Eg ethanol which has functional group
CnH2n+1OH
Or just CnH2n+2O
so ethanol is C2H5OH
What is the difference between ketones and aldehydes
. Ketones have suffix one
. Aldehydes have suffix al
Eg ethanal CH3CHO
And propanone: CH3COCH3
They both have the formula of an alkane but with an oxygen added O with a double bond
However, aldehydes have the oxygen on the end of molecule, whilst ketones have the oxygen in the middle
Describe structure of carboxylic acids
End with suffix ‘oic acid’
Have a double carbon to oxygen bond
Carbon is bonded to O and OH
COOH
How are halogenoalkanes with more than one functional group or side chains named
If there are two or more halogens on a halogenoalkane, they are named in alphabetical order rather than numerical order
So eg 2-bromo-1-iodopropane
As b is before i in alphabet
And it doesn’t matter what order the numbers are in
If there are multiple of the same substituting group, use prefixes
di, tri, and tetre
Eg 1,2-dichloroethane
So there are 2 chlorines, but they are on different carbons.
How are numbers of functional group alcohols labelled
When writing alcohols, label the carbon that the OH is on by…
Butan-2-ol so put it in the middle of the word
This means the OH is on the second carbon on the chain
How is the number where double carbon bond is labelled on alkenes
In the middle of the word
So eg But-2-ene means the double bond is between the second and third carbon
Same with prop-1-ene
So double bond is between the first and second carbon
Describe structure of halogenoalkanes
In the alkane, one of the hydrogens is swapped with a halogen
no suffix, only prefix which is either
Fluoro, chloro, bromo, iodo,
And these go before the alkane
Eg 2-bromopropane
And the number of the carbon it is attached to is stated before, so the example above has the bromine on the second carbon
With longer carbon chains, you have to say where a side chain or functional group is located on the main chain:
How?
A number tells us position of any branching or functional group:
Eg methylpentane could refer to
2-methylpentane or 3-methylpentale
Because the methyl could be on the second or third carbon.
These are structural isomers
so label the carbon chain, each carbon being 1,2,3 etc.
The carbon on the side of the chain nearest to the first functional group will be labelled 1.
Because the smallest possible number is always used
So 1-bromopropane and
3-bromopropane are the same, however there is no such thing as 3-bromopropane because the smallest possible number of carbons is used.
What is a homologous series
A family of organic compounds with the same functional group, but different carbon chain lengths.
. They all have the same general formula eg CnH2n+2 for alkanes
. Each member of the series differs from the next by CH2
How does the length of the carbon chain affect chemical reactivity, and physical properties of the molecule
. The length of carbon chain has little effect on the reactivity of functional group
. However it affects physical properties..
Eg longer the chain, higher the boiling point because there are more van der walls due to more electrons in longer chains
