# What are states of hybridization in homodesmotic reactions?

Dec 26, 2014

States of hybridization in a homodesmotic reaction refer to whether the bonds are sp³, sp², or $s p$ hybridized.

The products and reactants in homodesmotic reactions must also have equal numbers of each type of carbon-carbon bond: ${C}_{s {p}^{3}} \text{-} {C}_{s {p}^{3}}$, ${C}_{s {p}^{3}} \text{-} {C}_{s {p}^{2}}$, ${C}_{s {p}^{3}} \text{-} {C}_{s p}$, ${C}_{s {p}^{2}} \text{-} {C}_{s {p}^{2}}$,${C}_{s {p}^{2}} \text{-} {C}_{s p}$, ${C}_{s p} \text{-} {C}_{s p}$, ${C}_{s {p}^{2}} \text{=} {C}_{s {p}^{2}}$, ${C}_{s {p}^{2}} \text{=} {C}_{s p}$, ${C}_{s p} \text{≡} {C}_{s p}$.

An example illustrating this definition is the reaction

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

${C}_{s {p}^{3}} \text{-} {C}_{s {p}^{2}}$ = 1

${C}_{s {p}^{2}} \text{-} {C}_{s {p}^{2}}$ = 1

${C}_{s {p}^{2}} \text{-} {C}_{s p}$ = 1

${C}_{s {p}^{2}} \text{=} {C}_{s {p}^{2}}$ = 3

${C}_{s p} \text{≡} {C}_{s p}$ = 1

${C}_{s {p}^{3}} {H}_{3}$ = 1

${C}_{s {p}^{2}} {H}_{2}$ = 3

${C}_{s {p}^{2}} H$ = 2

${C}_{s p} H$ = 1