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This question is about isomers with the molecular formula C\_5H\_10O - AQA - A-Level Chemistry - Question 6 - 2021 - Paper 2
Question 6
This question is about isomers with the molecular formula C\_5H\_10O. 6.1 Draw the skeletal formula of a branched chain aldehyde with molecular formula C\_5H\_10O t... show full transcript
Worked Solution & Example Answer:This question is about isomers with the molecular formula C\_5H\_10O - AQA - A-Level Chemistry - Question 6 - 2021 - Paper 2
Step 1
6.1 Draw the skeletal formula of a branched chain aldehyde with molecular formula C\_5H\_10O that is optically active.
Answer
The skeletal formula for an optically active branched chain aldehyde C_5H_10O is:
CHO
|
CH3-CH-CH2-CH3
|
CH3
This structure has a chiral carbon atom that allows for optical activity.
Step 2
6.2 Describe how you distinguish between separate samples of the two enantiomers of the branched chain aldehyde C\_5H\_10O.
Answer
To distinguish between the two enantiomers of the branched chain aldehyde, you can use plane polarized light:
- Pass plane polarized light through a sample of one enantiomer.
- Measure the angle of rotation.
- Repeat the process with the second enantiomer.
- The two samples will rotate the plane of polarized light in opposite directions (one clockwise and the other counterclockwise).
Step 3
6.3 Draw the E and Z forms of a structural isomer of C\_5H\_10O that shows both optical and geometric isomerism.
Answer
The E and Z forms of the structural isomer can be represented as follows:
E isomer:
CH3 CHO
| |
CH3-C=C-CH2-CH3
| |
OH CH3
Z isomer:
CH3 CHO
| |
CH3-C=C-CH2-CH3
| |
OH CH3
In these structures, you can see the spatial arrangements of the substituents around the double bond, which determines whether it is the E or Z isomer.
Step 4
6.4 Draw two other cyclic isomers of C\_5H\_10O that have an ether functional group and only three peaks in their 13C NMR spectra.
Answer
Two cyclic isomers of C_5H_10O with an ether functional group are:
Isomer 1:
C1 O
|
C2-C3
|
C4
Isomer 2:
C1 O
|
C2-C3-C4
|
C5
These cyclic structures will exhibit only three peaks in their 13C NMR spectra due to their symmetric nature.