It is actually built for that purpose! Or at least, there are many people dedicated to optimizing the use of Facebook at work, selling it into companies as an enterprise solution, and so on. There are millions of paying customers. At some point I believe it was called "Facebook for Work" but now it has been rebranded as "Workplace from Facebook".
Some features are work-specific, but it feels basically like you are using the Facebook interface, but just with all the content being from your coworkers about work stuff.
Easily one of the worst "productivity" tools I've ever been forced to use. Like facebook, it's optimized to bring your eyes to it, and not to make you productive.
Notifications are exactly like facebook notifications, so you'll get an email that says "open workplace to see this". To use the tool effectively, you need to have it open at all times. It's a weird in-between state of slack and email, where it's somewhat async and somewhat sync. You'll get overwhelmed with notifications and will want to have "inbox zero", which is considerably more difficult than in email, where you can optimize your workflow. The sidebar will have a list of groups you're in with read/notification counts that make absolutely no sense.
It also has chat functionality that can't be turned off, and it's not group based. It's like being forced to use gchat for all communications.
It has a "organization tree" feature that requires employees to fill in their own reporting structure. This also can't be turned off.
If you want your employees to spend all day chatting in forums inside of facebook, workplace is the product for you.
Some features are work-specific, but it feels basically like you are using the Facebook interface, but just with all the content being from your coworkers about work stuff.
https://www.workplace.com/