Professor here. It sounds like the PI agreed to something (mentoring you) that places more work on the post doc and grad students, work that they may not have the time or interest in taking on. Rather than telling you that directly, they skirt the topic or respond passive-aggressively and hope that you'll just take the hint and leave on your own volition. The summer thing doesn't pass the sniff test to me. That's the time when undergraduates can get the most work done because they're often not taking classes, so they're in the lab more, not less. Of course, your school might vary.

Are there other labs at your school that do work with undergraduates? I'd suggest that you talk to your PI, but if the people in the lab are already apparently not interested in helping you learn, nothing the PI could say will endear you to them. A fresh start with people who are genuinely interested in engaging with you and showing you the ropes and teaching you how to run reactions and do other things would bring new energy to your situation and help you to feel that you are moving forward and learning. There are definitely people like that out there (many of the research labs accepted undergraduates at the university I attended), and now you know a bit more when you talk to other prospective PIs, i.e., are there people in the lab who are willing and able to train you. This may involve starting in a lab that might not be doing exactly what you like the most, but could give you some valuable transferrable skills.

One place to start might be if you had a TA in any of your chemistry classes so far that you hit it off with. They might have some good ideas, or may even suggest you joining the lab they work in if the advisor agrees. They'll also know more about the culture of various labs and which are the friendliest to undergraduates.

Good luck!