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Here I have a Chemistry Olympiad question I'm doing that outlines the synthesis of Ritalin. So far I've worked out A, Anion B-, and compound C (You can see my workings, as I've scanned and attached them here too).

How would I work out the structures of D, E and F?

I'm not familiar with all the mechanisms/reactions of nitriles and am unsure how to proceed - however, the olympiad is designed so that using fairly basic chemical understanding you should be able to work through the problems. Baring this in mind, how would I work out the remainder of the intermediates?

Here is the Olympiad question - all the information provided to me is here, and this is what you're given in order to work out the remainder of the intermediates in this synthesis

My workings so far

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  1. In A and B, you should probably draw the C-C single bond in the nitrile longer, it's a bit difficult to see at the moment.

  2. The nitrile is sequentially hydrolysed to an amide and then to an acid.

  3. Treatment with $\ce{ROH/H+}$ is a rather obvious Fischer esterification.

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You can arguably work all of this out from first principles: the nitrile carbon is electrophilic, and is therefore susceptible to nucleophilic attack by water. The reaction mechanism is given here. On top of this, the IR peaks strongly support the presence of amide and acid functional groups in D and E respectively.

With that said, I'd argue that there is always going to be an element of "I just know this because I read about it/was taught it before". The very fact that you said "I'm not familiar with the mechanisms/reactions of nitriles" indicates this - if you had happened to read a textbook chapter on nitriles, then you would probably have seen this, since it is one of the most fundamental reactions of nitriles. You would also have to read up about the IR wavenumbers - otherwise it's just gibberish.

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  • $\begingroup$ Thank you very much. In my A-level syllabus the reactions of nitriles are very limited and are not found in my textbooks - this is why I'm working through Olympiad papers, so I can familiarise myself with a wider range of Chemistry and ways to solve questions like this, as I've received an interview for Chemistry at Oxford. Ive seen you're an undergraduate and would very much appreciate some advice on the interview, I'm just doing Olympiad papers right now to improve. $\endgroup$ – Michael Harding Nov 19 '16 at 23:17
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    $\begingroup$ IR is gibberish, of course. */obligatory IR rant ;)* $\endgroup$ – Jan Nov 19 '16 at 23:25
  • $\begingroup$ @MichaelHarding feel free to pop into chat, I'm there often. $\endgroup$ – orthocresol Nov 19 '16 at 23:26
  • $\begingroup$ @Jan re: IR BOOM! $\endgroup$ – Todd Minehardt Nov 20 '16 at 2:19
  • $\begingroup$ Just as a point of interest, pyridine's pKa is 5.25, acetic acid's is 4.75. So, in E, that acidic proton should probably be more closely associated with the nitrogen than with the oxygen (I'd assume no matter where the proton is, there's going to be some cyclic intramolecular H-bonding). $\endgroup$ – orthocresol Nov 20 '16 at 19:05

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