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Chemistry 6 - Organic Chemistry > Isomerism > Flashcards

Flashcards in Isomerism Deck (28)
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1
Q

what is the name of CH3-CH2-CH2-CH3

A

butane

2
Q

what is the name of CH3-CH-CH3
|
CH3

A

methylpropane

3
Q

what are the differences between butane and methylprropane

A
  • their names are different

- due to their structural formulas being different

4
Q

what is the similarity between butane and methylpropane

A
  • they both have the same molecular formula

- of C4H10

5
Q

what is the name given to the relationship between the two molecules

A

they are structural isomers of each other

6
Q

what does being a structural isomer basically mean

A
  • they have different structural fromulae

- but have the same molecular formula

7
Q

what increases in this case as the number of carbon atoms increases

A

the number of different structural isomers you can have

8
Q

what are the two main types of isomerism

A
  • chain isomerism

- position isomerism

9
Q

what does chain isomerism refer to

A

molecules with different carbon chains (chain lengths)

10
Q

what are an example of chain isomers and why

A
  • butane and methylpropane
  • because their carbon chains are different which give them different codes (but and prop)
  • but they are still isomers
11
Q

what does position isomerism refer to

A
  • molecules with the same functional group attached to different carbon atoms in the same carbon chain
12
Q

what is an example of position isomerism with propanol and why would they be considered to be position isomers

A
  • 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
13
Q

what is an example of two molecules in which chain and position isomerism is being shown (their names)

A
  • 3-methylbutan-1-ol

- pentan-3-ol

14
Q

what is the structural formula of 3-methylbutan-1-ol

A

CH2-CH2-CH-CH3
| |
OH CH3

15
Q

what is the structural formula of pentan-3-ol

A

CH3-CH2-CH-CH2-CH3
|
OH

16
Q

what does stereoisomerism refer to

A

two different ways to arrange atoms or groups of atoms

17
Q

what is different about stereoisomers

A
  • they have the same molecular and structural fromulae

- but have a different arrangement of atoms

18
Q

what is the structural formula of but-2-ene

A

CH3-CH=CH-CH3

19
Q

what is the first way you can arrange the atoms in but-2-ene

A
CH3 CH3
    |    |
   C=C      
    |    |
   H  H
20
Q

what is the second way you can arrange the atoms in but-2-ene

A
H CH3
    |    |
   C=C      
    |    |
CH3 H
21
Q

which isomer has the CH3 groups farthest away from each other and why

A
  • the second isomer
  • because they are across each other
  • as one is on top and the other is on the bottom
22
Q

what abbreviation would you add to the beginning of that isomers name to indicate this

A
  • trans

- which is latin for across

23
Q

what term would be used at the beginning of the first isomers name and why

A
  • 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
24
Q

what is this type of stereoisomeric relationship called

A
  • geometric isomers

- also known as cis-trans isomers

25
Q

why can stereoisomerism only exist in alkenes but not alkanes (specifically), what do alkenes have the alkanes dont)

A

because there needs to be s C=C bond for the cis and trans isomers to occur

26
Q

why does there need to be a C=C bond to stereoisomerism

A
  • 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
27
Q
is this a stereoisomer of but-2-ene and why
    H  CH3
     |    |
    C=C
     |    |
    H CH3
A
  • 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
28
Q

what is that compound then, compared to but-2-ene and what is its name

A
  • it is a structural isomer of but-2-ene

- and its name is methylpropene