DogWhites
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New to Forum/Questions about the synthesis of Butyramide
Hello everybody I'm new to hobby chemistry (well about a year on but have done only minimal experimention. I'm interested however in the synthesis of
propylamine or some other primary amine, starting from carboxylic acids.. no plans for these compounds, just purely excercise if anything more than
hypothetical.
Now, from what I've read the last step could be a Hoffmann rearrangement from Butyramide, this is well documented for other amide->amines so unless
anyone knows something i don't about using it for this particular compound, I think this part should be cake.. It's getting to the Butyramide that is
bugging me. I know there are some pretty advanced ways of doing this with some serious reagents (bad phone.. if anyone is inretested I will try to
find some of the literature and post links when I'm on my computer, sorry) but from a beginners point of view I've only considered two.. One is the
thermal dehydration of ammonium butyrate and the other is forming the amide via the aldoxime (might be more heavy duty than I had realized though).
Now obviously we know which would be less work, (if starting material is butyric acid one would have to reduce that to the aldehyde before treating
with hydroxylamine, never mind the actual reaction to get to amide) I guess my question is mostly about the thermal ammonium butyrate to Butyramide
route.. I've seen this for shorter chained species but there is not much specifically on this one online that I have seen and its kinda got me
scratching my head. Im hoping one of you greater minded/learned folks could shed a little light on this for me? Also if there is some literature you
could point me to that would be really cool. I'm not the most computer savy person in the world and so far besides checking on here I have been using
google scholar and orgsyn to look stuff like this up. If there is anywhere else you folks would recommend just let me know. Thank you!
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Metacelsus
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See:
https://erowid.org/archive/rhodium/chemistry/amide.preparati...
https://pubs.acs.org/doi/abs/10.1021/jo01369a022?journalCode...
For the ammonium salt method:
| Quote: | | The temperature at which the acid is heated is sufficient to dehydrate a small proportion of the higher amides to form the nitriles. This reaction
becomes appreciable with butyric and the higher amides. |
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JJay
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There are lots of ways to make it; most involve reacting a derivative of butyric acid with ammonia. You can make it by reacting butyryl chloride with
ammonia. I think you can also make it by reacting butyric anhydride with ammonia (or, a mixed anhydride, made, for example, by reacting butyric acid
with trifluoroacetic anhydride in cold acetonitrile and then gassing it with anhydrous ammonia).
You could probably make butyryl chloride by gassing butyric acid in acetonitrile with anhydrous hydrogen chloride. There are also numerous
chlorinating agents that I am certain would work; some of these are a little hard to obtain, but you can probably find them if you can get butyric
acid.
For all I know, you can make butyramide by refluxing ammonium butyrate in a similar manner to how acetamide is made.
Oh and the easiest way I know offhand to make propylamine would be to drop a dilute solution of propyl bromide or propyl iodide into strong solution
of aqueous ammonia with strong stirring. There are lots of other ways though.
Edit: looks like Metacelsus beat me to it.
[Edited on 12-8-2017 by JJay]
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DogWhites
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These are all certainly interesting. I really appreciate the help. This seems like a really great community here. Thank you both! Gonna dig a bit
deeper on all this stuff later as I haven't had a chance to fully check the links provided by metacelsus. I will say chlorinating agents are currently
pretty out of reach for me unfortunately  although that gassing in acetonitrile
might be a cool work around! im planning on trying to get the butyric acid from sodium butyrate supplements (apparently sold to aid in probiotic
cultivation in the gut or something) I believe the product I saw had about 600mg of the sodium salt per tablet or capsule, I think they were
reasonable price wise as well! Hopefully extraction will be easy, cuz this seems like an excellent source for OTCers. Trying to weigh my options prior
to purchasing some and trying it though. Thanks again for the help!
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DogWhites
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Hey so I'm back after having done some research and replanning. I'd like to run a few things by the forum to see if what I've come up with would be
feasible. So after the replies from you sweet sweet madmen above I decided to do some more reading. I came across a neat little mechanism called the
Hunsdiecker reaction ( https://en.wikipedia.org/wiki/Hunsdiecker_reaction ) by which the silver salts of carboxylic acids react in non polar solvent (wikipedia gives
carbon tetrachloride which may be a little hard to get in my circumstances.. maybe Et2O. MeCN, or CHCl3 would work?) with a halogen to lose CO2,
leaving an alkyl halide of one less carbon.. e.g. silver butyrate -> propyl bromide. This for me is incredible as I have quite a bit of silver
chloride stocked up from waste at my job that I could use to make the nitrate, which could again be recycled after the reaction from the corresponding
silver halide. Not to mention the relative ease of performing the reaction!
Now, sharing this information is only a small reason of why I am posting again. I would like to ask you guys your opinion/experience/guidance in
regards to the method of going from alkyl halide to primary amine via the method given above. If an alkyl halide is dropped into a concentrated NH4OH
solution, wouldn't hydrolysis of the halide to alcohol happen faster than amination? How bad are yields from this sort of procedure? Would an alkyl
iodide work best in this scenario given that I- is the best leaving group of the bunch, thus speeding up the reaction and requiring less intense
conditions to react? That is considering that the hunsdiecker reaction will work with iodine, which I have seen no mention of online. Using alcohol as
a solvent for both reagents should remove this complication, no? but in that case I would still want to use a huge excess of ammonia to alkyl halide
to avoid secondary and tertiary amines from forming. Again if I am asking too much and you think I should hit the "books" more, sending links or
references would be greatly appreciated, after all I am still relatively new to organic chemistry and may have some gaps in my self-education. Any
advice, guidance, direction, reference, admonishment, or suggestion helps. Thank you!
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