Hello,
I am currently working on a project in which I am synthesising fairly large molecules with aniline-like functionalities. The next step is to functionalise the amine in order to obtain diethanolamine branches around the main molecule core.
The reaction I am following is between the aniline-containing molecule, a large excess of bromoethanol in the presence of base like NaHCO3 and solvent such as acetonitrile, reflux for 2 days. The workup I am extracting the product with DCM.
I am using this method as it should be an SN2-type reaction, although it seems not be working consistently and I am having sometimes problems isolating my product.
Any suggestion?
Thank you
Anilines are not that basic to react with weak bases like NaHCO3 to react with a primary halide unless the aromatic group has a electron withdrawing group (EWG). You either have to put a EWG on the N itself like Boc or Nosyl, or consider doing a reductive animation with an aldehyde like glycoaldehyde. A stronger base may work but the alcohol may interfere with this.
Please try with the following procedure (source: Mol. Cryst. Liq. Cryst. 1994, Vol. 247, pp. 91-97):
A mixture of 2-chloroethanol (177 g, 2.2 mol), aniline (93 g, 1.0 mol) and sodium hydroxide (96%, 91.6 g, 2.2 mmol) was stirred at 100°C for 3 days. The mixture was cooled to room temperature, extracted with
methylene chloride and washed with water. The organic layer was dried with anhydrous magnesium sulfate, concentrated and purified by recrystallization with diethyl ether/ petroleum ether.
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