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Author: Subject: Hydrazine
S.C. Wack
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[*] posted on 9-2-2022 at 14:44


BTW none of that applies to Name Brand 7.5% hypochlorite.

Now 90% of all the bleach bottles in the store are "low splash" and/or scented. Perhaps the remainder on the bottom shelf are old stock which will be replaced with the modern, advanced, state of the art (i.e. shit) merchandise that everyone is clamoring for (how many times a day do you hear people complain about bleach not being syrupy).

"Cloromax technology" (no, really) results in the Mn not decolorizing or precipitating, a persistent haze, and a different precipitation of the sulfate. Perhaps this bleach has the same additive as the "low splash" product, just less of it. When combined with Dr. Thönnessen's amounts above, the yield is 61%, and the product is inferior to the cheap hypochlorite sulfate.

Repeating without any additive (other than Thönnessen's 50% excess of NaOH and whatever secret ingredient is in the bleach) gave a clear colorless liquid in which the haze did not appear until at the neutral point. This time, the magnetic stirring was continued as the conc. portion of the acid was slowly added dropwise. The resulting first crop sulfate was the dull uniform fine powder of earlier stirring trials, yet this material was of quite good purity. Unfortunately, 22% of the total was in the second crop, which had much more Na (and no organic residue) in it. There was none of the gas which always evolved from the sulfate in contact with the mother liquor when using Mn. 64.6%.

Sodium bisulfate would have been tested if I or the stores had the prill in stock.




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S.C. Wack
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[*] posted on 17-3-2022 at 15:59


Lobry de Bruyn wrote in 1895-6 of adding barium chloride to hydrazine sulfate to form the dihydrochloride (insoluble in methanol), which is heated to form the monohydrochloride, which is dissolved in methanol and basified with sodium methoxide, or barium bromide is added to the sulfate, followed by KOH with the KBr precipitating with alcohol, or the sulfate is basified with KOH or NaOH, and the alkali sulfate is precipitated with alcohol. (Adams and Marvel write in 1921 that this last method gives 50% hydrate in 50-60% yield after vacuum distillation) He also makes anhydrous hydrazine from the "hydrate" with BaO.

Given all of that, it's striking that the professor did not mention basifying in part with barium hydroxide and in part with NaOH, followed by precipitation of sodium sulfate with alcohol.

Most posters here seem to prefer NaOH at both stages, with a lot of salt at the end. Going for less salt, I converted hydrazine sulfate to dihydrazine sulfate by adding barium hydroxide (112% of the theoretical weight of freshly recrystallized, vacuum filtered, undried octahydrate) to a pH around 4.4, obviously in hot solution followed by some workup. An interesting optical phenomenon was noted during the magnetic stirring of barium sulfate in dihydrazine sulfate (with fluorescent tube light): the center of the vortex was blue. The barium sulfate was washed more by decantation than filtering.

Distillation of the water was stopped at the theoretical weight of 50% concentration, and 105% of the theoretical amount of 50% NaOH was added. Less than 62% of the expected weight of sodium sulfate was collected by vacuum filtration. Instead of precipitating the rest with methanol, distilling it off, and vacuum distilling the remaining volatiles, the filtrate was distilled with aspirator vacuum. This distillate was found to be 17.3% hydrazine (27% hydrazine hydrate), in 81% yield, by titration with iodate.

This concentration could have been higher if the dihydrazine solution had been properly analyzed, because it could have been boiled down further with less NaOH added. It's unclear at which stage the missing hydrazine was lost, due to this overall sloppiness. The last portion of hydrazine to come over was of presumably high concentration (oily drops in the receiver), so it's not unlikely that some was lost in the apparatus and residual hydroxide and sulfate.

So, the whole process has to be repeated with more care, and this is in progress. What I was really interested in was this last part: the distillate was concentrated in a desiccator with lime. If the initial daily water loss held steady, it would be hydrazine hydrate at 15 days and anhydrous hydrazine at 21 days, this was however not the case, and the loss slowed some, even with fresh lime. Titration today indicates exactly 25% hydrazine w/v.

There were plans to take this further before posting, but I made the mistake of mentioning this in a thread where I argued with an admin, who just hours later totally by coincidence announces his intention to lock this thread, and immediately this thread magically became the frontrunner in voting to be the very first of all threads locked. (a lot of people spent a lot of time writing posts in this thread, just for it to be locked and unstuck, and for their posts to be reduced to a much more important "summary" written by someone else, if mentioned at all...so why bother writing anything in the first place?)




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[*] posted on 23-3-2022 at 05:03


Tried the urea + bleach + MEK method on a half-molar scale with 750ml of 5% bleach ...

After the solution is cooled for an hour or so (it retains heat really really well!), MEK is added and stirred for about 3-4 hours.
Unlike what Doug's Lab said, my mixture didn't become cloudy, clear, then cloudy again (ketone -> hydrazone -> ketazine?); it stayed cloudy (and warm!) throughout.

