To purify crude phenylacetaldehyde by vacuum distillation.


10ml of Phenyl acetaldehyde was taken in a 100ml round bottom flask and distilled under vacuum at about 7 mm Hg. (Pictures of the setup one and two).


Monitoring of the distillation temperatures

Excel Data sheet

Characterization of 039B

JCAMP Format HNMR (4 ml)
TLC of all three fractions Vs Crude.


The HMR for 039B is very clean, although a clear triplet is not seen for the aldehyde peak.
The problem with bubbling over can be eliminated by using a stirring bar in the future.
The theoretical distillation temperature for phenylacetaldehyde at 7mm Hg is expected to be 65C (195C at 1 atm ) The observed temperature at which fraction 039B was collected was Tu 80 C. The discrepancy may be due a reduction in the vacuum over the course of the distillation.


The distillation was successful.



16:45] 10ml of crude phenylacetaldehyde was pipetted out in a 100 ml round bottom flask (shown in the picture above), a vacuum distillation head was attached to it.
1738] Vacuum stabilized at about 7mm Hg and the Tu (temp of the vapors) still remained at 21C. Turned rheostat was gradually turned on to 70 .
17:45] The crude liquid in the round bottom flask started to shoot high, although it did not seem like it got in to the collecting tube, the Tu shot up to 70 C and temperature of the liquid (Tp) in the rb was recorded as 123 C and Tu was 70 C.
17:54] To stop violent boiling the vacuum was broken and a couple of boiling chips were added to the hot crude phenylacetaldehyde Tu= 80 C, Tp = 130 C
17:57] First fraction (039A) collected (2 ml) (Tu87 C, Tp 130 C)
18:09] Second fraction collected (039B) 4mls. (Tu79 C Tp 163 C)
18:20] Third fraction collected (039C) 2ml (Tu65 C Tp 180 C), stopped heating and released the vacuum


Phenylacetaldehyde, InChI=1/C8H8O/c9-7-6-8-4-2-1-3-5-8/h1-5,7H,6H2