Isomerism Flashcards
what is the name of CH3-CH2-CH2-CH3
butane
what is the name of CH3-CH-CH3
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CH3
methylpropane
what are the differences between butane and methylprropane
- their names are different
- due to their structural formulas being different
what is the similarity between butane and methylpropane
- they both have the same molecular formula
- of C4H10
what is the name given to the relationship between the two molecules
they are structural isomers of each other
what does being a structural isomer basically mean
- they have different structural fromulae
- but have the same molecular formula
what increases in this case as the number of carbon atoms increases
the number of different structural isomers you can have
what are the two main types of isomerism
- chain isomerism
- position isomerism
what does chain isomerism refer to
molecules with different carbon chains (chain lengths)
what are an example of chain isomers and why
- butane and methylpropane
- because their carbon chains are different which give them different codes (but and prop)
- but they are still isomers
what does position isomerism refer to
- molecules with the same functional group attached to different carbon atoms in the same carbon chain
what is an example of position isomerism with propanol and why would they be considered to be position isomers
- propan-1-ol and propan-2-ol
- they have the same carbon chain and functional group
- but a different structural formulae due to the functional group being in a different position
what is an example of two molecules in which chain and position isomerism is being shown (their names)
- 3-methylbutan-1-ol
- pentan-3-ol
what is the structural formula of 3-methylbutan-1-ol
CH2-CH2-CH-CH3
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OH CH3
what is the structural formula of pentan-3-ol
CH3-CH2-CH-CH2-CH3
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OH
what does stereoisomerism refer to
two different ways to arrange atoms or groups of atoms
what is different about stereoisomers
- they have the same molecular and structural fromulae
- but have a different arrangement of atoms
what is the structural formula of but-2-ene
CH3-CH=CH-CH3
what is the first way you can arrange the atoms in but-2-ene
CH3 CH3
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C=C
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H Hwhat is the second way you can arrange the atoms in but-2-ene
H CH3
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C=C
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CH3 Hwhich isomer has the CH3 groups farthest away from each other and why
- the second isomer
- because they are across each other
- as one is on top and the other is on the bottom
what abbreviation would you add to the beginning of that isomers name to indicate this
- trans
- which is latin for across
what term would be used at the beginning of the first isomers name and why
- cis (latin for ‘on this side’)
- because the CH3 groups would be on the both above the double bond
- so they are only at opposite sides not at opposite ends of the molecule
what is this type of stereoisomeric relationship called
- geometric isomers
- also known as cis-trans isomers
why can stereoisomerism only exist in alkenes but not alkanes (specifically), what do alkenes have the alkanes dont)
because there needs to be s C=C bond for the cis and trans isomers to occur
why does there need to be a C=C bond to stereoisomerism
- the presence of that bond leads to restricted rotation
- meaning the groups attached to the C=C cant move around freely
- alkanes dont have double bonds so the hydrogens can rotate freely
is this a stereoisomer of but-2-ene and why
H CH3
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C=C
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H CH3- its not
- because the CH3 groups are on the same side of the C=C double bond
- which makes the carbon chain different as there is no chain of 4 carbon atoms
what is that compound then, compared to but-2-ene and what is its name
- it is a structural isomer of but-2-ene
- and its name is methylpropene
