Synchronous

{
  "id": "MLC-T-CHM-011748",
  "term": "Synchronous",
  "field": "Chemistry",
  "definition": "A concerted process whose bond formation and bond rupture are equally advanced when the transition state is reached, so that neither lags behind the other. A concerted reaction can instead be asynchronous, with one bond change well ahead of the other, as in many Diels-Alder reactions of unsymmetrical partners. The cycloaddition of butadiene with ethylene is the textbook example, with both new sigma bonds forming to the same extent.",
  "subject": "Organic and Biomolecular Chemistry",
  "see_also": [
    "concerted process",
    "imbalance",
    "primitive change",
    "transition state"
  ],
  "references": [
    "PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1170 (https://doi.org/10.1351/pac199466051077)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/synchronous/"
}