I've learned that if you rotate a fischer projection by 180 degrees, then you get the exact same compound. If you rotate it by 90 degrees, you get it's enantiomer. Question 1: If you rotate it by 270 degrees, do you still get it's enantiomer? Question 2: Kaplan states that interchanging any pairs of substituents is the same as rotating it 180 degrees. For an example, Kaplan states that a fischer projection of Cl on top, CH3 on the bottom, H to the left and Br to the right is equal to another fischer projection of Br on top, H on the bottom, Cl to the right and CH3 to the left. I don't see how these two fischer projections are equal after interchanging the two pairs of substituents from the first fischer projection. If I were to rotate the first projection by 180 degrees, I would get Cl on the bottom, CH3 on top, H to the right and Br to the left. Then they would be equal. Is there another way to figure this?