How To Write The Iupac Name Of Alkanes . Yes (with the errata applied) 3. 3) grammar to be followed in writing the iupac name: Nomenclature of Alkanes — Organic Chemistry Tutor from www.organicchemistrytutor.com One c atom is at the front of the circle. If there is only one substituent on the parent chain, as in (a), number the parent chain from the end that gives the substituent the lowest possible number. These names are listed within the discussion of naming alkanes.