I don't think that it would be to hard to mock up one, the class abilities for 4th are pretty universal... But just play pathfinder
Any character with the Alchemist feat can make potions, and other nasty stuff.
It's detailed in Adventurer's Vault, along with all the stuff they can make.
Or the Artificer from the Eberron Player's Guide.
Certainly the Alchemists feat is a good base for a class that has a whole bunch of nifty gear up his sleeve.
There is a big caveat however. All that stuff costs gold and potentially quite a bit of it really. The real catch is that its a viable option if you have 4 or fewer fellow adventurers and pretty much off the table if you have six or more fellow adventurers.
Its odd but the size of the adventuring group really dictates how much of this sort of thing you can use. The reason for that comes down to the treasure distribution system used in 4E. If you look closely at it you'll note that while the number of magic items the DM is giving out changes based on the number of players the amount of gold is static. That static amount of gold goes a lot further divided by four fellow adventurers then it does divided by eight fellow adventurers.
I suspect that there is method to this madness. I play in a 6 player campaign and run a 4 player campaign and more players is straight up more powerful. There are more ways to synergize and synergy is what 4E is all about so having more players is more powerful even if the DM is following the guidelines and adjusting the number of monsters. Thus, I suspect, the wealth by level system helps even things out. In my 6 player game we are poor as church mice and consumable gear really just is not much of an option except in a last resort type situation.
In my 4 player campaign my players are loaded down with coin and they buy a fair number of consumables in part because they really need the gear to help get them out of the jams they so often find themselves in.
All that said if you are in the type of game where you can afford this stuff its a whole lot of fun. The stuff tends to come with its own to hit rating etc. so you can generally build very well around it by making some one that has a lot of good stats but is not min-maxed in just one area and then use glue bombs and and crossbow launched flashbangs to fight your battles.
Finally, as a side note, if you have a larger group and your the DM you can get more of this sort of thing. I informed the players in the larger game that when my turn to DM comes up again we'd be using more of a random treasure system but I'd give them loot as if they where a level higher. The result should be that they are getting less optimized magical gear and selling more stuff as useless but there should also be a lot more coin floating around. The combination of less ability to acquire truly optimized permanent magical gear and larger then normal quantities of gold should result in players depending more on the alchemical gear. Especially if the DM is using the new rarity magic system since you can buy alchemical gear without hindrance while only the most plain permanent magical gear is available.
What Fabes said, Eberron's Artificer is the closest to an Alchemist.
Alternatively, if you want a character that works similar in concept to the bomb-tossing, mutagen-drinking Alchemist class, you could reflavor the Druid into something like an Alchemist quite easily. (This assumes your DM is fine with you doing that, of course.) For the powers you can use in human form, just make them quick alchemical concoctions instead of primal magic. (Let's say they expire a few seconds after you mix them, just to explain why you can't just hand them off to someone else.) Instead of Wild Shape turning you into an animal, you just drink a potion, turn into Mr Hyde and start beating things with your staff. Then just switch Ritual Caster with Alchemy because an alchemist without Alchemy is silly and you should be good to go.
Of course, if you don't want to reflavor a class too much, or you don't care that much about it playing like the Alchemist class, just play an Artificer and take Master Mixer as one of your feats. It's the closest to what you want otherwise.