The aqueous hydroxide-promoted reaction of the compound with 2,2-dimethylpropanal (pivalaldehyde) at elevated temperature gives only one product. Write the mechanism of the reaction and the structure of the final product. Would you mix hydroxide with the ketone and then add the aldehyde, or would you mix hydroxide with the aldehyde and then add the ketone?

  The mechanism of this reaction i shown on the second uploaded image

The final product of the reaction is shown on the third uploaded image

The hydroxide would be first mixed with the ketone group before the aldehyde is added  

Explanation:

The compound given in the question is 2,2-dimethylpropanal (pivalaldehyde) the structural formula is shown on the first uploaded image

looking at the structurally formula we can see that the hydroxide promoted reaction of this compound would be between the ketone and aldehyde functional group present in this compound in the presence of a hydroxide

Now this process of the reaction is this

    The is first  made to react with the ketone group

     Then the aldehyde is added

     What happens is that that the would search for an acidic proton because it is a base and this acidic proton is present in ketone and absent in aldehyde group hence the reason for the first reaction with the ketone group before the aldehyde is added