I've made the melting point and it's a bit depressed, 132-135 instead of the 138-139 C of PIHKAL. The product is not absolutely white, but a bit tany, so I hope that the reason for it is that a quick and not too much cared work-up have carried some impurities. I wanted to see the end as soon as possible !!!
We'll try a 30 grams batch trying to optimize the Zn (I think 3/4 parts it's enough) and work-up, and I'll post it.
Theoretically it should work for any nitrostyrenes or even nitropropenes (what about 2,4,5 TMP2NP ?, isn't it sensitive to acids ?). And it will be fine for low dose compunds, but for mescaline for example, just to get a few doses.
This is the reference, posted by Antoncho after Rhodium's inquiry, if I remeber correctly:
Antoncho
(Newbee)
04-23-01 07:56
No 186076
Re: References on nitrostyrene reduction
OK, here's what it says:
As was already mentioned, it only deals with the compounds in which either R1 or R2 or both of them are hydrogens. Unclear yet if it will make any differense.
The rxn is made with Zn powder in aqueous acid soln with heating. The conc. of acid should be 4-22%. Best choice for acids are acetic or formic, in presence of EtOH or THF. These conditions allow for increasing the yield by 19-28% - up to 76% and no HgCl2 is required.
Example 1. To the suspension of 0,627 g of 2,4-dimethoxyPEA in 18 ml H2O there's added 3 ml 36% HCl and, with effective stirring, maintaining the temp at 25-30 C, over the course of 4 hours tere is added in small portions so as not to allow excessive foaming, 7.1 g of Zn dust and 27 ml 36% HCl... stirring is maintained for 1 more h, utill all Zn is dissolved. After that the rxn mixtr is a clear, colorless soln without any solid particles. Washed w/ 2x 10 ml benzene, aqueous phase is basified with approx 90 ml 25% NaOH with stirring and cooling, so as not to allow the temp rise over 30 C; until all initially formed Zn(OH)2 redissolves. The product which is an oily subst. at this point is extr'd w/4x30 ml benzene, washed w/10 ml 2% NaOH, dried for 12 h w/ 6 g KOH, quickly (to avoid forming any carbonate) thru a dense glass filter and evap. the solvent. After drying to const weight the yield is 0.534 g. (98%)
Example 2: 3,4-dimethoxyPEA. 1,045 g of the nitrostyrene w/ 3.27 g Zn (10x molar excess) are ground into fine powder, suspended in 9 ml H2O, cooled to 5 C, over the course of 0,5 h 27 ml 15 HCl are added with stirrng and cooling (temp <10-15 C) Stirred for 0.5 h more at 10 C, then 31 ml 36% HCl is added (0,5 h, 10-15 C), not allowing strong foaming. Temp then allowed to rise to 25-30 C while adding 3,27 g Zn dust and 20 ml 36% HCl for 0,5 h. Stirred for 1 more h until all Zn dissolves. The rest like above, xept drying agent 15 gNa2SO4+ 2 g KOH (time not specified) Product's a yellowish oil that on standing crystall. to almost colorless crystals. Yield 0,819 g (90,5%)
Example 3. All like in #2 xept 4-metoxyPEA, yield 88%
Example 4. 4-methoxyPEA. 0.537 g nitrostyrene, 11.4 ml formic acid, 2 ml 36% HCl at 10-15 C; added 2.03 g Zn, 8 ml HCl, 5 ml formic (for 0.5 h) Stirred for 45 more min. Added for 15 min at 20-25 C 0.77 g Zn, 6 ml HCl, 3 ml formic. The rest as above (Note: when basifying, temp never allowed to exceed 30 C). Yield 87% Formic acid was employed merely to reduce the amount of foam during the rxn.
Example 5. 4-methoxyPEA. 0.537 g nitrostyrene, 9 ml acetic, 7.5 ml 36%HCl. Temp 25-30 C, for 0,5 h added 2.07 g Zn. Then added 1.5 ml HCl and stirred for 1 more h. Then extracted as above(xcept the first benzene wash is washed twice w/5% HCl and then aq. liquors combined). Yield 79%
Example 6. 4-benzyloxy,3-methoxyPEA. All as in #5. Yield 82%
Example 7. 4-PropoxyPEA. To the mixture of 15 ml EtOH, 15 ml 36%HCl w/stirring at temp 25-30 for 20 min is added finely ground mixtr of 1.035 g nitrostyrene and 1.31 g Zn (4x molar excess) During the next 15 min added are in small portions 1.66g Zn and 5 ml HCl. Stirred 55 min until all dissolved. Extraction like in #5. Yield 84%.
Example 8. 4-ethoxyPEA. All like in previous, xept THF as the solvent. Yield 88%
Example 9. 3,4-dimethoxyPEA 1.45 g styrene as fine powder susp in 16 ml aqua, then 4 ml
HCl added, then over 40 min at 25-30 C added 26 ml HCl, 3.98 g Zn, stir till all dissolves. Extr like in #1 Yield 91.5%
Example #10 3,4-DMPEA. 1,045 g powdered styrene susp in 15 ml aqua ; added 3 ml HCl. Then w/stirring over 1 h at 25-30 added 12 ml 26(?)% HCl and 2.215 g Zn. Stirring 2 h till all dissolves. Extr like in #1 Yield 90%
Examples #11 and 12 are relatively useless and used to define the optimal conc-tion of acid, which appears to be around 15 percent. The paper repeatedly emphasized that acid conc. should be between 4 and 22%.
Whoo... I finally did it. Any questions on the details of the transcription are welcome. HCl conc. is 36% where not specified otherwise.
Sweet Jesus! Now, i wonder if everything is really THAT easy. Although there has been lots of published here trials using approx the same method, i believe, this exact combination of conditions (keeping the temp and acid conc low ) was never experimented. Can't be confident with that, though. ...man... Just Zn and HCl in good old H2O... Doesn't look believable, but it's a patent, after all!
I just looked it up in PiHKAL, 3,4-DMPEA. The corresponding nitrostyrene is reduced w/LAH for 18h and it yields 3.3 g from 11.45 g ! Looks like this one is not particularly easy to reduce, huh? The 3-ethoxy,4-methoxy- yields 3.8 g from 6.2 g - not the best of yields, too. Looks like the stuff described in this patent is none easier to reduce than the "conventional" nitrostyrenes. I don't know shit about materies like that. Can anyone comment? Is there a way to tell?