schisto research community

content appropriate for schistosomiosis research

04 Nov


Published by RyanPakula

InChI is great and all, but today while exploring, I found two issues that bugged me.  The first arose from my simple double-checking exercise: I drew praziquantel at then took the InChI returned and plugged it into to see if it would bring up the appropriate page for PZQ (which I already knew existed).  I made the mistake of leaving one of the amide nitrogens as a carbon, so my search on chemspider returned that there were no hits at all.  Now, in this case that's fine, cause I messed u

03 Nov

"Successful" dehydrogenation

Published by RyanPakula

The sulfur melt dehydrogenation,

was carried out, with 9.5% isolated yield of the desired product and 69.3% recovered starting material.  Other products (observed by TLC) were not found after the column.

26 Oct

Dehydrogenation of PZQ and final EtOH recrystallization results

Published by RyanPakula

Trying to dehydrogenate PZQ using elemental sulfur.

Total yields including second batch of recrystallization are 86.4%, 74.34% (no second batch), 78.7%, and 80.1%, respective to 0x, 0.5x, 1x, and 2.5x hexanes volume to ethanol volume.

20 Oct

Ethanol and hexanes - initial results

Published by RyanPakula

V(hexanes) = 0.5*V(EtOH) resulted in the highest recrystallization yield at 74.34%.

Chromatography of PZQ

Published by RyanPakula on 20 October 2009 - 2:43am

Methods for the purification of PZQ can be collated here.
1. This paper describes the purification of enantiopure PZQ using "chloroform/methanol 0–0.3% MeOH as a solvent system."
2. This paper uses 1:1 EtOAc/petroleum ether ramping to pure EtOAc.
3. This paper uses "thick layer preparative chromatography [prep TLC] benzene/ethyl acetate 1/1, silica gel."

Recrystallization of PZQ

Published by RyanPakula on 20 October 2009 - 2:34am

This page details attempts to optimise the recrystallization of praziquantel. Anybody can add to/edit this page.
1. This patent (US patent 4,523,013) recrystallizes PZQ from "a mixture of petroleum ether and acetone," obtaining a 95% yield on the reaction.
2. This paper recrystallizes from ethyl acetate and hexanes to obtain a 70% yield on the reaction.

Purification of Praziquantel

Published by RyanPakula on 20 October 2009 - 2:31am

This is a parent page for improving the current methods for the purification of PZQ.

19 Oct

Ethanol and hexanes

Published by RyanPakula

EtOH with hexanes had wispy crystals; recovery was 43.98%; pure by NMR; Tm = 138.2-138.8ºC.  No crystals had formed from benzene sl'n nor toluene, so hexanes were added, and vials left at 5ºC.  Began EtOH with varying amounts of hexanes recrystallizations.
1 mL hexanes was added to the solution of benzene (1.4 mL), and 2 mL hexanes were added to the toluene solution (3 mL).  After a few hours at 5ºC, crystals have begun to form.

16 Oct

Ethanol results and a slew of other solvents

Published by RyanPakula
59.27% PZQ was recovered from ethanol heated to 50 ± 2ºC.  NMR was clean, Tm = 138.3 - 138.6ºC.
Began recrystallizations with water, ethanol, 50/50 water/ethanol, toluene, and benzene.
15 Oct


Published by RyanPakula

Toluene worked less-than-nicely for recrystallization, and a column to isolate the yellow/brown product failed.  This is likely due to the fact that a crude NMR of this product looks 99% identical to PZQ from the bottle.