Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Organic Chemistry Forum for Graduate Students and Professionals => Topic started by: pallidol on August 23, 2015, 12:49:06 AM
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Dear guys.
i would like to ask regarding my work. I did my reaction and and the column chromatography gave me three fractions . For fraction 1 and 2 the NMR are just fit enough. But i have problem
for the fraction 3.
From NMR, all the signal compatible to the structure A. Somehow during writing the mechanism it does seems not make sense otherwise i suggest the structure B as the product.
Could anyone give a suggestion regarding this matter.tq
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May sound simple, but I would take an IR or #3. Secondly, I would try this procedure K3PO4+18-crown-6 instead of NaOH. DOI: 10.1021/ie060899e Ind. Eng. Chem. Res. 2007, 46, 3016-3023
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I can't think of a reasonable mechanism for the oxidative dimer you posted.
It would help if post your NMR spectra, do you have MS?
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I only have NMR spectrums and have not do the MS analysis yet due to the instrument problem.
I attach here 1H, 13C and DEPT NMR spectrum. I have done HMQC and it just good enough to fit my structure-assumption of fraction 3(A).
tq for your concern. ;)
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I have an idea of what it is. I could be wrong, but:
Hint 1: Start by adding the enolate form of your starting material to the keto form of your starting material
Hint 2: I think the formula of the product is C23H22N2O3
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I loss one O group?
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Yes I think so (dehydration).
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yes i have tried to suggest the structure as a lactone unit and also in a spiro compound, but it seems none of it works.
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ok now i think i got the structure. But please correct me if i am wrong. It is quite close to the NMR of the chemdraw expectation.
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Yes, that's what I think it is - via aldol condensation followed by methylation.
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ok thanks a lot Mr Dan for the help. I am gonna run GC-MS within this two days to confirm it. I will update the result.
very much appreciate of your help. ;)
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i have done my GC-MS and there are several peak with the same molecular weight appear start from 28-30 minutes.
So I am pretty sure this is the structure. But somehow i am gonna analysis it using hr-ms within this two weeks.