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Topic: Methylation product  (Read 6666 times)

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Offline pallidol

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Methylation product
« on: August 23, 2015, 12:49:06 AM »
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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Offline phth

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Re: Methylation product
« Reply #1 on: August 23, 2015, 04:34:54 AM »
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
« Last Edit: August 23, 2015, 07:47:10 AM by phth »
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Offline Dan

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Re: Methylation product
« Reply #2 on: August 24, 2015, 02:04:38 AM »
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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Offline pallidol

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Re: Methylation product
« Reply #3 on: August 24, 2015, 02:29:22 AM »
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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Offline Dan

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Re: Methylation product
« Reply #4 on: August 24, 2015, 03:24:44 AM »
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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Offline pallidol

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Re: Methylation product
« Reply #5 on: August 24, 2015, 04:08:04 AM »
I loss one O group?
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Offline Dan

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Re: Methylation product
« Reply #6 on: August 24, 2015, 07:34:31 AM »
Yes I think so (dehydration).
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Offline pallidol

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Re: Methylation product
« Reply #7 on: August 24, 2015, 11:09:31 AM »
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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Offline pallidol

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Re: Methylation product
« Reply #8 on: August 25, 2015, 12:46:43 AM »
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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Offline Dan

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Re: Methylation product
« Reply #9 on: August 25, 2015, 02:33:09 AM »
Yes, that's what I think it is - via aldol condensation followed by methylation.
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Offline pallidol

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Re: Methylation product
« Reply #10 on: August 25, 2015, 02:48:26 AM »
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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Offline pallidol

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Re: Methylation product
« Reply #11 on: August 27, 2015, 05:14:37 AM »
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.
« Last Edit: August 27, 2015, 05:28:58 AM by pallidol »
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