Contact the editor on the acceptance chances of my article I submitted a paper to a journal about two months ago and now the article has been under review for a month. It is my first article out for publication ever, so I am not the best at judging my chances of being accepted. However, I presented the paper on a conference and they offer the chance of entering it as a book chapter in a publication resulting from the conference. I now wonder if it would be ok to ask the editor of the journal if they can tell me some more on my chances of being accepted. Maybe they already got one review back and they can tell me what the verdict was there? Is this appropriate, and if so, should I explain truthfully why I ask this question to the editor?

PS: I would prefer the publication in the journal rather than the book chapter, but if I go for that option and it's not accepted I also can't be in the book because they need an answer now.
I doubt that you will be able to get any answer about the likelihood of acceptance from a good editor until all of the reviews are in.  As a editor, there are just too many ways that the last review might majorly change the view of a paper (e.g., negatively by pointing out that it is a cleverly disguised piece of plagiarism; positively by pointing out a value that all of the other reviewers have missed).  An editor who is acting professionally will thus never pre-judge the result before it is in hand.

You can always feel free to reach out and ask how long it's likely to be before you get an answer, but that's not something that can readily be relied upon either, given the frequent vagaries of reviewers.