Seeking advice on the methylation of oleic acid?
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Our method involves taking 0.1 g of oleic acid sample and placing it in a 5 ml volumetric flask; anhydrous methanol is added, and the mixture is heated in a water bath until dissolved. Then, 5–8 drops of concentrated sulfuric acid are added, and the mixture is shaken thoroughly. After waiting for ten minutes, 3–4 ml of distilled water and 0.5–1 ml of ether are added. The mixture is shaken vigorously for 1 minute, allowed to settle so that the layers separate, and the upper ether layer is then used for chromatographic analysis. 'However, oleic acid and linoleic acid cannot be separated in the chromatogram. I would like to ask experts whether there is a better methylation method
This post was last edited by flks224086 on 2009-5-25 19:20. The fact that oleic acid and linoleic acid cannot be separated may not necessarily be due to incomplete methylation; it could also be because the chromatography separation conditions are not optimal. However, your methylation method isn’t very good; if sulfuric acid is used as a catalyst, reflux is necessary, and the reaction is not complete within just a few minutes – it’s better to carry out reflux for more than an hour. Another relatively fast method is to use diazomethane as a catalyst; no heating is required, and the process can be completed in 2 minutes. Another option is to use boron trifluoride as a catalyst, in which case 3 minutes in a water bath at 90 degrees is sufficient. However, diazomethane is toxic and explosive, and boron trifluoride is also toxic; extreme care must be taken when handling them to ensure safety. You can refer to the following post: http://bbs.hcbbs.com/viewthread.php?tid=266857&highlight=%D6%AC%B7%BE%CB%E1
This post was last edited by Zhongxing Ren on 2009-5-25 22:10. Thank you, I’ll give it a try
Reply to 1# Zhongxing Renhe: I also need to carry out methylation now. Do you have any better methods available? My QQ is 379182499
Reply to floor 4: There isn’t one yet, but we’ve replaced it with imported columns, and the performance is decent now
Is extraction used because sulfuric acid causes significant damage to the column?