Configurational base unit

{
  "id": "MLC-T-CHM-002404",
  "term": "Configurational base unit",
  "field": "Chemistry",
  "definition": "A constitutional repeating unit of a regular polymer whose configuration is fixed at one or more stereogenic sites in the main chain, so it is one specific stereoisomer of the repeat unit. In isotactic polypropylene every base unit has the same configuration, R or S, at the methyl-bearing carbon, while in syndiotactic polypropylene R and S base units alternate. It differs from the configurational repeating unit, which is the smallest set of base units that repeats.",
  "subject": "Polymer",
  "see_also": [
    "chain",
    "constitutional repeating unit",
    "main chain",
    "regular block",
    "regular macromolecule",
    "regular oligomer molecule",
    "stereoisomerism"
  ],
  "references": [
    "PAC, 1996, 68, 2287. 'Glossary of basic terms in polymer science (IUPAC Recommendations 1996)' on page 2291 (https://doi.org/10.1351/pac199668122287)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/configurational-base-unit/"
}