Every method I have tried resulted in a very low yield (5%).
In method one, potassium carbonate and amine salt were dissolved in water, followed by the addition of DCM, and stirring for 15 mins (also 1H and overnight) at 0 degrees C. From what I understand, most of my amine was in the aqueous later. I tried extracting with DCM and EtOAc with no luck. Additionally, DCM seems to form an azeotrope on the rotovap.
In method two, I tried sodium hydroxide in methanol.
In method three, I tried potassium hydroxide. All of these procedures were obtained from SciFinder, but I did not achieve the results that the authors did unless it's very common to get a very low yield with this compound?
Hi,
its pKa is ~9.80. Thus, titrate the solution with sodium hydroxide until pH ~10 and then extract it with ethyl acetate.
In general the method described by @Ricardo J Ferreira is the method of choice however I prefer to use sat. K2CO3 (pH~11).
In this case, there is a reason why the compound is only available as •HBr. In the free base, you would have a good leaving group and a good nucleophile at the same time. Protic solvents (H2O, MeOH) support the attack of the amine.
In a synthesis, you can use it as it is and liberate the base in situ. But competition between leaving groups will still be an issu
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