Objective

To check the stability of the furan ring of 5-Methylfurfurylamine (5-MFA) in TFA to investigate the behavior of furan containing Ugi products. According to the proposed mechanism, a similar elimination of ammonia is expected for 5-MFA

Procedure

A solution of 5-methyl furfurylamine (223uL, 2mmol) and pure TFA (3mL) in a 10ml round bottom flask, with a condenser was heated for about 30 min under N2.

Results


5-Methylfurfurylamine
H NMR

112A (Before heating)
112B (After heating)
112BT1(until start of reflux is determined we don't know the reflux time)
112BT2
112BT3

Discussion

It is possible to determine the amount of starting material remaining after T1 and T2 by looking at the ratio of furan H's to the TFA peak. Also discuss the new peaks that show up.

Conclusion

The furan ring is shown to be unstable when dissolved in pure TFA and refluxed for about 24 hours, however it survived for the first half an hour at least.

Log

2007-07-16

14:40 Added TFA (3mL) to 5-methyl furfurylamine (223uL, 2mmol) in 10ml single necked round bottom flask with a reflux condenser, this is 112A Video of setup
14:41 Measured 100uL of solution 112A and dissolved it in CDCl3 (800uL)
14:47 Started heating and stirring solution in flask (variac setting 80),
14:53 The solution started to reflux.
15:13 Stopped heating (solution was boil over into the condenser), took out of sand bed to cool, this solution became 112B-T1
15:16 Measured 100uL of solution from flask and dissolved it in CDCl3 (800uL)
15:37 Obtained HNMR of 112A
15:39 Obtained HNMR of 112B-T1 (after heating)
15:41 Put solution in flask back on heat with variac setting at 80.
15:47: The solution started to reflux.
15:55 Turned heat down to 40.
16:25 Took flask with solution off of heat, this is 112B-T2
16:37 Measured 100uL of solution 112B-T2 and dissolved in CDCl3 (800uL)
16:44 Obtained HNMR of 112B-T2 (after second heating)
17:00 Starting heat again under same conditions (variac setting at 40), stirring

2007-07-17

11:45 Removed the flask from heat source. The solution was refluxed overnight.
12:31 After the solution had cooled a few drops of it was taken up in CDCl3 (800uL) in an NMR tube and an H NMR was obtained, this is recorded as 112B-T3.The solution remained almost insoluble in CDCl3.