Organic layer on top is separated, and 36% sulfuric acid is added.
White flaky ppt is formed almost immediately. An organic layer (MEK+ketazine?) floats on top of the aqueous/sulfuric acid layer (red line) ...

Will continue tmr and do a decantation/filtration to get an initial batch of hydrazine sulfate, then do a distillation with the filtrate to remove the MEK/water to get a second batch, fingers crossed.

What can I use to wash the hydrazine sulfate after filtration?

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[*] posted on 30-3-2022 at 00:41


Hydrazine has the chemical formula N2H4 and is an inorganic substance. It is a colorless flammable liquid with an ammonia-like scent that is a simple pnictogen hydride. Hydrazine is extremely hazardous unless it is handled in solution, such as hydrazine hydrate (NH2NH2 xH2O). The global hydrazine hydrate market was worth $350 million in 2015. Hydrazine is primarily employed as a foaming agent in the preparation of polymer foams, but it is also utilized as a precursor to polymerization catalysts, medicines, and agrochemicals, and as a long-term storable propellant for in-space spacecraft propulsion. In 2015, around two million tonnes of hydrazine hydrate were used in foam blowing agents. In addition, hydrazine is employed in the preparation of gas precursors used in airbags, as well as in other rocket fuels. Hydrazine is utilized as an oxygen scavenger in both nuclear and conventional electrical power plant steam cycles to manage dissolved oxygen concentrations in an effort to minimize corrosion. Hydrazines are a type of organic compounds formed by substituting an organic group with one or more hydrogen atoms in hydrazine.
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[*] posted on 26-7-2022 at 01:23


Nickel and cobalt hydrazine nitrates. Cobalt is a much better explosive material than nickel, but also unstable. two days later it became very weak because of decomposition.

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[*] posted on 15-10-2022 at 16:45


I made hydrazinium hydrogensulfate using 250 ml of 12.5% pool shock(actually 10%). I mostly followed NileRed's procedure except I used HCl to neutralize sodium carbonate. My final yield was 26g. I'm going to do a titration to make sure it's not half sodium sulfate.:)

[Edited on 16-10-2022 by Sir_Gawain]
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[*] posted on 15-10-2022 at 23:06


Is there any reason why sulphuric acid is preferred over hydrochloric acid in the neutralisation of hydrated hydrazine? Couldn't both be used?
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[*] posted on 16-10-2022 at 12:06


Hydrazine hydrogenchloride is about 10 times more soluble than hydrazine hydrogensulfate. Hydrochloric acid is sometimes used to neutralize the sodium hydroxide and carbonate, then sulfuric acid to precipitate hydrazine hydrogensulfate. Sulfuric acid can be used for both (as NileRed did), but sodium sulfate has a low solubility at low temperatures and can precipitate out and contaminate your product.

[Edited on 16-10-2022 by Sir_Gawain]

[Edited on 17-10-2022 by Sir_Gawain]

[Edited on 17-10-2022 by Sir_Gawain]
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[*] posted on 16-10-2022 at 22:33


Quote: Originally posted by Sir_Gawain  
Sulfuric acid can be used for both (as NileRed did), but sodium sulfate has a low solubility at low temperatures and can precipitate out and contaminate your product.


Yeah, I saw that in hindsight, and came upon a recipe clearly stating that filtering hydrazine hydrosulphate should not be done below 25 °C to limit sodium sulphate contamination.

That being said, is it possible to use sodium bisulphate instead of sulphuric acid?
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[*] posted on 17-10-2022 at 10:09


You could try it but I don't think that would work. Even if it would, it would add a massive amount of sodium sulfate that would likely precipitate out with your hydrazine hydrogensulfate. To neutralize 32g hydrazine you would need 240g NaHSO4. 2NaHSO4 + N2H4 = Na2SO4 + N2H5(HSO4) This would produce 140g of sodium sulfate and only 130g of hydrazine hydrogensulfate.

[Edited on 17-10-2022 by Sir_Gawain]
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[*] posted on 17-10-2022 at 10:21


Quote: Originally posted by Sir_Gawain  
You could try it but I don't think that would work. Even if it would, it would add a massive amount of sodium sulfate that would likely precipitate out with your hydrazine hydrogensulfate.


Solubility of sodium sulphate at 25 °C seems to be one order of magnitude higher than that of hydrazine sulphate.
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[*] posted on 17-10-2022 at 10:57


It might work if you use hydrochloric acid to neutralize the sodium carbonate, then sodium bisulfate to precipitate hydrazine hydrogensulfate. If you use sodium bisulfate for both steps there would be too much sodium sulfate produced. Try it and report back. If it does work it would be great for people who can't get sulfuric acid.

[Edited on 17-10-2022 by Sir_Gawain]
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[*] posted on 17-10-2022 at 22:39


Quote: Originally posted by Sir_Gawain  
… If it does work it would be great for people who can't get sulfuric acid.

[Edited on 17-10-2022 by Sir_Gawain]


Will do.
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