We don't have synonyms for quantivalence yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are quadrivalence and quantivalent.
(n) :
(chemistry, historical) Synonym of valence (“the combining capacity of an atom, functional group, or radical determined by the number of atoms of hydrogen with which it will unite, or the number of electrons that it will gain, lose, or share when it combines with other atoms, etc.”).
(n) :
(chemistry, historical) Synonym of valence (“the combining capacity of an atom, functional group, or radical determined by the number of atoms of hydrogen with which it will unite, or the number of electrons that it will gain, lose, or share when it combines with other atoms, etc.”).