Hello fellow chemists!
I have few questions about my reaction please help me!
So I have been doing a very simple debromination reaction of 5-bromo-2,3-diamino pyridine using Zinc, NH4Cl and methanol. I am facing problems during work up of this reaction (500grams scale).
After the reaction is complete I have filtered zinc etc on celite and the MLR is being basified using 50% NaOH to free the HBr salts if pyridine. Solid separates out ( my assumption is I am getting NaBr). This solid is again filtered out and the MLR is being distilled out. After the distillation is completed I am ending up with lots of inorganic material along with my compound.
1) What am I doing wrong?
2) Is basifying of the MLR necessary?
3) I have a doubt about the compound forming pyridinium salt. Won't the Bromine liberated form Zinc Bromide (I am using excess Zinc)
4) Can any other base be used for basifying? (if basification is required)
Please help me!
1. I am wondering if making the reaction mixture basic by NaOH is really necessary. When you add the NaOH solution, solid came out only because of addition of water to force our organic stuff, but this is my guess only, as you did not state how much stuff came out. But I expect there won't be too much precipitate, given your diamino compound should be pretty hydrophilic.
2. My understanding is that the debromination gives ZnBr2, and I do not think there should be any acid generated (and hence no need to add base). The only acid is what you added: NH4Cl, but it is very weak.
3. Of course you will have a lot of inorganic stuff after distilling your MLR (mother liqour? just to make sure, never heard of this abbreviation). Your MLR is basically methanol and lots of water.