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http://www.scientificupdate.co.uk/blog/item/solvent-work-up-tips.html?goback=%2Egde_3554645_member_25560753011 KEY SOLVENT AND WORK UP TIPS
WRITTEN BY DR JOHN KNIGHT, DR WILL WATSON ON WEDNESDAY, 08 MAY 2013. POSTED IN PROCESS CHEMISTRY NEWS
ELEVEN TIPS SOLVENT AND WORK UP TIPS FROM DR JOHN KNIGHT AND DR WILL WATSON OF SCIENTIFIC UPDATE.
1. Add 10% heptane to cyclohexane to avoid freezing at 4°C
2. Addition of 10% alcohol to hexane, reduces electrostatic hazards See for example T.J. Connolly et al (Raylo), Org. Proc. Res. Dev.,2000,4, 526
3. Addition of methanol to isopropyl acetate helps with solvent extraction See C.-y. Chen (Merck) in The Art of Process Chemistry, Chapter 4, page 117-142, edited by N. Yasuda, Wiley-VCH, 2011
4. Partitioning between heptane and acetonitrile (or presumably methanol) See A.C. Dahl et al (Lundbeck), Org. Proc. Res. Dev., 2008,12, 429.
5. Carry out extractions at higher temperatures, e.g. 50-70°C See for example M. Guillaume et al (Johnson & Johnson), Org. Proc. Res. Dev.,2003,7, 939
6. Adding 10% heptane or toluene to THF helps with phase separations with water
7. Similarly adding toluene to tert-butanol/water helps with phase separations
8. High pH helps phase separations with THF – water
9. High pH and high salt content can allow phase separations between IPA and water
10. If your material is not sensitive to base, potassium carbonate may be a better ‘salting out’ additive than the more usual sodium chloride. Potassium carbonate has very high solubility in water and of course higher ‘ionic strength’ to ‘push’ your organic material out of the water
11. Remember: solubility in mixed solvent systems is often non-linear – a compound may be much more soluble in a 50:50 mixture of solvents than it is in either of the individual solvents.
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