## Group Contributions to ΔHf

°(g) and

*S*°(g) at 298 K*Group | ΔH° (kJ/mol)_{f} | S° (J/mol K) |
---|---|---|

C-(H)_{3}(C) | -42.1 | 127.1 |

C-(H)_{2}(C)_{2} | -20.7 | 39.4 |

C-(H)(C)_{3} | -7.9 | -50.4 |

C-(C)_{4} | 2.1 | -146.7 |

C_{d}-(H)_{2} | 26.2 | 115.4 |

C_{d}-(H)(C) | 35.9 | 33.3 |

C_{d}-(C)_{2} | 43.2 | -53.1 |

C_{d}-(C_{d})(H) | 28.3 | 26.7 |

C_{d}-(C_{d})(C) | 37.1 | -61.0 |

[C_{d}-(C_{B})(H)] | 28.3 | 26.8 |

C_{d}-(C_{B})(C) | 36.1 | -61.0 |

Group | ΔH° (kJ/mol)_{f} | S° (J/mol K) |
---|---|---|

[C_{d}-(C_{t})(H)] | 28.3 | 26.8 |

C-(C_{d})(C)(H)_{2} | -19.9 | 41.0 |

C-(C_{d})_{2}(H)_{2} | -17.9 | 42.6 |

C-(C_{d})(C)_{3} | 7.0 | -145.1 |

C_{a} | 143.0 | 25.1 |

C-(C_{d})(C)_{2}(H) | -6.2 | -48.9 |

C-(C_{d})(C_{B})(H)_{2} | -17.9 | 42.6 |

C-(C_{B})(C)_{2}(H) | -4.1 | -51.0 |

C-(C_{B})(C)(H)_{2} | -20.3 | 38.9 |

C-(C_{B})(C)_{3} | 11.8 | -147.0 |

C_{B}-(H) | 13.8 | 48.2 |

Group | ΔH° (kJ/mol)_{f} | S° (J/mol K) |
---|---|---|

C_{B}-(C) | 23.0 | -32.1 |

C_{B}-(C_{d}) | 23.7 | -32.6 |

[C_{B}-(C_{t})] | 23.8 | -32.6 |

C_{B}-(C_{B}) | 20.7 | -36.1 |

C-(C_{t})(C)_{2}(H) | -7.2 | -46.8 |

C-(C_{t})(C)(H)_{2} | -19.8 | 43.0 |

C_{t}-(C) | 115.2 | 26.5 |

C_{t}-(H) | 112.6 | 103.2 |

C_{t}-(C_{d}) | 122.1 | 26.9 |

C_{t}-(C_{B}) | 122.1 | 26.9 |

*The subscripts "d" and "t" designate carbon atoms in carbon-carbon double and triple bonds; "a", an allenic carbon; "B", an aromatic carbon; "A", a nitrogen atom in a nitrogen-nitrogen double bond; and "I", a nitrogen atom in a nitrogen-carbon double bond. Bracketed values are estimated.

Reference: S.W. Benson, F.R. Cruickshank, D.M. Golden, G.R. Haugen, H.E. O'Neal, A.S. Rodgers, R. Shaw, and R. Walsh, Chem. Rev., 69, 279 (1969).