when assigning configurations on Fischer projections what must you always do?
invert the configuration you get
When assigning configurations on Fischer projections, you must always prioritize the substituents attached to the chiral center. To do this, assign priorities based on the atomic number of the atoms directly attached to the chiral center. The higher the atomic number, the higher the priority. If two or more substituents have the same atom attached to the chiral center, compare the atoms attached to these substituents until a difference is found. Once priorities have been assigned, the Fischer projection can be oriented in a specific way to determine its configuration. Specifically, if the lowest-priority substituent is pointing towards the back, the configuration is “R”, and if it is pointing towards the front, the configuration is “S”. It is important to apply this rule consistently in order to accurately assign configurations on Fischer projections.
More Answers:
Geometry of Molecules with 2 Electron Domains: Linear vs. Bent Shapes and Bond AnglesEnantiomers: Importance in Drug Development and Manufacturing
Key Importance of Chiral Carbon in Chemistry, Biochemistry, and Pharmaceuticals