After reacting a primary alcohol with TsCl I am using pyridine to react with the Cl. How do I purify the HCl from the desired Tosylate product?
Thank you, that could have potentially worked to increase yield. I used diethyl ether in which the PEG alcohol was soluble and the pyridine was not.
Hello Kathleen,
It all may depend on a number of factors, like: does contamination with a little of the primary alkyl chloride, that sometimes forms from tosylates, matter or not. The scale at which you are working can be important, too. The reaction can be run in a biphasic system, where your starting material is dissolved in CH2Cl2 (say 10-15 vol), and an excess of 2M K2CO3 (say 10-15 vol) is used as the base for HCl interception. You then add the TsCl, stir it rapidly, and monitor. If the reaction is slow, addition of 1-5% of a phase transfer catalyst (18-crown-6, tetrabutylphosphonium bromide, or the likes) can help. Tosylates of primary alcohols are quite reactive, so treat your mixture, and the product gently :). Good luck.
Dissolve PEG-OH in 5-10% aq. NaOH and add TsCl. The reaction mixture must be kept alkaline and may not be feel by TsCl. Extraction of the product with Et2O. See Schotten-Baumann method - http://www.synarchive.com/named-reactions/Schotten-Baumann_Reaction
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