How can I possibly escape?
Be honest! Look the other person in the eye and say, for example: “I’ve enjoyed talking to you (hopefully!). I must move on as there are a couple of other people I want to meet. May I have your card? (if you want to follow up). Is there anybody I could introduce you to?” Don’t promise what you won’t do, e.g. catching up with them later if you have no intention to do so.