I am trying to turn an aliphatic nitrile (with three identical CN groups on the same molecule) into a tert butyl ester. i synthesized the corresponding carboxylic acid and tried to turn it into tert butyl ester using DCC and DAMP but the results were not satisfactory (very low yield and tedious purification). I also used MgSO4 and H2SO4 (Failed again very low yield). I also tried using trifluoroacetic anhydride ((Failed again, very low yield). using SOCl2 also did not make any difference. now I am thinking about using pinner reaction to produce tert butyl ester. is it feasible? how about using the corresponding sodium carboxylate and tert butyl chloride?
Dear Sajjad,
many thanks for sharing this very interesting chemical problem with the RG community. Personally I have no experience with the Pinner reaction, so that I cannot give you any recommendation in that respect. My suggestion would be to think about the reasons why all your previous attempts (which all sound quite reasonable) failed. Could it be that your target molecule is sterically overloaded, so that the tri(tert-butyl) ester is just not accessible?
As for another attempt to make the ester compound I suggest that you first prepare the silver salt of your tricarboxylic acid (e.g. from the free acid and freshly prepared Ag2O) and then treat it with tert-butyl chloride. I think there is a good chance that this route could work.
Good luck with your research and best wishes, Frank Edelmann
Sajjad, unless you show the structure of you molecule, I doubt you you receive a useful suggestion. There are ways to make tert-Bu esters, but with three carboxylic groups it can be tricky, especially if you don't know their positions.
You can use tert- butanol in Pinner reaction involving conversion of cyanocompd. into tert -butyl ester .
Hi! In order to synthesize tert-butyl esters I used tert-butoxypyridine with boron trifluoride.diethyl etherate (https://doi.org/10.1016/j.tet.2018.05.050 0040-4020/). It worked well for me! Good luck!
Sajjad, now when you uploaded the structure of your target compound, I may suggest the better way to make it. See the attached scheme; the details can be found in patents US9856348, 2018, B2 and WO2014/152718, 2014, A1
Good luck,
Vladimir
Dear Sajjad,
I fully agree with the helpful answer provided by Vladimir Khlebnikov. The nitro-tri(tert-butylester) derivative has been frequently reported in the chemical literature, and it is indeed best prepared from nitromethane and tert-butylacrylate in the presence of Triton B as basic catalyst. For a detailed procedure please have a look at the attached freely accessible "Supporting Information" (pages 2/3) of the publication entitled "Efficient Synthesis of Branched Poly(Acrylic Acid) Derivatives via Post-Polymerization Modification". The authors report an isolated yield of 80%!
Good luck with the synthesis!
thanks Dear Frank T. Edelmann and Vladimir Khlebnikov. my first strategy was using TBA and nitromethane how ever I don't have access to TBA.
Dear Sajjad, thank you for your kind response and explanation. You're very welcome! Sorry to hear that you don't have access to tert-butylacrylate (TBA). The problem with TBA is that it is a technical product which cannot be easily made in the lab. Unfortunately the direct esterification of acrylic acid with tert-butanol is unfavorable because of the steric bulk of the latter. By the way, the nitro-tris(tert-butylester) derivative is also commercially available, but I assume that this doesn't help you much either. I suggest that you try the silver salt method which I outlined in my first answer. Chances are pretty good that it will work.
Good luck with your work and best wishes, Frank Edelmann
Sajjid,
From my experience, all chemists once in a while find themselves in a situation when they cannot get the preferable starting material for their work, and have no other choice but to make it. I can feel you pain.
Nevertheless, in my opinion, synthesizing tert-butylacrylate in the lab is still much easier than the making the full tert-bytyl ester of tri-acid that you need. There are numerous procedures to make tert-butylacrylate, and for this there are many options depending of you preferences and availability of the starting material.
In the lab I would recommend the reaction of tert-butanol with acrylic acid chloride or anhydride in the presence of Et3N/DMAP in an appropriate solvent. Combination of acrylic acid with DCC will also work instead of acid cloride/anhydride.
Good luck,
Vladimir
Hi Sajjad,
tert butyl ester could also be prepared via Acidchlorides. Have you tried thia ?
There are several possibilities to get acidchlorides, via Thionlychloride in simple or, in more problematic cases PCl5
Regards
Andreas
Dear Dr. Frank T. Edelmann. I will try the Ag2O method. thank you for your kind response.
- Badges
- Science method