Author Topic: probs after LAH/p2np  (Read 1936 times)

0 Members and 1 Guest are viewing this topic.

dextro

  • Guest
probs after LAH/p2np
« on: October 15, 2004, 08:15:00 AM »
hi,
swim made a LAH (14,5g) reaction with P2NP (20g) in THF...

- refluxed 6 h
- quenched
- distilled off the THF in vacu
- yellowish residue with fishy smell received

and this is the point where the disaster starts:

- poured 200ml water to this residue gave me a nice 
  golden layer on top of milky water
- this was actived with HCL to pH 1
- washed 3 x with DCM, which removed most of the yellow 
  colour
- made basic with NaOH to pH 12-13 and at this point it  
  seems to be that the FB was the bottom layer, hm?
- anyway, the FB was extracted with DCM. after evaporation
  of the dried DCM, a light yellowish residue with 
  fishy smell received.
- made the salt of this with H2SO4 in ether/ethanol

BUT THIS WAS SHIT AT ITS BEST (no effects, no fun....)


swim made several LAH reactions before and the result was O.K. everytime (tried not to perform an A/B to make purer product).

but today swim tried to make better product, so he decided to make this fucking A/B.
can/t understand where the mistake is, also can`t understand why the FB before the AB is ON TOP of the water and after the A/B it was on the bottom of the water????

is it nescessary to do this a/b ? why not dissolve the risidue (after DCM evap.) in ether, drop in diluted H2SO4 and filter off the salt?

hope there is somebody out there, need help

thx

indole_amine

  • Guest
everything is normal
« Reply #1 on: October 15, 2004, 07:51:00 PM »
If you basify an aequous amine solution saturated with DCM, all amine oil immediately dissolves in the tiny DCM drops, and sinks to the bottom, together with the DCM.

You can avoid this ( if you want) by washing out the DCM traces with your preferred top-puller (maybe toluene? ..ether?) BEFORE basifying - and the oil will separate to the top...


Your reaction and workup were perfect.
It appears like you are just missing the buzz of impurities! Take more of your clean stuff, and then report back... :P


indole_amine

dextro

  • Guest
thx, for your reply !
« Reply #2 on: October 15, 2004, 10:22:00 PM »
thx, for your reply !

next attempt is done with 12 hours rxn time.
resulted a much more yellow colored THF solution :)
and quenching rxn was done with much more NaOH.

the yellow residue is splitted now:
50% was worked up without A/B and the final salt was tested by nose: numbness in my throat near as cocaine,
never had this before.
other feeling is typ. also. success everywhere.... 

other 50% were workedup with aditional A/B, but is not ready now. write more later....

best regards

Bandil

  • Guest
"missing the buzz of impurities"
« Reply #3 on: October 16, 2004, 12:17:00 AM »
Argh, missing the buzz of impurities. Come on, you should know better than to advocate actually striving for impure compounds.

Pure amphetamine sulfate is not very potent "per volume" so to speak. If you are used to taking meth.HCl youll need to do heaps more to get anywhere near comparable effects.

I have a really hard time seing that you should have wrecked the synthesis here. Unless you make a major lab fire with LAH, the reductions involving this rarely go wrong.

So save that amphetamine please. It's much more mellow and less fun than meth, but it gets the job done never the less  ;)

Have a nice weekend, regards
Bandil


indole_amine

  • Guest
yes
« Reply #4 on: October 16, 2004, 06:06:00 AM »
Erhm - actually I just tried to say the same thing!  :)

(meaning that with the rxn and workup he described, the product is far more likely VERY pure, and due to the lack of tweaker impurities he doesn't recognize it anymore)

So, for clarification: Impurities are a bad thing, and saying "your product is even purer than what you've ever seen before!" is a hidden compliment - isn't it?


indole_amine

icexool

  • Guest
Is this also counting for 2C-B when using LAH?
« Reply #5 on: October 20, 2004, 12:25:00 PM »
Is this also counting for 2C-B when using LAH?
Because in the synthese on rhodium.ws they use 15% NaOH solution, with an amine...

indole_amine

  • Guest
NaOH? Surely not for reduction...
« Reply #6 on: October 21, 2004, 04:42:00 AM »
Surely not for the reduction of the nitrostyrene. You probably meant the Henry/Knoevenagel condensation with a base catalyst (which can be an amine or inorganic base)?

To make 2C-B from, lets say, (2,5-dimethoxy-4-bromophenyl)-2-nitroethene, you just have to react it with LAH in a suitable anhydrous solvent (diethyl ether, better THF). You then saturate the C=C bond to C-C and reduce the NO2 group to an NH2 amine group.

Instead, you could of course use the Leminger reaction (Zn/HCl) to achieve the same...

(UTFSE)


indole_amine