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22nd November 2011 @ 07:30
Samples MNR12-1 and MNR12-2 were combined and purified by column chromatography (silica gel, ethyl acetate:hexane 50-100 %). The products KAB2-1a and KAB2-1b were observed by TLC in ethylacetate before the fractions were combined and the solvent removed under reduced pressure.


KAB2-1a: 41 mg (fractions 77-88)
KAB2-1b: 58 mg (fractions 7-12)
Everything else: 95 mg

Total recovery: 194 mg
Amount loaded: 180 mg

TLC of crude MNR12-1 and MNR12-2 in ethyl acetate
Stain: KMnO4
Crude TLC

TLC of fractions 77-89


22/11/11: H-NMR was recorded for KAB2-1a. Very messy - Needs further tweaking/processing, possibly changing temp and diluting further. Also has ethyl acetate contamination.

note: The spectrum similar to the SciFinder predicted H-NMR.

23/11/11: The NMR sample prepared yesterday was further diluted in CDCl3 and the spectrum re-recorded. It was slightly cleaner. Need to process the data, results pending.
The KAB2-1 samples in CDCl3 were recombined and the solvent removed under reduced pressure. giving a clear oil, which was placed in the freezer overnight to promote crystallisation.

8:17 am - No crystallisation yet

The KAB2-1 sample was removed from the freezer and put under high vacuum. The remaining fractions (1-6, 13-76 and 89-111) were combined and the solvent removed to give a slightly yellow solid with a mass of 95 mg. The total recovery was 108 % of the amount loaded. Possible silica contamination from the column.

7:11 pm - Sample KAB2-1a was returned to freezer

8:17 am - KAB2-1a Still no crystallisation.

8:13 am - KAB2-1a Still no crystallisation. Sample removed from freezer and left at room temperature.

Sample no longer a gel, but a yellow solid. Attempt at recrystallisation from toluene and hexane.

Formation of small yellow crystals. Flask kept at room temperature.

Crystallisation complete. The small yellow crystals were washed in hexane then filtered.

1H-NMR recorded.

Yield: 27.8 mg, 19.3%
Rough m.p.: 109-120 C
Final KAB2-1

Recovery and yield for the purification procedure was poor. As of 23/01/12, no characterisation performed on the recovered crystals.

More Information here
Attached Files
Crude TLC
Scheme KAB2-1
KAB2-1 out of freezer
Final KAB2-1