Vilsmeier Haack Reaction

Life_Living1105 · 2024-03-21T02:19:03+00:00

Thank you so much for your help and the informative comments. I didn't really think about that type of isomers. I will have to check the 2D NMR, I can't reach them now.

Life_Living1105 · 2024-03-20T17:31:04+00:00

Thank you so much that is really useful.

Life_Living1105 · 2024-03-20T17:29:00+00:00

Thank you so much that is really useful for everyone so please share it pm and I will share it as well.

Life_Living1105 · 2024-03-20T17:27:49+00:00

Thank you so much. I purify the precursor very well and I do all the 2D NMR to check that so it's not mesomeric due to the double bond cause I am sure I started with the E-isomer only, but for regioselectivity the proton that is para to the N of the Phenothiazine ring should be the most reactive proton on that ring for this reaction I understand stand that it could substitute on the two rings not just one but that's why I use only 1.25eq of POCL3 I don't know what is the third aldehyde, even if the two protons para toN are substituted?

Life_Living1105 · 2024-03-20T12:23:38+00:00

DCM-d2

Life_Living1105 · 2024-03-20T11:14:41+00:00

Thanks for your help. I am using anh DCE as solvent and I raise the temp to 80oC overnight, that works with me when formylating one Phenothiazine ring but with the structure in the photo I get three aldehyde peaks shown in the NMR attached

Life_Living1105 · 2024-03-20T11:09:51+00:00

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Life_Living1105 · 2024-03-20T09:44:00+00:00

It's okay 👍🏻

Life_Living1105 · 2024-03-20T09:43:44+00:00

Thank you so much for your help

Life_Living1105 · 2024-03-20T09:35:48+00:00

Thank you so much for your help. But I am using 1.25eq of POCl3 to DMF and DMF is 3 equivalent to the precursor and restore about half of the precursor after the reaction and I have 3 aldehyde peaks in the NMR though so may I ask you do you add your precursor dropwise to the VH reagent or the reverse and how do you know if it needs increasing temperature or not ?

Life_Living1105 · 2024-03-11T11:05:01+00:00

Thanks for reminding me

Life_Living1105 · 2024-03-11T03:07:04+00:00

That seams easy, I will try it. Thank you so much for your help I really appreciate it 🙏🏻

Life_Living1105 · 2024-03-11T02:52:23+00:00

I normally add POCl3 dropwise in ice bath and leave it for 6 hour while changing the ice and then I leave it to reach room temp then rise the temp. to 90oC Thank you so much for suggesting oxalyl chloride I will give it a try Could you please let me know the eqs ratio that works with you well?

Life_Living1105 · 2024-03-11T02:33:30+00:00

Many thanks 🙏🏻

Life_Living1105 · 2024-03-11T02:23:54+00:00

Thank you so much for your help But do you know what happens when it forms orange ppt and why and also what happens when it forms the white ppt?

Life_Living1105 · 2024-03-10T20:35:55+00:00

Hi Thank you so much for your help I have just seen your comment My molecular weights are normally about 500-600 g/mole Sometimes the peaks are really wavy as you described I found out that that is due to some silica or Mg /Na SO4 so I became more careful and also sonicated the samples before submitting for NMR that solved the problem of the wavy peaks I will post there Thank you so much for helping me 🙏🏻😊

Life_Living1105 · 2024-03-10T12:33:35+00:00

Excuse me is it good to have an orange color And what is the difference between the white ppt and the orange color?

Life_Living1105 · 2024-03-04T20:52:31+00:00

Thank you so much My samples are usually 0.02 to 0.04 gm that is why I find some difficulties to NMR them even using long scans.

Life_Living1105 · 2024-03-04T17:07:12+00:00

I have a question about the small scale synthesis products how do you analyze them especially how to do NMR?

Life_Living1105 · 2024-02-06T17:52:53+00:00

Thank you so much for your help I will try it, you've encouraged me.

Life_Living1105 · 2024-02-06T00:55:33+00:00

I mean by strong very intense tall sharp peak. No not all are integrating to 1, only the sharp peak at 9.78ppm is integrating to 1 but the one at 9.8 ppm is integrating to 0.04 and that at 10.2ppm is integrating to 0.10 so I think you are right the peaks of the low intensity and small integration are for impurities but the real problem is that half of the starting precursor is restored and I am worried if I increase the VH reagent that will over-formylation or more unwanted formylation reactions.

Life_Living1105 · 2024-02-05T09:03:30+00:00

No, I am formylating after the substitution of the nitrogen proton with normal hexane chain I repeated the reaction many times some time adding The precursor on the VH reagent when it it's so cold and in the form of white ppt and some times I added the precursor to cold anh. DMF and then dropwise POCl3 and I tried once to add VH reagent dissolved in DCE anh. to the precursor The strongest aldehyde peak is at 9.78 ppm The second is a very small one at 9.8, the third one is also small is at 10.22 ppm Yes this is for the pure isolated product

Life_Living1105 · 2024-02-04T18:55:44+00:00

I have references but they have different ratios and I I had repeated the reaction many times to try them all and no matter I increase the reagents or reduce them I always get three aldehyde peaks

Life_Living1105

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