text: As stated above, BGIT can be used to calculate heats of formation, which are important in understanding the strengths of bonds and entire molecules. Furthermore, the method can be used to quickly estimate whether a reaction is endothermic or exothermic.  These values are for gas-phase thermodynamics and typically at 298 K.  Benson and coworkers have continued collecting data since their 1958 publication and have since published even more group increments, including strained rings, radicals, halogens, and more.  Even though BGIT was introduced in 1958 and would seem to be antiquated in the modern age of advanced computing, the theory still finds practical applications.  In a 2006 article, Gronert states: "Aside from molecular mechanics computer packages, the best known additivity scheme is Benson's."  Fishtik and Datta also give credit to BGIT: "Despite their empirical character, GA methods continue to remain a powerful and relatively accurate technique for the estimation of thermodynamic properties of the chemical species, even in the era of supercomputers"
  When calculating the heat of formation, all the atoms in the molecule must be accounted for (hydrogen atoms are not included as specific groups).  The figure above displays a simple application for predicting the standard enthalpy of isobutylbenzene. First, it is usually very helpful to start by numbering the atoms.  It is much easier then to list the specific groups along with the corresponding number from the table.  Each individual atom is accounted for, where C−(H) accounts for one benzene carbon bound to a hydrogen atom. This would be multiplied by five, since there are five C−(H) atoms. The C−(C) molecule further accounts for the other benzene carbon attached to the butyl group. The C−(C)(C)(H)2 accounts for the carbon linked to the benzene group on the butyl moiety. The 2 carbon of the butyl group would be C−(C)(H) because it is a tertiary carbon (connecting to three other carbon atoms). The final calculation comes from the CH groups connected to the 2 carbon; C−(C)(H). The total calculations add to −5.15 kcal/mol (−21.6 kJ/mol), which is identical to the experimental value, which can be found in the National Institute of Standards and Technology Chemistry WebBook 
  Another example from the literature is when the BGIT was used to corroborate experimental evidence of the enthalpy of formation of benzo[k]fluoranthene.  The experimental value was determined to be 296.6 kJ/mol with a standard deviation of 6.4 kJ/mol.  This is within the error of the BGIT and is in good agreement with the calculated value.  Notice that the carbons at the fused rings are treated differently than regular benzene carbons.  Not only can the BGIT be used to confirm experimental values, but can also to confirm theoretical values.
  BGIT also can be used for comparing the thermodynamics of simplified hydrogenation reactions for alkene (2-methyl-1-butene) and ketone(2-butanone).  This is a thermodynamic argument, and kinetics are ignored.  As determined by the enthalpies below the corresponding molecules, the enthalpy of reaction for 2-methyl-1-butene going to 2-methyl-butane is −29.07 kcal/mol, which is in great agreement with the value calculated from NIST, −28.31 kcal/mol.  For 2-butanone going to 2-butanol, enthalpy of reaction is −13.75 kcal/mol, which again is in excellent agreement with −14.02 kcal/mol.  While both reactions are thermodynamically favored, the alkene will be far more exothermic than the corresponding ketone.