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Photochemical Electrocyclic Reactions definitions

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  • Photochemical Electrocyclic Reaction
    An intramolecular pericyclic process where light triggers the conversion of a pi bond into a sigma bond, forming a ring.
  • Pericyclic Reaction
    A concerted reaction involving cyclic redistribution of bonding electrons, often leading to ring formation.
  • Intramolecular Reaction
    A transformation occurring within a single molecule, resulting in bond reorganization without external reactants.
  • Conjugated Polyene
    A molecule with alternating double and single bonds, capable of undergoing light-induced ring closure.
  • Frontier Molecular Orbital Theory
    A model focusing on the highest occupied and lowest unoccupied orbitals to predict reaction outcomes and stereochemistry.
  • HOMO
    The highest energy molecular orbital containing electrons, crucial for determining reaction stereochemistry after light excitation.
  • LUMO
    The lowest energy molecular orbital without electrons, whose identity shifts upon light absorption but is less relevant here.
  • Ground State
    The lowest energy electronic configuration of a molecule before light absorption alters electron distribution.
  • Excited State
    A higher energy electronic configuration achieved when electrons absorb light and move to antibonding orbitals.
  • Bonding Orbital
    A molecular orbital where electron density is concentrated between nuclei, stabilizing the molecule.
  • Antibonding Orbital
    A molecular orbital with a node between nuclei, destabilizing the molecule when occupied by electrons.
  • Sigma Bond
    A single covalent bond formed by direct orbital overlap, created during the ring closure in these reactions.
  • Pi Bond
    A covalent bond formed by sideways overlap of p orbitals, one of which is lost during the photochemical process.
  • Node
    A region in a molecular orbital where the probability of finding an electron is zero, increasing with orbital energy.
  • Stereochemistry
    The spatial arrangement of atoms in a molecule, determined by the symmetry of the HOMO after light activation.