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Margel

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Everything posted by Margel

  1. Chemist, I now doubt if you really what you are talking about. Jones reagent is a standard oxidation reagent which works for a lot of substrates even strained molecules. Type chromium trioxide on Organic Synthesis website to know what I am talking about. The problem with Jones reagent is its selectivity. This is why PCC, PDC, Swern etc. was invented. Hydrolysis of nitriles involve an excess of water. Jones oxidation is carried out with not much water. So it is really not likely that hydrolysis is the problem. Besides, the COOH peak can be easily seen in the 1H NMR spectrum. My supervisor did 2 postdocs and one is with one of the editors of EROS. Using KMnO4 alone results on several oxidation problems. I agree with Sundberg and Carey on this. However KMnO4 in a solid support (like CuSO4, SiO2 or alumina) is know to be effective oxidizing agents producing high yields of the desired product. But certainly, you have sone point on the nitrile coordinating with chromium so I owe one to you. I already mentioned that SN2 reaction of dibromoacetone is problematic and here you are suggesting me to start with glycerol. It seems that you don't have a good eye for details.
  2. KMnO4 can cleave the double bond so 3-hydroxypropanoic acid (IUPAC name) is one of the possible products. KMnO4 is a very strong oxidizing agent and this is why chemists usually used milder oxidizing agents such as Jones reagent, PCC, PDC etc. . 3-hexenoic acid is the major product if the oxidant will not cleave the double bond. The structure you have drawn is a carboxylic acid. No, it is not a diol.
  3. Wow, thank you all for your replies. Certainly, I got some cool ideas from your input. Based on NMR, there is really no sign that hydrolysis is occurring. There is at least 95% S.M. . The reaction is monitored every few hours then everyday. (Remember that ester hydrolysis in acid is slow, how much more a nitrile which is even more resistant to hydrolysis than an amide). Also sodium hypochlorite or chlorine are weaker oxidizing agents compared to chromic acid i.e. according to my supervisor. He can only suggest KMnO4. Having 2 electron withdrawing groups on my substrate really makes this oxidation hard. Also I do not have problems of functional group compatibility with CrO3 neither solubility problems. My problem is its reactivity. As for the number of equivalents of CrO3, I already added a lot of excess CrO3/ H2SO4. Most procedures actually used 1.1 eq. So far, I have not gotten a very helpful information yet.
  4. Chemist, I really appreciate your reply. But perhaps I did not explain everything clearly. CrO3/H2SO4 is already a strong oxidizing agent. My substrate 3-hydroxyglutaronitrile did not even show a small sign that oxidation is occuring using this reagent (based on NMR, mostly S.M.). Both Swern and Dess Martin I believe are weaker oxidizing agents and therefore I don't think they will produce better results. I am now wondering if a super oxidizing agent exists ?
  5. Thank you UC for your reply. What I really mean is CrO3. Sorry for the mistake. This is a problem which I need to be solved as soon as possible as this will be used as a starting material. I cannot think of any other shorter route to the ketoglutaronitrile. So I guess I could try making the acid first then convert to amide then dehydrate. I still wish there is an easier way to prepare this compound. I also cannot believe that this compound has only 1 entry in scifinder and that paper did not even have a procedure or characterization data.
  6. Hi to all. I am a synthetic chemist with a difficult problem. I wanted to oxidize 3-hydroxyglutaronitrile to a ketone. I already tried using the standard Cr2O3/ sulfuric acid method. However, after 9 days at 85 oC I only got some crap and some starting material. I understand that the electron withdrawing groups (2 nitrile groups) are making this oxidation difficult. Anyone? Help please. (I am now investigating this oxidation because SN2 reaction of 1,3-dibromoacetone to 3-ketoglutaronitrile using KCN is very problematic. I tried using diferent solvents such as DMSO, DMF etc. but still no reaction.)
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