Having had the chance recently to see a number of interview seminars (other than my own, for once!), I have a few more thoughts for aspiring job seekers. It turns out that many of these are things that high school speech teachers have been telling their students for decades, but you know, there's only so much new information in this world.
Know your audience. In this case, your audience is pretty well-informed about synthetic chemistry, since they've been putting food on the table by practicing it. To pick one example, there's no point in stepping through detailed reaction mechanism slides for reactions that people already know. A surprising number of people seem to do this, perhaps thinking that it'll demonstrate that they know their stuff, but it tends to have the opposite effect. If you want to put one of these up, don't leave it up there for long. Just hit the highlights (you know, like you're familiar with it) and keep going. And that brings up another key point. . .
Keep moving. I'm not saying that you should fly through your slides, although I've never in my life seen a job candidate who did. I'm saying that you shouldn't linger on them. Figure out what you're trying to say with each slide, say it, and move on. Not to be too cynical about it, but the longer your slide sits up there, the greater the chances of bad things happening: either you say something unhelpful because you feel you should be saying something, or people start fiinding the mistakes in your slide, or people start looking out the window. You don't want any of these. I can't count the number of times I've watched a job candidate while silently imploring them to hit a button and go to the next slide already. It's easier to keep moving if you remember that. . .
Your slides should tell a story. Maybe you have two stories, or even three, if you've had to break things up and talk about more than one project. That's OK. But what you should never, ever do is put up a bunch of unrelated stuff in no particular order. Once in a while I've seen this kind of talk, but I have never, ever seen one lead to a job offer.
Don't ask for questions until the end. This may also sound a bit cynical, but trust me on it. At many companies, they'll interrupt you if they really want to ask questions; you don't have to invite them. If the culture is to wait until the end, then it's in your best interest to go along with that. I say these because many people sink their chances by the way they handle questions from the audience. You want to have some questions, of course (no questions at all is a bad sign), but you want them to be the ones you're prepared for. Give people those good answers you've worked up and move on. The more opportunities you give people to grill you, the better the chances of them finding gaps in your knowledge. But that said. . .
Don't be afraid to say "I don't know" (or its equivalent). Some of those equivalents are "You know, we wanted to investigate that, but weren't able do during the project" or "That's a good question, and we'd like to know the answer to that one, too". Now, you don't want to use these when someone asks you why you used lithium aluminum hydride or something - those are the kinds of questions you have to be ready for. But if someone asks you a question that you really, really don't know the answer to, punt. It's better than trying to whip something up on the spot. But remember. . .
Put your work in context. It's very important that you show that you know why you were doing something, and how it fit into the larger scheme. You're always going to be working inside a larger context if you're in industry, since chemistry is just a means to an end. A classic interview-killer is to say that you did something because that's what someone told you to do. If you don't have some broader reasons than that - or if it's never occurred to you that you might need some - your chances of being hired at a drug company are very slim. And finally. . .
Remember what your talk is supposed to do. Many of the points above boil down to this one. You are not giving an informational talk, you're giving a persuasive one, but a shocking number of candidates don't seem to realize this. As mentioned above, you may not be able to tell your drug-company audience much that they don't already know. But you can persuade them that you know the stuff well, that you did a good job with it, and can do the same for them. Everything you're presenting should be aimed at demonstrating those points.