I synthesized sodium oleate this past week from a near equimolar solution of NaOH and Oleic acid with the base in slight excess. Since the product is so viscous in solution, I decided against drying it on the rotovap. Instead, I slowly evaporated off the solvent (ethanol) then placed it in the oven at ~140°C. The compound's melting point is over 200°C yet after 12 hr, the product was still not dry and actually had charred in the oven.
How can a fatty acid salt burn below its own melting point?
Have you tried vacuum drying ?
If not, you may try a vacuum oven for this. Please use a cold trap with ethanol-dry ice / ethanol - liquid nitrogen as coolant. The cold trap should be placed between the oven and the vacuum pump. Suitable temperature for drying can be found by trying out.
Hope, this works for you and best wishes for that.
Storage temp of sodium oleate: -20 0 C ! Why?
Melting temperature 232-235 0 C.
Sodium oleate molecule has a double bond, which is oxidized by atmospheric oxygen by the mechanism of the formation of free radicals (cold combustion).
If you want a pure sodium oleate, then you need to mix equivalent amounts of pure alkali and pure acid in ethyl alcohol. Then evaporate the alcohol in the cold under vacuum.
Best regards.
Yuri, that is the answer that I was seeking - thank you. I didn't think the double bond would be much of an issue since the SDS for oleic acid doesn't mention any special storage conditions. Then again, it is typically stored in a capped amber glass bottle.
Ashish and Yuri, thank you for the responses. Enjoy your days
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