# Hydrolysis of Magnesium Carbide

I came across a question in which the following reaction was taking place:

$$\ce{Mg4C3 + H2O -> CH3CH \bond{#} CH}$$

Each $$\ce{Mg}$$ atom must be present in a +2 oxidation state, thus the total charge of the cation is +8. We thus have a $$\ce{C3^{8-}}$$ anion. The only structure of this $$\ce{C3^{8-}}$$ anion I could come up with was three carbons attached to each other in a linear fashion, with the terminal carbons each bearing a -3 charge and the central carbon bearing a -2 charge.

From this anion I would have assumed that the product formed upon hydrolysis is propane, but the product formed in the above reaction is propyne, just like when $$\ce{Mg2C3}$$ undergoes hydrolysis.

I'm guessing that the explanation for propyne being formed is the actual lattice structure of $$\ce{Mg4C3}$$, but I couldn't find any literature referencing this reaction or the structure of $$\ce{Mg4C3}$$.

The question is taken from:

• V.K. Jaiswal, s-block elements, Problems in Inorganic Chemistry, Thirteenth Edition, Page 331, question 36
• @Poutnik agreed, but if the 3 carbon atoms don't form a single anion, how will we get a product which consists of 3 interconnected carbon atoms? – Ashish Ahuja Nov 12 at 18:08
• I have just quoted Wikipedia, I have not claimed anything. Note Mg2C3, not Mg4C3. – Poutnik Nov 12 at 18:23
• Typo? Should it be Mg2C3? – Waylander Nov 12 at 18:41
• Yeah, seems a blatant mistake. – Mithoron Nov 12 at 18:46
• I don’t know if this is enough to prove that this is not a typo but this paper mentions Mg4C3 – Robin Singh Nov 13 at 3:34