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About Knumbnuts

  • Birthday 03/19/1951

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  • Interests
    Process research, Natural products synthesis, Organic chemistry. Medicinal chemistry.
  • College Major/Degree
    University of Bath, UK/PhD
  • Favorite Area of Science
    organic chemistry
  • Biography
    Too long to replicate here. But have spent a lifetime in organic chemistry
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Quark (2/13)



  1. Gentle hydrogenation over Pd/C removes halogen. Using a Rh cat e.g. Nishimura's cat hydrogenates the aromatic ring.
  2. Apparatus with ground glass joints is certainly a bit more expensive that individual pieces held in place with rubber bungs. But the expense is worth it. Have a look on e-bay you may well find apparatus quite cheaply there. If you look after it, like everything else, it will last forever, unlike rubber, which perishes over time. Anything that distills over in your "rubber apparatus" will be pure, unless it is an azeotrope, but even that will be pure! The whole point of distillation is purification so having stuff remain in the pot is ok. The trick is to know where to terminate the distillation.
  3. Labs do not use rubber stoppers these days, it's all ground glass joints. In the early days leeching of additives form the rubber by solvents etc was a problem. How do you know that nothing distilled with the isopropanol? Any additive will dissolve in the refluxing solvent and will not distill, as they are usually not volatile compounds. So if this is the problem they will concentrate in the distillation residue.
  4. If I see it correctly you have rubber stoppers connecting the bits of glassware? It may be that the isopropanol at reflux temperature has dissolved something out of the rubber, perhaps a radical inhibitor. You don't need much substance to get some colour.
  5. I think you should perhaps re-think the very first reaction, there is something else that could happen. It would help if you supplied some reaction conditions for the first step.
  6. It's probably a mixture of solids, salt, sodium chlorate, sodium hypochlorite (bleach). Most likely due to evaporation and decomposition. You can read more here: http://en.wikipedia.org/wiki/Sodium_hypochlorite
  7. Well you are correct. You generate the phenoxide anion which is more nucleophillic than the phenol. Thus is should react much much faster with the tosylate.
  8. Well you will not get a γ-butyrolactone if that's what you are looking for. Reduction of the carboxylic acid will give the alcohol if you use the correct reducing agent. Oxidation won't do much either, except give the amine-N-oxide, again it depends on the oxidation reagent.
  9. The longest chain is 5 carbon atoms long, pentatonic acid. The substituents are then included in alphabetical order. The numbers, the sum of which must be as low as possible.
  10. What about an F in the para position, does that vanish as well?
  11. OK, I sorted it out. It taught me to scan down the page! Here is what I am talking about in the above. epox.tiff
  12. The conversion from the disodium to the tetrasodium salt is done, as you say with sodium hydroxide. What you need to do is write a balanced reaction equation for this. From there you can calculate the number of moles and hence grams you require.
  13. You have gone from a 6 membered ring to a 5 membered ring upon reaction with benzylmagnesium bromide! Is this an error? I ask because the Grignard reagent will open the epoxide ring. On a side note how does one attach an image to a post?. If it was obvious then I would have posted the reaction I am talking about. Thanks for any clues to this.
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