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R and S Configuration definitions

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  • Chiral Center
    An atom bonded to four distinct groups, creating non-superimposable mirror images and enabling stereoisomerism.
  • Stereoisomer
    A molecule with the same connectivity as another but differing in spatial arrangement due to chiral centers.
  • IUPAC Naming System
    A standardized protocol for assigning unique, systematic names to chemical compounds, including stereochemistry.
  • Cahn-Ingold-Prelog Nomenclature
    A priority-based system for designating the absolute configuration of chiral centers using atomic numbers.
  • Atomic Mass
    A value from the periodic table used to rank atoms attached to a chiral center for priority assignment.
  • Priority Assignment
    The process of ranking groups attached to a chiral center based on atomic mass and connectivity.
  • Playoff System
    A tie-breaking method comparing the next set of atoms when two groups have identical atomic masses.
  • Double Bond Rule
    A guideline where double bonds are counted as two connections when determining group priorities.
  • Triple Bond Rule
    A guideline where triple bonds are counted as three connections for priority determination.
  • Dash Representation
    A notation in 3D structures indicating a group is oriented away from the viewer, behind the plane.
  • Clockwise Rotation
    A tracing direction from highest to lowest priority that results in an R configuration if the lowest group is in back.
  • Counterclockwise Rotation
    A tracing direction from highest to lowest priority that results in an S configuration if the lowest group is in back.
  • R Configuration
    A designation for a chiral center when the path from highest to lowest priority follows a clockwise direction.
  • S Configuration
    A designation for a chiral center when the path from highest to lowest priority follows a counterclockwise direction.
  • Group Swap Adjustment
    A correction step where the R/S assignment is reversed if the lowest priority group is not in the back.