Objective

To prepare N-tert-butyl phenylacetaldimine from phenylacetaldehyde and N-tert-butylamine

Procedure

To a N2 flushed 100ml round bottom flask t-butylamine ( 3.6ml 0.034mol ) was added to phenylacetaldehyde (4.1ml 0.034mol ).
The reaction was stirred with a stir bar for about 10 hours. A yellow precipitate of the imine was obtained. To this precipitate 2.6g of molecular sieves (Davison 3A grade 64) was added in order to dry it.


Results

Characterization of 36B

IR
1. IR of N-tert-butyl phenylacetaldimine (100microliters on NaCl disks after drying with 3A molecular sieves)
2.TLC of aldimine Vs aldehyde
3.36B Vs reactants
4.HNMR of 36B (100 microliters in 1ml of Benzene-d6)


Discussion

The IR spectrum of 36B which was obtained at t=20min indicates the disappearance of the carbonyl peak (of phenylacetaldehyde) at 1724 cm-1 . A strong absorbance at 1645 cm-1 suggests the formation of an imine.
HNMR of 36B suffers from severe peak broadening which might be a result of molecular sieves (which contain metals). Also since 36B was not completely soluble in methanol, the NMR tube contained solid particles suspended, which might have also caused the peak broadening. Therefore it is not possible to confirm the formation of aldimine.

Conclusion

This experiment has tobe aborted because a decent characterization of the imine is not possible.

Log


2006-10-21

5. 22:00] Added phenylacetaldehyde to t-butylamine with stirring and the reaction mixture immediately got cloudy and warmed-up.
6. 22:03 (approx)] A thick precipitate was formed
7. 22:15 (approx)] 2.6g of molecular sieves (Davison 3A grade 64) was added to the thick precipitate to obtain 36A.
7. 22:20] removed 100 uL using a micropipette to obtain 36B and obtained an IR using NaCl disks.

2006-10-22

8. 09:30] An NMR was also obtained.
9. 36A was partially soluble in Benzene-d6 and Methanol-d4.
10. Only a small amount of 36B was used in Exp 032, the remaining was stored under N2 and parafilmed in a round bottom flask.

Tags

Phenylacetaldehyde, InChI=1/C8H8O/c9-7-6-8-4-2-1-3-5-8/h1-5,7H,6H2
tert -butylamineInChI=1/C4H11N/c1-4(2,3)5/h5H2,1-3H3
N-tert-butyl phenylacetaldimine InChI=1/C12H17N/c1-12(2,3)13-10-9-11-7-5-4-6-8-11/h4-8,10H,9H2,1-3H3/b13-10+