I've done transesterification of vegetable oils and animal oils using H2SO4/MeOH many times before but this is the first time I'm doing it with the CE 1h-05 internal standard (C21-TAG) present. From the moment I added the MeOH a chunky white ppt formed which did not disappear. I reacted overnight at 50degC (as per Christie) and when I looked the next day there was still a white ppt. I'm assuming this is the C21-TAG that is not transesterifying. Am I right? What conditions are typically used for transesterification when using this IS?
Thanks John. I tried it again with toluene and at 65 degC for 1 hr and 40 mins and it worked.
John is right. The main problem is relate to solubility of TAGs. Toluene can help to solve this problem.
the reason is crystallisation of C21-acid. By dilution the problem was solved. It is similar to dewing technique in petroleum refining, to control appearance of first crystal dilute with toluene and to crystallise add ketone. The higher the dilution the lower the inclusion in the crystal structure
HELLO JONATHAN: USED MEOH KNOWING THE INDEX acidity OIL THIS ALLOWS YOU TO ESTIMATE GRAMS KOH, this you dissolve WITH MEOH, once dissolved LO ADICIONAS ON OIL TO HOT TO BE A
Dear Jonathan
Thanks for sharing your experimental description. I am sure addition of organic solvent helped and resolved your problem. In order to determine the faction of conversion of estertification; you may carry GC analysis for methyl-ester analysis for quantification. The above reaction can be carry out by acid or alkaline catalysts; even heterogeneous catalysts are preferable. Each method may have advantage and disadvantages. Further process purification may required for pure product.
Wish you good luck
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