Are homodesmotic reactions isodesmic reactions?

1 Answer
Dec 26, 2014

Yes, homodesmotic reactions are a subset of isodesmic reactions.

An isodesmic reaction is a reaction that has the same number and type of bonds in the reactants and in the products.

An example of an isodesmic reaction is

goldbook.iupac.org

Homodesmotic reactions are a subclass of isodesmic reactions.

Here, the reactants and products are even more similar. They must contain equal numbers of

  • atoms in the same state of hybridization
  • groups containing the same number of H atoms.

An example of a homodesmotic reaction is

chemistry.umeche.maine.edu

The reactants and products contain equal numbers of bonds between carbons in the same state of hybridization and hydrogens bound to identical atom types.

#C_(sp^3)"-"O_(sp^3) # = 1

#C_(sp^3)"-"C_(sp^2) # = 1

#C_(sp^2)"-"O_(sp^3) # = 1

#C_(sp^2)"-"C_(sp^2) # = 7

#C_(sp^2)"="C_(sp^2) # = 6

#C_(sp^3)H_3# = 2

#C_(sp^2)H_2 # = 2

#C_(sp^2)H # = 9