what are some quick rules of thumb in order to determine if a molecule is chiral/achiral?
1)check if it has an internal mirror plane. If it does it is definitely achiral. If it doesn't it can be either chiral or achiral.
- 2) check to see if it has chiral centers:
- -if it has one, it is chiral.
- -if it has more than one, it can be either chiral or achiral
- -if it has none, it is unlikely, but possible, for it to be chiral
3)if the molecule is planar, then it is achiral (be careful with this rule because some molecules that appear planar may actually not be planar)
4) If a molecule is sterically hindered such that there is no equilibrium between it's conformations, it is chiral
5) if an allene (a molecule that contains C=C=C) has two different groups attached to each end, it is chiral
6) if you are presented with a fischer projection or you can easily make a fischer projection of the molecule that you are trying to determine as either chiral or achiral, then make a mirror image of the fischer projection, rotate the mirror image 180 degrees, and see it lines up with the original molecule. If it doesn't your molecule is chiral
7) if the molecule that you are examining is a ring and it contains two heteroatoms that are anti- and opposite each other, the molecule is likely achiral.