Final answer:
The Fischer projections for (2R,3R)-2,3-dibromobutane and (2S,3S)-2,3-dibromobutane are drawn by using a vertical line for the butane chain, placing bromine atoms on the horizontal lines as dictated by the R or S configurations, and completing the structure with hydrogen atoms.
Step-by-step explanation:
The Fischer projection is a method used to represent three-dimensional molecules in two dimensions, primarily used for molecules with chiral centers. The Fischer projection for (2R,3R)-2,3-dibromobutane and (2S,3S)-2,3-dibromobutane can be drawn by first identifying the chiral centers and their configurations. Remember that in a Fischer projection, the vertical lines denote bonds going away from the viewer, while horizontal lines denote bonds coming towards the viewer.
For (2R,3R)-2,3-dibromobutane:
- Draw a vertical line to represent the butane backbone.
- Place the second carbon from the top and third carbon each with a bromine (Br) atom on the horizontal line, signifying that these groups are coming towards the viewer.
- Since both chiral centers are R, the Br atoms will be on opposite sides: the Br on C2 will be on the left and the Br on C3 will be on the right.
- Fill the other two bonds of the chiral centers with hydrogen atoms (H), placed on the horizontal line opposite the Br atoms.
For (2S,3S)-2,3-dibromobutane:
- Draw a vertical line to represent the butane backbone.
- Place the second carbon from the top and third carbon each with a bromine (Br) atom on the horizontal line.
- This time, since both chiral centers are S, the Br atoms will be on the same side: both Br atoms will be on the left.
- Complete the structure by adding the H atoms on the horizontal line opposite the Br atoms.
These projections show the configuration of the chiral centers clearly and allow for easy comparison between enantiomers.