Welcome, organic people!
Finally, I'm happy to announce that Laboratoire Organique is underway!
In this series I'm going to describe some of the experiments I'll do in my last lab course (before the graduation thesis). This lab is all about organic chemistry: we synthesize some drugs and perform some extraction of natural products.
Please, do not expect me to show you anything complicated or new: I guess most of the stuff here will look very simple to serious organic people, but, nevertheless, I thought it'd have been nice to say goodbye to organic chemistry, posting what industrial pharmacists have to know, at least.
Still, this will never be Organic Prep Daily. Maybe it's an introduction to it.
For the first "episode", I've chosen an old friend: Nifedipine.
So, last Friday we began the one-pot synthesis of this drug, putting the reagent in 10 mL of isopropanol and heating under reflux throughout the week-end.
The mechanism is pretty simple: a common Hantzsch synthesis. This means you solely need to yield an enamine and a Knoevenagel adduct.
Interestingly, this is achieved with three reagents, only: methylamino crotonate (0.5844g), methylacetoacetate (0.54mL) and 2-nitrobenzaldehyde (0.7706g).
So, while I was preparing myself for my structural biology exam, the reaction occurred.
Some drops of the yellow oil found in the round-bottom flask were used for assaying whether the reaction actually had taken place or not, with a TLC.
Then, the isopropanol was evaporated and I placed the flask in a water bath and tried to crystallize nifedipine through trituration. As precipitating solvent we had chosen n-hexane (3mL), sticking to literature, I believe.
Unfortunately, instead of a powder, a disgusting gel-like substance appeared: this required, predictably, the addition of some ethyl acetate (and, once again, some hexane).
Then, I used a Hirsch funnel for the final suction filtration of the crystals.
A TLC (mobile phase: hexane-ethyl acetate 1.5:1) confirmed my colleague and I had worked well, since the product was almost completely pure.
The yield was a not-so-exciting 43% (0.7452g), but the melting point was 169°C (expected 171-175°C) and the IR spectrum matched perfectly the one obtained with a standard solution.
Oh, and we are not allowed to play with the NMR...that's stuff for serious organic chemists, I guess.
No NMR's? I hope that was sarcastic and not half-decent or half-ass.
We don't get the NMR spectrum of anything we synthetize in the lab. First, because it's just a lab course, where, as you can see, we do simple stuff.
Then, we are approximately a hundred people and there is only one machine in the department: imagine the queue.
Only Phd students or those who are working on their graduation thesis use it.