This question is about isomers with the molecular formula C\_5H\_10O - AQA - A-Level Chemistry - Question 6 - 2021 - Paper 2

To distinguish between the two enantiomers of the branched chain aldehyde, you can use plane polarized light:

1. Pass plane polarized light through a sample of one enantiomer.
2. Measure the angle of rotation.
3. Repeat the process with the second enantiomer.
4. The two samples will rotate the plane of polarized light in opposite directions (one clockwise and the other counterclockwise).

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.

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.