Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: AlphaScent on November 06, 2012, 10:18:28 AM
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I hydrolyzed compound 1 to compound 2. TLC is not showing what I would have liked. There is movement of compound 2 in a 2:1 hexane/EA and cannot be distinguished from compound 1. My boss and I were talking and he wants me to wash in 5% KOH and then extract with ether. Then wash with 1 N HCL until acidic. I think this is ok, but does anyone have any advice?
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re-crystallization is the purification method, but may be tricky due to impurities
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What you have done here is a transesterification, i.e. replace the ethyl ester with the methyl ester. To do a hydrolysis of the ester you must have water present. Why not just reflux in aqueous KOH?
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I understand a transesterification is possible. My professor says that it should go to the carboxylic acid. I had the same question, and this is why I believe I am washing with aq. KOH.
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That will not be enough. I would warm it gently to about 40°C with the KOH/water then work up as usual.
Transesterification is more than possible, it is definite. As I said to hydrolyse an ester you require the presence of water if you are going to do it with a base like KOH.
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Upon acidification it would yield methyl ester I suppose. I assume that is why he wanted me to do a base/acid wash. I am going ahead and gently heating. Then extracting with ether and washing with 1N HCl. Get back to you in a few hours.
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Just follow the progress by TLC. Then work-up when all the SM is gone.
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It worked and t seems my boss agrees with me (you) that it is better just to hydrolyze in water. He kept saying you need to add sodium methoxide for it to form the methyl ester. The TLC plate below was run 2:1 EA to hexanes. Thanks again, you are always a help disco!!
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Well done on a complete reaction ;D