Question

What is the Fisher projection of `\text{(s)}-3-\text{bromo}-3-\text{chlorohexane}`?

Answer 1

Here's what I get.

Explanation:

The structure of 3−bromo−3−chlorohexane is

To get the 3D structure, I arbitrarily drew the wedge and dash as above (I had
a 50 % chance of getting it right).

If it turns out to be wrong, I will interchange `"Br"` and `"Cl"`.

To get the Fischer projection, we draw the carbon backbone vertically with `"C1"` at the top.

Remember that the horizontal bonds must each be wedges.

We assign priorities as follows:

`"Br = 1, Cl = 2, C4 = 3, C2 = 4"`

Luckily, the lowest-priority group (`"C2"`) is behind the screen.

The `"1 → 2 → 3"` direction is counterclockwise, so this is the Fischer projection of (S)-3−bromo−3−chlorohexane.

Note: you could also use condensed structural formulas for the groups above and below `"C3"`, as in the structure below.