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6th September 2011 @ 06:11
Scale up of (+)-Dibenzoyl-D-tartaric acid for the resolution of R-PZQamine
MNR5-1%20scheme.png

MNR5-1%20table.PNG

Hazard and Risk Assessment:
HIRAC MNR5.pdf


Formation of anhydride intermediate (MNR5-1-INT)

MNR5-1-INT.png

A mixture D-(-)-tartaric acid (45.0 g, 300 mmol) and benzoyl chloride (122 mL, 1.05 mol) was heated to 130°C for 3 h and then allowed to cool to room temperature. The pale brown solid was washed with cold Et2O to give a white crystaline solid. The mother liquor was concentrated and the solid was washed with cold Et2O to give more white crystaline solid. Total solid recovered 99.85 g (293 mmol, 98%).

Hydrolysis of anhydride

The anhydride (99.85g) was dissolved in a mixture of toluene (300 mL) and water (30 mL) and heated to reflux for 2 h and allowed to cool to room temperature. The mixture was then concentrated under reduced pressure to give a thick, pale orange oil which was left to stand overnight. Some crystals formed but crude was still mainly oil. Crude taken up in a refluxing mixture of IPA/hexane (30%, 250 mL) and allowed to cool to room temperature then in an ice/water bath. What looked like product crashed out as a thick oil and did not crystallise. Everything was concentrated under reduced pressure, dried on high vac for 3 hours and stored in freezer over night which gave roughly 80% crystals to oil. The crude was dissolved with refluxing IPA/hexane (30%, 250 mL), further IPA (95 mL) was added to completely dissolve the crude then was allowed to cool and recrystallise as fine white needles.

Filtered, washed with hexane and dried under high vac.

Yield: 100.67 g

The mother liquor was concentrated for to recrystallise a 2nd crop.
Recrystalised in IPA/hexane (50:50).

Filtered, washed with hexane and dried under high vac.

2nd Crop Yield: 41.83 g

Total product recovered: 142.50 g, 298 mmol, 99%

1H NMR
mnr5-1_ed.pdf


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Attached Files
HIRAC MNR5.pdf
MNR5-1 table.PNG
MNR5-1 scheme.png
MNR5-1-INT.png
mnr5-1.zip
mnr5-1_ed.pdf