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Author: Subject: 4-Benzylpiperidine
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[*] posted on 29-10-2018 at 11:21
4-Benzylpiperidine


Reductive amination between piperidine & benzaldehyde purportedly gives a ~96% yield of 4-Benzylpiperidine. This is somewhat surprising in that one would expect the reduction of the Schiff base to give the N-substituted tertiary amine.

Alinezhad, Heshmatollah; Tajbakhsh, Mahmood; Salehian, Fatemeh (2005). "Reductive Amination of Aldehydes and Ketones to Their Corresponding Amines with NaBH4 in Micellar Media". Monatshefte für Chemie - Chemical Monthly. 136 (12): 2029–2033. doi:10.1007/s00706-005-0362-3.
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Sigmatropic
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[*] posted on 29-10-2018 at 12:09


Must be some sort of typo, or otherwise it would be a very peculiar C(sp3) - H activation. Given that the paper is Iranian and the fact that it features Micellar Media as a means of publishing something completely unoriginal I wouldn't believe the claims made. But perhaps these sort of things happen when you run your reactions using mayonnaise as the solvent.
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clearly_not_atara
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[*] posted on 29-10-2018 at 12:14


If you look at the paper, the result for "4-benzylpiperidine" is right next to the entry for "4-benzylmorpholine" where the latter actually indicates N-alkylation. The authors do not comment on any unexpected results with piperidine. Possibly, whoever wrote up the article (probably a grad student) mistakenly thought that piperidine was numbered like morpholine with the N at 4.

piperidine_for_sm.png - 138kB




[Edited on 04-20-1969 by clearly_not_atara]
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Sigmatropic
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[*] posted on 29-10-2018 at 12:41


12,13 and 14 h reactions? Come on now, one does that sort of thing for cell based experiments but not chemical reactions...
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DavidJR
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[*] posted on 29-10-2018 at 13:13


Quote: Originally posted by Sigmatropic  
12,13 and 14 h reactions? Come on now, one does that sort of thing for cell based experiments but not chemical reactions...

I'm not sure where you pulled that idea from...
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Sigmatropic
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[*] posted on 29-10-2018 at 22:14


Surely starting a reaction at 0800, only to finish it at 2200 is not what anyone who actually does this day in day out would do, don't you think? Maybe it is different in your country but I don't consider that normal working hours.
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Metacelsus
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[*] posted on 29-10-2018 at 23:03


It's quite common to leave a reaction running overnight (say, 20:00 to 8:00 the next day).



As below, so above.
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Sigmatropic
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[*] posted on 30-10-2018 at 12:47


I don't consider 8 to 8 normal working hours but that'll depend on your location.

A 14 hour reaction with 5 portions of reagent is not the same as setting up a reaction and coming back the next day.

Now I will leave this discussion and keep these thoughts to myself next time.
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[*] posted on 30-10-2018 at 18:32


I hear about such reaction-times often in my research lab. Certainly for batch mode gas reactors like what I use, but the organic chemists also run 22hr, 14hr, etc. reactions and talk about them being pains. Often multiple grad students will be watching a reaction over its course.



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