[johngiml]

Hi,
Based on my attempt, I was able to rotate the ends of a Fischer projection, two alkyl branches.
However, I just need a firm confirmation for this.
Can I rotate the ends of a Fischer projection?
If so, are there any exceptions to it? or is that a general idea I can follow?
Would that violate the consistency of chirality?
Please, take a look at the following picture.
In my humble opinion, I think that if I rotate both ends of the first Fischer projection, I get a pair of enantiomers. However, I am afraid that I violate the chirality of this molecule.
Thank you.

[AWK]

Every even permutations of two substituent at the same carbon atom do not change configuration of this atom in Fischer projection.
Both your drawings have the same configuration at 2-C and 5-C of aldaric acids. But at 3-C and
4-C are different. The right one is D-glucaric acid. The left ...