## RFC: Proposed nitro -> amine reduction for general use

### by Eleusis

Recently, there has been some interest in my e-mail about making nitrostyrene intermediates. This is no doubt related to ZWITTERION's recent posting on it. He has also asked me to research various alternatives to LAH in the reduction of the -NO2 to a -NH2. This seems to be an excellent and worthy pursuit since LAH is not only hard to come by a but a bit difficult to work with. Here's a representative example, I request that if you do try this with any particular nitro compounds that you send me the results, anonymously, and I will compile the data into a FAQ. re: PiHKAL #16 In this synthesis, Shulgin reduces a nitro terminated, secondary methoxy chain to a beta-ethanolamine. The reduction is strong enough to convert the chain methoxy substituent to an alcohol, but does not affect the ring methoxys (due to resonance stabilisation from the ring). This naturally leads me to believe that the Zinc/Hydrochloric acid reduction would be viable for the reduction of straight nitro terminated chains to amines as well, a task which Shulgin normally assigns to LAH. ZWITTERION has specifically asked me for information pertaining to the production of 2C-B, but I do not the raw materials to test that exact compound, and even though 2C-H (the precursor phenethylamine to 2C-B) is not controlled, I'd rather not have it sitting around anyways... so, here is the proposed Zinc/Hydrochloric Acid reduction process for general purpose nitro use. ### Cognate Procedure .16 moles (34g in the case of the 2C-B intermediate) of nitro compound are dissolved in 300mL glacial acetic acid in a 500mL flask (erlenmeyer seems ideal for this). A stirrer bar is added, stirring commenced, and slowly, 100g of powdered Zinc is added, along with additional glacial Acetic Acid as necessary to maintain a smooth solution. This is allowed to homogenize thoroughly (between 15 minutes to 1 hour) while heating to 100°C on a boiling water bath. Then 100mL of concentrated Hydrochloric Acid (115 mL "muriatic acid") is added *slowly* enough to prevent explosive bubbling. Once all the acid is added, heat for an additional 15 minutes. Now pour The reaction contents into 2L of cold distilled water. Wash this solution with 2x100mL methylene chloride (save for redistillation). Then basify to pH 12 with 25% NaOH (w/w, or, 15g NaOH to + 75mL water) CAREFULLY with vigorous swirling. Allow the solution to sit for several minutes once pH has risen above 10 - it has been my experience that the pH drops appreciably when sitting. Once pH has stabilized to between 11.5 and 12.5, it is time to extract out the amine. I will assume the use of a 500mL sep funnel, as a 2L one is hard to come by and harder to afford - besides, it's a little too big for me to feel comfortable shaking ;-). Pour 400mL of the amine/water suspension into the funnel, then add 50mL methylene chloride and shake with a vigorous circular motion. Don't forget to bleed the pressure off, and hold onto that stopper. Repeat with 25mL of methylene chloride. The CH2Cl2 layer should be on bottom. Repeat the entire process 4 more times. You should then have approximately 375mL of methylene chloride with the amine dissolved in it. Assemble a conventional ground glass distillation setup with vaccum receiver adapter. Strip the solvent off with gentle heat (bp: 41°C) and recover for reuse. Pour off the recovered methylene chloride, then connect a vacuum pump to the distillation apparatus and pump down to about 50 torr to strip the remaining solvent and water. Rinse the receiving flask with acetone, allow to dry, then pump the system down as low as you can manage it. NOTE: 40 torr is the maximum acceptable pressure for distilling the phenthylamines, and this is generally within the realm of a positive pressure design water pump powered water aspirator (ie - not a centrifugal type water pump, but a closed cavity design). An oil immersion vacuum pump is superior for this type of work and well worth the investment. After the vacuum gauge reads below 40mm Hg (or 720mm if it's "backwards"), turn on the heat and distill the amine freebase. Most of interest will come over between 140 and 180°C at typical vacuums in the tens of torr. Protect the freebase oil from the atmosphere, or, use within 2 hours MAXIMUM. Most amines like this will polymerize extremely well, and I suspect no one here is interested in making new wrapping materials or carpet fibers. FINAL NOTE: Remember, this is untested. Don't bitch at me if it doesn't work, it only THEORETICALLY should. ZWITTERION promises me he'll test it, but I'd like to hear from more of you than just him. Good luck.

- eleusis@netcom.com - Proposed nitro -> amine reduction -