Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: AlphaScent on September 11, 2014, 11:00:08 AM
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I am trying to figure the cheapest way to brominate 2-pentyn-1-ol.
I first thought Finkelstein may be the way to go via the mesylate. It is two steps though.
Then I thought triphenylphosphosphine and bromine, but it is costly.
Lastly, I thought about Phosphorus Tribromide. Will this work easily for propargly alcohols??
Does anyone have any experience??
This is done neat, right? With pyridine as an HBr scavenger???
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Finkelstein needs low temp to avoid allene formation.
PBr3 is probably the way to go.
Have not done either for a long time now :(
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I am not doing finkelstein.
I found a great procedure in a book by a chemist named Brandsma. Has exactly what I need.
Done in ether with a bit of pyridine at -35. Then bring to rt and reflux for 30 min.
Not bad.
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I cannot tell you whether this is good advice or not, but I'd look up your target compound. It looks simple enough that I assume it is known. (For kicks, I'd sometimes compare what they were paying me with the cost of trying a "new" route to a known compound. I didn't try too many new routes. It just wasn't worth it. That is also why I bought something if I could. Just sayin.)
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ORgopete,
I understand. We are trying to make starting materials so it is cheaper. On scale, it will be cheaper.
The PBr3 is the route to take here.
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PBr3 SURELY! As stated, you will get the allene with Finkelstein if the temp is not uber cold! Too expensive to conduct, and 2 steps as you said.
-Zack