naming alkanes, alkenes and alcohols Flashcards
what is an alkyl group
if you remove a hydrogen from an alkane you get an alkyl group. these form side chains
if there is more than one side chain…
two = di-
three = tri-
four = tetra-
different alkyl groups
1 carbon = methyl
2 carbons = ethyl
3 carbons = propyl
4 carbons = butyl
5 carbons = pentyl
6 carbons = hexyl
7 carbons = heptyl
8 carbons = octyl
9 carbons = nonyl
10 carbons = decyl
2-methylpentane
five carbon chains on longest chain (pent)
methyl group is on carbon 2
compound is an alkane so the suffix is ane
2,2-dimethylbutane
4 carbon chains and its an alkane (butane)
2 methyl groups = 2 side chains (dimethyl)
both are on carbon 2 so we write 2,2
4-ethyl-3-methylheptane
longest chain (backbone) is 7 carbons so its heptane
1 ethyl group on carbon 4 and 1 methly group on carbon 3
write in alphabetical order
rules for naming alkanes
to count which carbon the side chain is one you start from the side where the side chain is closest to the ends of the chain. if the side chain is close to one end you start counting from that side.
you cant have a side chain at the start or end of the chain. the carbon chain can go vertical or horizontal
how to name alkanes
1) find the longest back bone of carbon atoms
2) identify side chains
3) identify carbon number 1
4) write the alkyl group in alphabetical order
what is the difference between but-1-ene and but-2-ene
but-1-ene has the carbon double bond on carbon 1 whereas but-2-ene has the carbon double bond on carbon 2
rules for writing alkenes
the double bond has to be part of the main chain
to count which number each carbon is (carbon 1, carbon 2 etc etc) you start from where the carbon double bond is
3-methylhex-2-ene
the longest chain is hexene because it has six carbons with one double bond.
the double bond is on carbon 2 so its hex-2-ene
the methyl group is on group 3 so its written as 3-methylhex-2-ene
4-ethyl-2-methylhex-1-ene
the longest chain is hexene because it has 6 carbons with one double bond
the double bond is on carbon 1 so its hex-1-ene
there is an ethyl group on carbon 4 and methyl group on carbon 2
write the alkyl groups in alphabetical order to get 4-ethyl-2-methylhex-1-ene
what is the difference between alkenes and alkanes in terms of rotation
alkanes can rotate but alkenes can’t. single bonds can rotate
what is a structural/geometric isomer
molecules with the same molecular formula but with different structural arrangement of atoms
for example, butane and 2-methylpropane are structural isomers of eachother. they have the same molecular formula (c4h10)
what is z-isomerism
the two high priority groups on each carbon atom are on the same side of the double bond
