Iam following the paper by Hyatt et al. but the mentioned coloured product isnt coming
Dear Samar Mujeeb thank you for your interesting technical question. In order to give you a qualified answer it would be very helpful if you could provide us with a few more details. I assume that you mean by "the paper by Hyatt" the following article:
Convenient Preparation of 2,7,8‐Trimethyl‐6‐hydroxychroman‐2‐carboxylic Acid (γ‐Trolox)
Article Convenient Preparation of 2,7,8‐Trimethyl‐6‐hydroxychroman‐2...
Unfortunately I don't have access to the full text of this research article. The term "trolox ester" is also a bit too unspecific. As shown in the attached schematic representation, trolox is a carboxylic acid, which can form a variety of different esters (methyl ester, ethyl ester, butyl ester etc.). Thus given only the original question it is nearly impossible to help you without knowing the experimental details. 😢
Dear Samar Mujeeb many thanks for the additional information and the paper. I assume that you mean the one-step preparation of trolox methyl ester as described on page 11. Did you use commercially available starting materials as received? I assume that particularly the methyl methacrylate should be freshly distilled prior to use because of its tendency to polymerize. Alternatively you should check if it contains a stabilizer. Thus this could be a source of error. In your original question you mentioned that "the mentioned coloured product isn't coming". The crude product is described as a "light tan solid". This could mean anything from off-white to light brown, gray, or even dark brown. In any case it is important that you obtain a precipitate upon cooling of the reaction mixture. The precipitate (no matter what it's color is) should then recrystallized from hot methanol. Thus you should redissolve the crude material in a minimum amount of hot (boiling) methanol, filter it through a folded filter and let the filtrate cool down to room temperature. This should provide you with the pure trolox methyl ester. Good luck! 😊
The precipitate I got is brown in colour and it is sticky. I poured ice cold water in the reaction flask after completion of reaction. After that I scraped out all the precipitate. And then I added methanol. The colour isn't changing to 'tan ' . Can we have other procedure?
Dear Samar Mujeeb as I said, don't worry about the color of the initial precipitate. After you added methanol to the crude product, heat the mixture to boiling until most of the solid dissolves. If necessary, add some more methanol. Then remove any insoluble material by filtration through a folded filter and let the filtrate cool down to room temperature. You can also place the flask in the refrigerator over night. This should give you the desired product. If it is still brownish, you can repeat the entire recrystallization procedure. Good luck!
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