Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: azncuzin202 on April 19, 2013, 07:36:29 PM
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Can anyone suggest a plausible starting material(s) that could be used to form 4-methoxycyclohexanone? I don't need the mechanism but I'm having a hard time choosing a good starting material.
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Are you studying Claisen condensation reactions?
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Are you studying Claisen condensation reactions?
Not exclusively currently but yeah.
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Are you studying Claisen condensation reactions?
Not exclusively currently but yeah.
I can foresee this as a possible Claisen product, after hydrolysis and decarboxylation. However, I wasn't in class to know if other possible reactions might apply.
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Yeah the Claisen Condensation seems good but is there another plausible method?
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Birch reduction of differentially protected hydroquinone? Again, I missed your class.
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Anyone think 4-methylcyclohexanol is possible starting material?
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Anyone think 4-methylcyclohexanol is possible starting material?
No.
Are there any other conditions or constraints on the kinds of starting materials?
Like all synthesis problems, you need to know all your reactions: what they start with and what they produce. If you don't have a solid grasp on them, you won't have any idea how to proceed. As others have mentioned, putting the target into the context of the kinds of reactions and products you've been studying lately is a good practical tip.
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Anyone think 4-methylcyclohexanol is possible starting material?
No.
Are there any other conditions or constraints on the kinds of starting materials?
Like all synthesis problems, you need to know all your reactions: what they start with and what they produce. If you don't have a solid grasp on them, you won't have any idea how to proceed. As others have mentioned, putting the target into the context of the kinds of reactions and products you've been studying lately is a good practical tip.
Why not? There are no set conditions. As long as it can be found in http://www.sigmaaldrich.com/chemistry.html , there are no restrictions. This is a fairly open-ended problem. I can freely manipulate the reagent conditions.
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Does 4-Oxocyclohexanecarboxylic acid sound better?
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Does 4-Oxocyclohexanecarboxylic acid sound better?
Do you know a good way of converting the acid to a methoxy group?
Are you thinking about your answers or randomly guessing?
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I'm not an expert on organic synthesis, but your question isn't a typical one asked. You can start with any starting material, if you want to "play" with all the synthetics steps. With a straight chain alcohol, you can make any ethers, and with ethers, you can make all sorts of orgainic starting materials. If someone is in the mood to do a synthesis as difficultly as possible, you can start with anything. Look at this challenge: http://www.chemicalforums.com/index.php?topic=61257.msg218660#new someone wants to make a complex pharmaceutical, and they decided to start with methane gas. So you're really going to have to answer for yourself, what does this question mean, when it asks for starting material. Everyone else is trying to ask what you've learned recently, because we figure that's the point of the exercise. Or maybe you've been given a "lost on a desert island" problem, where you make any organic compound, from the simplest organic skeletons, and you're told you can use "any inorganic reagents" and we assume, this is one of those desert islands with abundant easily isolated rare-earth elements, pressure vessels, and cryogenic storage for liquid ammonia. ::)
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I apologize for giving incomplete instructions. However yes, this question is purely theoretical in nature. It is essentially an end of semester assignment where we are allowed to use any reaction and use any reagent to synthesize a product. It is not specific to a chapter or section thus the reason I said this was open-ended.
With that said, I have come up with a reaction that uses Williamson Synthesis. The starting material is 4-hydroxycyclohexanone and I use it to react with sodium hydride with THF solvent. This removes the hydrogen from the alcohol and forms hydrogen gas leaving a sodium ion. From there, I react the product with methyl iodide using heated acetone as the solvent. The methyl group from the methyl iodide attaches itself to the oxygen of the intermediate giving 4-methoxycyclohexanone as the primary product and sodium iodide as the minor.
Anyone think this is a possible mechanism?
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Anyone think this is a possible mechanism?
Now you've got something. Seems a little simple (just one step) for an end of semester assignment, but if there were no limits on the kinds of starting material allowed then that is one possibility.
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Now you've got something. Seems a little simple (just one step) for an end of semester assignment, but if there were no limits on the kinds of starting material allowed then that is one possibility.
Yeah, that's why me and my partner are feeling so skeptical. The instructions just said that as long as the reaction was in the textbook and the reagents could be found on the sigma-aldrich catalogue, it was okay. Is there anything wrong with the mechanism itself though?
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I find two things troubling. Is 4-hydroxycyclohexanone in the Aldrich catalog? Cyclohexanone undergoes an aldol condensation with hydroxide or alkoxides.
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Yeah, 4-hydroxycyclohexanone is in the catalogue. http://www.sigmaaldrich.com/catalog/product/aldrich/t292184?lang=en®ion=US
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Cyclohexanone undergoes an aldol condensation with hydroxide or alkoxides.
It probably depends on how sophisticated the instructor is. Side reaction is certainly a concern for maximum yield. Could you make the case for adding 1eq of NaH in a sea of CH3I? Perhaps. Alpha-methylating the ketone might creep in.
Otherwise- he needs to think about protecting group strategy. Mask the carbonyl before alkylating. Certainly makes the assignment more interesting- and shows more sophistication.
By the way--- this is a known compound with actual preps in the literature.
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Would alpha methylation be guaranteed or would it only give a minor product?