Posting solutions to textbook problems online I'm interested in knowing whether there are any legal issues (e.g., copyright infringement) in posting solutions to problems of a (paid) textbook.

I have mentioned these problems in class and did not have the time to thoroughly solve them on the blackboard. I thought about typing up the solutions with an extended discussion on each problem and the concepts employed. However, before I do that, is there any legal action about which I should be concerned? More specifically, I'm thinking about typing them up in Jupyter Notebook-style and was planning on putting those up on a public Github repository.

I had initially typed up the problems as well, but decided to reference to the exercise number in the book, as the "wording" problem itself may be proprietary.

I'm aware that the book has a paid solutions manual to which I don't have access.
If you don't have the solutions book, and are thinking of putting your own solutions online, then there is no copyright concern because it is your own work. You probably shouldn't put the questions online with the answers, though. 
(disclaimer: IANAL.)