When a tree dies from the top down it usually means that there is a root problem. It could be that there was root damaged when planting or there is some reason why that area is inhospitable to trees. Did the tree get watered well until the ground froze last year? If not, roots could have been killed and the tree is supporting only as many live branches as it can with its limited resources. If the tree had been there for a few years I would ask you to check for root girdling. That is when an improperly planted (too deep) tree has roots that circle around the trunk and choke it. 

I am not sure if this is your tree or the city's. If it is yours, you can wait until November and try to cut the branches back to live growth. That means branches where there is a green layer under the bark. Oaks should not be pruned April-October as they can get oak wilt, which is spread by beetles that are active in spring and summer. You can cut off dead branches now, but nothing live. So, for now, you could cut off the totally dead branches and cut back to the live growth in November. 

The branches coming out of the bottom should be removed in the fall. Another option is to remove them now and cover the cut area with latex paint. This is about the only time sealing tree wounds is recommended. But the lower branches are taking energy that the upper areas could use. You are not likely to get good form if you let one of these branches become the central leader of the tree. It is important to think of how the tree needs to look in 50 years when it is big and much harder to prune or remove.

But, the tree is struggling. You could let it go for the summer, maybe remove the lower growth and some of the dead upper growth, keep it well watered, fertilize it, and see what happens. Since you want this to be around for many years (and if it is your tree), I recommend replacing it. It is sometimes best to cut your losses and start with a healthy, well-formed tree. If you decide to try the acorns again, you could start them in pots or cover them with some hardware cloth until they germinate. But it is a slow process and you are delaying having a nice tree and a place for birds and squirrels to hang out. 

I agree with your passion for oaks. They aren't planted much any more because of oak wilt. It is tough to lose a new tree, but devastating to lose one that you have watched your kids grow up playing in. 

But you should try to find out why the trees keep dying. Water? Really bad soil? 

Good luck. Sorry there is no magic wand to fix this little guy's problems. If it was mine, I would replace it now. But it can be hard to give up on a tree. 

Thank you so much! We will have to think on this a bit and make a decision. Leaning toward replacement at this point, and then intense care and awareness.