[LiAlH4]

Dear all,

I am doing a research project on ultrafast vibrational spectroscopy of phenols. The compound I am currently working with is 2-cyanophenol. The problem is that I need to substitute the OH hydrogen atom with deuterium (at least 90%). In case of normal phenol we can just reflux and provide fresh D2O so it is very simple. In case of 2-cyanophenol we cannot really reflux it for a long time because the CN group would hydrolyse. One of my ideas was to use NaOD to subtract the labile hydrogen atom, then using rotary evaporator we get rid of the solvent. Then, we use fresh D2O, add DCl and extract 2CP with chloroform for the measurements. Unfortunately, the spectrum shows only about 70% substitution and is contaminated with some traces of DCl, which is soluble in CDCl3.
Additionally, we cannot evaporate the solvent completely to obtain crystalline product because it would exchange the hydrogen with the water vapour.

Does anyone have any idea? I have spent weeks working on this and still I can not get my desired sample.

Thank you in advance

[curiouscat]

Do you make or buy the 2-cyanophenol?

[LiAlH4]

We buy it from Aldrich. It is a pretty nasty compound. It easily turns pink and smells really bad...

[orgopete]

Reflux? From my experience, if you had a phenol or even a much less acidic OH, adding D2O to a sample in an NMR tube is sufficient to exchange the OH to an OD. I would take my cyanophenol, add D2O or CD3OD, strip it down on your rotary, repeat to desired incorporation level.

[curiouscat]

Reflux? From my experience, if you had a phenol or even a much less acidic OH, adding D2O to a sample in an NMR tube is sufficient to exchange the OH to an OD. I would take my cyanophenol, add D2O or CD3OD, strip it down on your rotary, repeat to desired incorporation level.

"In case of 2-cyanophenol we cannot really reflux it for a long time because the CN group would hydrolyse."

[orgopete]

Reflux? From my experience, if you had a phenol or even a much less acidic OH, adding D2O to a sample in an NMR tube is sufficient to exchange the OH to an OD. I would take my cyanophenol, add D2O or CD3OD, strip it down on your rotary, repeat to desired incorporation level.

"In case of 2-cyanophenol we cannot really reflux it for a long time because the CN group would hydrolyse."

Did I miss something here? I never refluxed or even heated my NMR sample, I just added a drop of D2O and shook it. (I sure there are many others with similar experience.) If rotovaping is too vigorous, then freeze the sample and lypholyze it or use deuteromethanol. Repeat to desired content.

[curiouscat]

Reflux? From my experience, if you had a phenol or even a much less acidic OH, adding D2O to a sample in an NMR tube is sufficient to exchange the OH to an OD. I would take my cyanophenol, add D2O or CD3OD, strip it down on your rotary, repeat to desired incorporation level.

"In case of 2-cyanophenol we cannot really reflux it for a long time because the CN group would hydrolyse."

Did I miss something here? I never refluxed or even heated my NMR sample, I just added a drop of D2O and shook it. (I sure there are many others with similar experience.) If rotovaping is too vigorous, then freeze the sample and lypholyze it or use deuteromethanol. Repeat to desired content.

Sorry. I misinterpreted your answer.

I took "Reflux?" to be a sugesstion. Now I see it was not.

[LiAlH4]

Thank you very much for your replies. I have not tried freeze drying but it might be a good option. Unfortunately, 2-cyanophenol does not want to exchange his hydrogen easily, which is not the case when 3- or 4- cyanophenol are used. It might depend on how much the OH group is accessible to the solvent.
Solubility in D2O is very poor so using CD3OD would be definitely better, however, it is quite pricey.
I am not making a NMR sample. I need to completely exchange the hydrogen to deuterium for my IR studies. I would like to find out how the isotope substitution affects the internal rotation dynamics of the OH group and the dipole moment function of the CN stretch mode. Since CN group exhibits different temperature behaviour when interacts with the OD group (instead of OH), I need to study the extreme case that is nearly 100% deuterated 2-cyanophenol.
If you have any other ideas please let me know.

Thank you very much