Predict the product of the following reaction and propose

Step 1 of 4

Reaction of a benzene derivative with sodium metal and ammonia in an alcohol solvent is called a Birch reduction, and it leads to a cyclohexa-1,4-diene derivative.

Mechanism:

As a Group I metal, sodium has one available electron in its valence shell. This electron attacks the tetramethylbenzene starting material, causing the ring's \(\pi\) electrons to rearrange so that the negative charge doesn’t reside on a methylated carbon. Recall that methyl carbons are electron donating via hyperconjugation and so having the negative charge reside on a methylated ring carbon would be less stable than the indicated arrangement. This intermediate also contains a radical, making it a radical anion.