TMA-2, final steps..yep, question

[Daphuk_up]

SWID recently reacted 1-(2,4,5-Trimethoxy)phenyl-2-nitrostyrene(3.5g) with in situ generated PBI.

This was extracted and cleaned as described in the reference article.  Everything looked good, or so SWID thinks, and the crude resin was taken up in methanol (75ml).  To this was added 3g Zn dust, with stirring, followed by 3ml of saturated ammonium formate aqueous solution.  The reaction mixture got hot and needed a cool water bath to calm it down.  As soon as it relaxed a bit, it was taken from the bath and allowed to stir for ~20min.  The Zn was filtered off, and the resulting transparent solution was a reddish color.

The methanol was distilled off, at which point there appeared to be a significant layer of water left in the flask.  This was stripped under vacuum until only solids remained.

Diethyl ether was added, but this didnt solvate anything in the flask well, so it was distilled off.  Anhydrous 2-propanol was added, and the result was a deep red liquid, and a tannish precipitate.

SWID has pre-HCl-gassed anhyd. IPA ready to go.  The question is, should he filter off the tan precipitate?  Could that possible be TMA-2*formate?

Any suggestions would be greatly appreciated.  SWID has attempted a reduction of the nitrostyrene so many times and failed, he would really like some advice before proceeding.  Thanks so much.

[retarded]

you don't have to discard any filterings.

[Daphuk_up]

An excellent point.  Your reply also provided SWID with the courage to go on.

The solution was filtered, the tan material set aside to dry.  The filtered solution was then titrated slowly with IPA sat. with HCl.  To SWIDs utter amazement, on about the third addition, crystals began to form!   He titrated a bit more, getting more of the hair-like fine crystals precipitating, and watching the pH closely.  Although the pH didn't go down, he decided to stop titrating on an instinctive urge, and stuck the flask into the freezer.  Time to wait.  After filtration, he can always titrate more, and he is afraid that if the pH hits a certain amount, all that blood red (ketone?  nitrostyrene?) some-kind-of-asarone-derivitive will polymerize into inextractable crap.

Anybody got a clue what this tan material is?  Looks like quite a few grams...some kind of zinc complex or something?

(2 hours later)

Well, after sticking it in the fridge, more crap precipitated...this time after filtering, the stuff on the filter is a dark chocolate brown.  The mixture was titrated again, with the formation of more crystals, and after a while these were filtered and washed with fresh anhyd. IPA.  Nice white crystals on the watch glass.  SWID went to titrate again (it was taking forever), and since he was almost out of his pre-gassed IPA, he picked up the flask to pour the last in.  Then, then he noticed it.  The bottom of the fucking flask (that contained the gassed IPA) was covered in fine, hair-like crystals.  SWID isn't sure what the hell he has been desperately trying to save, but is reasonable sure it isn't TMA-2.  No, the dropper which was used to transfer liquid from one flask to the other never touched the supposed TMA containing liquid.  It makes no damn sense.  The pre-gassed IPA was created by seperating it with table salt, then drying over baked magnesium sulfate, then bubbling dry hydrogen chloride gas in.  (Made by the action of sulfuric on muriatic-wetted sodium chloride, and passed through a 500mL flask filled with calcium chloride.)

(Half an hour later)
The tan material is nearly completely dry (dry to the touch, still a slight hint smell of IPA).  It weighs 4g currently.  It is a very powdery substance, and SWID recently noticed that it "sparkles" when wobbled around (at angles to a light that would produce refractions, if that makes any damn sense.)  Could this maybe, just possibly be very impure TMA-2?  The second filter, the dark chocolate colored one, is also almost dry, but has turned into some nastly looking tar-like substance.

SWID supposes the only proper test for the tan substance would to be to put it through an acid-base extraction.

Suggestions are always appreciated.

EDIT: burn-test on aluminum foil.  The tan precipitate didnt burn clean, but it did vaporize, leaving a black spot.  The crystals from the HCl+IPA flask are clearly an inorganic salt, remaining almost unchanged on aluminum foil with a butane flame underneath.

[starlight]

If the 2,4,5-Trimethoxyphenyl-2-nitropropane you put into the zn/formate system is as impure as you describe, I would be surprised if you get anything useful out of it. The HCl salt of this amine is hard to precipitate when impure.

[Daphuk_up]

SWID took the flask with the IPA solution in it, added about 10 drops of concetrated sulfuric, and threw it in the freezer overnight.  While this was chilling, the tan material was mixed thoroughly in 150mL of dH20, and perhaps maybe a third of it actually dissolved, forming a yellow fluid and a darker brown precipitate.  Next, 50mL of hexane were added, the solution basified to pH 11, and the aqueous solution was extracted 2 more times with 20mL each of hexane.

The hexane (Which had a slight yellow-pink tinge) was washed with 25mL NaOH, 25mL NaCl, and 25mL of dH20.  It was then dried over freshly baked magnesium sulfate (half teaspoon placed directly in liquid). After allowing to dry for approximately two hours (with stirring), The sulfate salt was filtered off.  Into the hexane in a new clean flask was dropped 6 drops of concentrated sulfuric acid.  This was thrown in the freezer as well.

The next day the first flask with the original IPA solution was removed, and a large volume of brown-to-tan precipitate was filtered off, and will be put through the same extraction as detailed above, after it has been thoroughly dried.

The second flask with the hexane solution has a small <1mL amount of an amber colored oily precipitate.  SWID is unsure if this is just some sort of sulfuric acid-hexane mix, or if a small quantity of TMA-2*sulfate has oiled out.

[Daphuk_up]

The brown to tan precipitate was put throught the same extraction and clean up as detailed above.  Left overnight in the freezer, the next morning some oily subtance very similiar to that in the other flask has precipitated out, but in a larger volume (maybe 1-2mL).

The hexane will be poured off, and the oily liquid taken up in the smallest amount of dH20 possible, balanced to pH7 with sodium bicarbonate, and about one third of the water will be evaporated off.  Once the resulting solution has cooled to ~60C, 50mL of freezer cold acetone will be dumped in.

SWID is sure of one thing...whether this works or not, his next project is going to be something that doesn't involve asarone.  His methods are just too amaturish and crude for such a sensitive molecule.

[Vitus_Verdegast]

If you can obtain some NaBH₄, then making TMA-2 from asarone is quite simple. The pseudonitrosite reaction is the only yield limiting step in my experience, it gave between 5 - 8 gr 2,4,5-TMP2NP per run of 20 gr asarone.

Reducing this with borohydride in IPA is really easy and always gave almost quantitative yields of the substituted nitropropane as white crystals. These were reduced in decent yield with activated Zn + HCOOH.

If you really long to prepare some TMA-2, using cheap and easily obtainable reagents, I recommend you to try this route.

[Daphuk_up]

If NaBH4 was an option, SWID definetly wouldn't be messing with PBI.  Unfortunately, its watched and unavailable where SWID lives.  SWID strives for 100% OTC-ness, which would be considered an 'achieved' goal if he could produce some frontal lobe candy.  Hopefully, he will succeed eventually.  Also, SWID thinks its more his technique than the reagents available that causes failure.  He still just has a lot to learn, even after a year and a half of intensive study.