(IUPAC Recommendations 1998)

Continue with Appendix 2

**Hydrocarbon parent components in order of decreasing seniority.**

1 | Polyphenylene | (C_{6})_{m} .C_{2m} | cf. 33 (m > 8) | (see FR-2.1.5) |

2 | Polynaphthylene | (C_{6})_{2k} .C_{2k} | cf. 25 (k > 4) | (see FR-2.1.6) |

3 | Polyacene | (C_{6})_{n} | cf. 39 (n > 10) | (see FR-2.1.2) |

4 | Polyaphene | (C_{6})_{n} | cf. 31 or 35 (n > 10) | (see FR-2.1.3) |

5 | Polyhelicene | (C_{6})_{n} | cf. 32 (n > 9) | (see FR-2.1.7) Note a |

6 | Nonaphenylene | (C_{6})_{9}.C_{18} | cf. 33 (m = 9) | (see FR-2.1.5) |

7 | ||||

8 | Decacene | (C_{6})_{10} | cf. 39 (n = 10) | (see FR-2.1.2) |

9 | Decaphene | (C_{6})_{10} | cf. 31 (n = 10) | (see FR-2.1.3) |

10 | Ovalene | (C_{6})_{10} | ||

11 | Decahelicene | (C_{6})_{10} | cf. 32 (n = 10) | (see FR-2.1.7) Note a |

12 | Octaphenylene | (C_{6})_{8}.C_{16} | cf. 33 (m = 8) | (see FR-2.1.5) |

13 | Tetranaphthylene | (C_{6})_{8}.C_{8} | cf. 25 (k = 4) | (see FR-2.1.6) |

14 | Nonacene | (C_{6})_{9} | cf. 39 (n = 9) | (see FR-2.1.2) |

15 | Nonaphene | (C_{6})_{9} | cf. 35 (n = 9) | (see FR-2.1.3) |

16 | Nonahelicene | (C_{6})_{9} | cf. 32 (n = 9) | (see FR-2.1.7) Note a |

17 | Heptaphenylene | (C_{6})_{7}.C_{14} | cf. 33 (m = 7) | (see FR-2.1.5) |

18 | Octacene | (C_{6})_{8} | cf. 39 (n = 8) | (see FR-2.1.2) |

19 | Octaphene | (C_{6})_{8} | cf. 31 (n = 8) | (see FR-2.1.3) |

20 | Pyranthrene | (C_{6})_{8} | ||

21 | Octahelicene | (C_{6})_{8} | cf. 32 (n = 8) | (see FR-2.1.7) Note a |

22 | Hexaphenylene | (C_{6})_{6}.C_{12} | cf. 33 (m = 6) | (see FR-2.1.5) |

23 | Heptacene | (C_{6})_{7} | cf. 39 (n = 7) | (see FR-2.1.2) |

24 | Heptaphene | (C_{6})_{7} | cf. 35 (n = 7) | (see FR-2.1.3) |

25 | Trinaphthylene | (C_{6})_{7} | (see FR-2.1.6) Three naphthalene | |

26 | Coronene | (C_{6})_{7} | ||

27 | Heptahelicene | (C_{6})_{7} | cf. 32 (n = 7) | (see FR-2.1.7) Note a |

28 | Rubicene | (C_{5})_{2}.(C_{6})_{5} | ||

29 | Pentaphenylene | (C_{6})_{5}.C_{10} | cf. 33 (m = 5) | (see FR-2.1.5) |

30 | Hexacene | (C_{6})_{6} | cf. 39 (n = 6) | (see FR-2.1.2) |

31 | Hexaphene | (C_{6})_{6} | (see FR-2.1.3) six rings hence | |

32 | Hexahelicene | (C_{6})_{6} | (see FR-2.1.7) Note asix rings hence | |

33 | Tetraphenylene | (C_{6})_{4}.C_{8} | (see FR-2.1.5) four benzene rings hence | |

34 | Pentacene | (C_{6})_{5} | cf. 39 (n = 5) | (see FR-2.1.2) |

35 | Pentaphene | (C_{6})_{5} | (see FR-2.1.3) five rings hence | |

36 | Perylene | (C_{6})_{5} | ||

37 | Picene | (C_{6})_{5} | ||

38 | Pleiadene | (C_{6})_{3}.C_{7} | ||

39 | Tetracene | (C_{6})_{4} | (see FR-2.1.2) Note bfour rings hence | |

40 | Tetraphene | (C_{6})_{4} | cf. 35 (n = 4) | (see FR-2.1.3) |

41 | Chrysene | (C_{6})_{4} | ||

42 | Pyrene | (C_{6})_{4} | ||

43 | Triphenylene | (C_{6})_{4} | ||

44 | Aceanthrylene | C_{5}.(C_{6})_{3} | ||

45 | Acephenanthrylene | C_{5}.(C_{6})3 | ||

46 | Fluoranthene | C_{5}.(C_{6})_{3} | ||

Note c | ||||

47 | Anthracene | (C_{6})_{3} | Note a | |

48 | Phenanthrene | (C_{6})_{3} | Note d | |

49 | Phenalene (1 H-form shown) | (C_{6})_{3} | ||

50 | Fluorene (9 H-form shown) | C_{5}.(C_{6})_{2} | ||

51 | Acenaphthylene | C_{5}.(C_{6})_{2} | ||

52 | Biphenylene | C_{4}.(C_{6})_{2} | Note e | |

53 | s-Indacene | (C_{5})_{2}.C_{6} | Note e | |

54 | as-Indacene | (C_{5})_{2}.C_{6} | Note e | |

55 | Polyalene | (Cn)_{2} (n > 6) | Heptalene (n = 7) shown(see FR-2.1.4) | |

56 | Azulene | C_{5}.C_{7} | ||

57 | Naphthalene | (C_{6})_{2} | ||

58 | Indene (1 H-form shown) | C_{5}.C_{6} | ||

59 | Pentalene | (C_{5})_{2} | (see FR-2.1.4) | |

60 | Polyalene | (Cp)_{2} | cf. 50 (p = 3 or 4) | (see FR-2.1.4) |

61 | [p]Annulene | C_{p} (p > 6) | Note f | |

62 | Benzene | C_{6} | ||

63 | [p]Annulene | C_{p} (p < 6) | Note g |

*Notes*

**a.** Non-standard numbering.

**b.** Formerly called naphthacene which is still used by *CAS* and *Beilstein*.

**c.** *CAS* and *Beilstein* includes trindene (cyclopenta[*e*]-*as*-indacene).

**d.** Non-standard orientation, hence non-standard numbering.

**e.** In the previous edition of these rules (rule A-21.1, ref 3) indacene was preferred to biphenylene. This is now reversed to follow FR-2.3.c (see also Table 20, ref 3a).

**f.** These names only apply for a parent component; otherwise cycloalka is used as a fusion prefix (see FR-2.1.1).

**g.** Only [5]annulene may be used as a parent *e.g.* cyclobuta[1,2:3,4]di[5]annulene. The prefix cycloalka- is used for attached components (see FR-2.1.1).

**3.** *IUPAC Nomenclature of Organic Chemistry, Sections A and B*, 1st edition, 1958; 2nd edition, 1966; 3rd edition (combined with section C), 1971; 4th edition (combined with sections C, D, E, F and H), 1979.

**3a.** *A Guide to IUPAC Nomenclature of Organic Compounds*,* Recommendations 1993*, Blackwell Scientific Publications, 1993.

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