fireoncells

Hello ! I am doing some research on thiazole chemistry. I have to brominate 1-(2-(pyridin-4-yl)thiazol-5-yl)ethanone to obtain the corresponding bromoketone. I've tried this with elemental bromine in CCl4 (stirring, r.t) and obtained a red powder after vacuum filtration . The problem is that this molecule has to 2 aromatic N atoms and the bromine is actually incorporated into the molecule (probably like in pyridinium tribromide?). The 1HNMR spectra shows that there has no bromination occured. I have tried to brominate it with NBS/CCl4 + 2 drops HCl conc under reflux. TLC shows that the bromination is incomplete. I don't like CCl4 at all-it is toxic and it doesn't work so I have to try some other system like NBS/MeCN or NBS/DMF with an appropriate catalyst. One of them is HBr but I don't have HBr so I have to make it. TsOH might also be a very good idea but the problem is that can form salt with my haloketone complicating isolation. So my questions are: Which is the best method to brominate this molecule with pronounced basicity ? (no Br2 please ! ) ) and how to isolate the product (in base form not pyridinum salt) ? I really need the oppinion of an expert....

Periodinane, you really have to understand that I try to work scientifically because I am not a technician okay? I have access to sciencedirect and I do consult a lot of articles. I don't know how to use your SciFinder. I am sure that it doesn't tell me how to brominate my specific ketone. This is a science forum where I ask for opinions not for links. Sorry if I was a bit rude with you...as this is an internet forum it is impossible to clarify immediately any misconceptions. However everything was very clear. I told you how the reaction proceeds with elemental bromine. Yes, I did isolate product and made lots of analysis. There is no doubt that is a pyridinium tribromide. My Q was how to brominate with NBS ! I did not asked you to tell me the reaction product with bromine. As you are just a student, please don't post here anymore. I really don't need your opinion okay? This topic is closed for you. Thank you. Hello. Any organic chemist with experience in this field ? I try to figure out how to brominate my ketone with NBS. I'll go to the lab next week to research new methodology but I'll wait for comments and suggestions. Thank you all !

Sorry.. I didn't attack anyone. The only thing I want is a professional answer to my question. My question is stated very clearly. It also very clear what the product is so we shouldn't argue about that. How can I brominate and isolate using NBS ? I am new in this field so please help me. I didn't want to be mean but come on ! I am becoming frustrated not because I dont get any help, but because I receive some stupid answers from somebody who clearly doesn't know basic chemistry. And (s)he also states is a PhD organic chemist. COME ON !

You are anything but a chemist (no offense meant) as long as you state CCl4 is polar. Also, it does NOTHING to do with any reaction with CCl4. In the first step there is a little bromination which forms HBr. HBr + Py...+ Br2 ---> Br3 - +HNPy...Now the reaction stops. Any bromoketone formed is removed perhaps during purification. The Py and Th rings are strongly electron deficient so it will not react AT ALL. Reaction of Py with Br2 has very low yield as far as I know. Anyway, thank you for your oppinion

Why do you doubt it is reacting with the Py N ?? It is very clear that it does react. Are you an organic chemist? In CCl4 you form a ionic compound which leaves the system...simple.

You really don't understand do you? I have a particular problem with this molecule, Br2 is excluded ! I cannot brominate with Br2 because it reacts on a different manner with the Py N...

Hello ! I am doing some research on thiazole chemistry. I have to brominate 1-(2-(pyridin-4-yl)thiazol-5-yl)ethanone to obtain the corresponding bromoketone. I've tried this with elemental bromine in CCl4 (stirring, r.t) and obtained a red powder after vacuum filtration . The problem is that this molecule has to 2 aromatic N atoms and the bromine is actually incorporated into the molecule (probably like in pyridinium tribromide?). The 1HNMR spectra shows that there has no bromination occured. I have tried to brominate it with NBS/CCl4 + 2 drops HCl conc under reflux. TLC shows that the bromination is incomplete. I don't like CCl4 at all-it is toxic and it doesn't work so I have to try some other system like NBS/MeCN or NBS/DMF with an appropriate catalyst. One of them is HBr but I don't have HBr so I have to make it. TsOH might also be a very good idea but the problem is that can form salt with my haloketone complicating isolation. So my questions are: Which is the best method to brominate this molecule with pronounced basicity ? (no Br2 please ! ) ) and how to isolate the product (in base form not pyridinum salt) ? I really need the oppinion of an expert.... Sorry for my English...Thank you very much !