Synthesis 1 (AS02) 1 from 0 (attempt 2)¶
After the weekend, a murky brown colour resulted. Upon the advice of a peer, the product was dumped into 500 mL of water, causing it to crash out of solution. the resulting precipitate was vacuum filtered and washed with distilled water.
The product was dried under vacuum before being redissolved in DCM and reduced under rotary evaporation.
The reduced, crude product was separated by column chromatography, with silica gel 60 as the solid phase. The product was colourless in solution, so TLC was run on each fraction and was compared to a stock sample of 1.
After a period of time, It appeared that nothing was being eluted from the column, so the liquid phase (DCM) was polarised with MeCN in a ratio of 40:1
The column still didn’t seem to be eluting anything at all, so in going back to a fellow research group member’s research, it would seem that the methodology for crashing out the product in water may not have been the best idea:
“... The solution was left to reflux at 130\(^\circ\) C. The reaction was left overnight, then was left to cool to room temperature. The appearance of a crystal precipitate began to form. The black-brown solution was then filtered and washed first with cold methanol, then with cold hexane. the dry precipitate was then weighed…”
After trying to evaporate off the aqueous filtrate only to obtain large crystals of (presumably) acetic acid, and running the column for 4 hours with no organic products being eluted, I have decided to start fresh tomorrow.
In doing some density/volume calculations, I am now thinking that I may not have added enough hexylamine and will use a syringe to measure it tomorrow. Measuring a very small quantity (\(<100\) mg) of liquid precisely by mass can be incredibly difficult.
Tomorrow I plan to redo Synthesis 1 (AS01) 0 1, however I will leave it running for 4 hours at 120\(^\circ\) C before allowing the reaction to cool down overnight and purifying it on Wednesday (16/1) morning, when a peer with experience in this particular synthesis will be around to help me.
Suraru, S. L.; Würthner, F. Strategies for the Synthesis of Functional Naphthalene Diimides. Angew. Chemie - Int. Ed. 2014, 53 (29), 7428–7448. https://doi.org/10.1002/anie.201309746. ↩