Sciencemadness Discussion Board - Phenylhydrazine sulfate from the HCl salt, first attempt

Phenylhydrazine sulfate from the HCl salt, first attempt

DrScrabs - 9-4-2019 at 07:35

Hello everyone!

So this is my frist writeup, also the first time I made pictures while doing chemistry. Please apologize any mistakes in the chemistry and feel free to correct me

Phenylhydrazine is cancerogenic, toxic(for the blood mainly) and self-igniting on contact with substrates with high surface area
Avoid contact with air as good as posssible to prevent oxidation as good as possible.

Phenylhydrazine.HCl and the sulfate salt are cancerogenic and toxic(for the blood mainly), be careful to not inhale any fine dust, protection of the respiratory system highly recommended

Potassium hydroxide is corrosive

Sulfuric acid is corrosive

Ether is highly flamable

Isopropyl alcohol is flamable

7.5g phenylhydrazine.HCl (52 mmol) are placed in a 250ml seperatory funnel and dissolved in appx 150 ml of dH2O to yield a clear, slightly yellow solution.

5g of KOH are dissolved in 20 ml dH2O and added to the seperatory funnel. The resulting solution turns to a slightly stronger yellow and is basic in ph.

The solution was extracted two times with 30ml of ether, the aliquots combined and the aqueous soln charged with 40g of KCl and shaken to dissolve the salt. On dissolving a organic layer formed and another 30 ml of ether were added on wich a red substance appeared. Most of the queous layer was removed and the seperatory funnel allowed to sit for a few minutes. Tiny bubbles on the red substance pulled some of it to te top of the organic layer. What a mess.
The ether was pipetted off as good as possible to exclude the red substance.

The combined extracts started to become more orange and were treated with a emulsion of 4g H2SO4 in 30ml of ether. A white precipitate formed immedeatly. Also unreacted H2SO4 formed a bottom layer, the ether remained yellow, ph slightly acidic.

The precipitate was then vacuum filtered and washed with with 100ml of freezing cold IPA and 50 ml of freezing cold ether. The filtrate was transfered with the filter paper on a watchglass and allowed to dry, bad idea! Upon drying it became pink and on scratching it off the paper I recognized the colour origin: the paper.
Yield: 2g (19%) crude phenylhydrazine sulfate

I have no idea why but it seems to me that the sulfate salt of phenylhydrazine is much more air sensitive than the hydrochloride. I scrached the rest of the sulfate wich was still sticking to the sides of the beaker and it had a slight pink colour, not that strong though. Also is the yield really disappointing, I will try to improve!
The sulfate will be recrystallized soon, does anybody have some solubility data?

Any suggestions what the red stuff was or any ideas how to improove are welcome. I hope the way I wrote it is ok.

DrScrabs

[Edited on 9-4-2019 by DrScrabs]

Tsjerk - 9-4-2019 at 10:33

I think the bottom water layer under the ether layer could contain quite some phenylhydrazine, maybe yields could be improved by adding less (stoichiometric?) sulfuric acid.

Apparently not all phenylhydrazine came over during the extraction, as the amount of sulfuric was about stoichiometric. Maybe using less water in the initial step is an idea. I guess the freebase is quite soluble in water.

DrScrabs - 9-4-2019 at 10:54

Yes it is quite soluble in water, I thought about salting out before the first extraction and using less water as you mentioned. In my test tube experiments i never dissolved the phenylhydrazine.HCl and I had a nice blop of phenyhydrazine floating on top on basifying.
Maybe I do change the extraction solven aswell, ethyl acetate maybe. I will report back again

For me personally it is also really important to know how the writing style is. Was it good to read? please give some feedback.

[Edited on 9-4-2019 by DrScrabs]

bipolar - 10-4-2019 at 01:10

Quote: Originally posted by DrScrabs

Maybe I do change the extraction solven aswell, ethyl acetate maybe. I will report back again

Ethyl acetate should react with phenylhydrazine, you'll get impurities of corresponding hydrazide.

Try evaporating most of the solvent after extraction, then dilute the residue with IPA and add H2SO4 (diluted with IPA) to pH ~6, i.e. no more than 0.5 eq of H2SO4 for 100% yield of sulfate salt.

And use less water in the first step if possible.

DrScrabs - 10-4-2019 at 09:13

Ethyl acetate does not react with phenylhydrazine under these conditions as stated in this paper, although it may be wrong.
The Reaction of Esters with Phenylhydrazine in the Presence of Phosphoric Acid

Maybe using less water, basify, saturate with KCl or KOH and a direct extraction with IPA. The IPA should not be miscible with a saturated salt/KOH solution. I will try in a test tube tomorrow.

I really try to use as little equipment as possible. Getting rid of hazardous waste is expensive here (2.5eur per kg)

Edit: Arghhh I can´t edit my original post anymore, so many spelling issures! Spelling kindly corrected a bit by a reddit user

[Edited on 10-4-2019 by DrScrabs]

bipolar - 10-4-2019 at 11:19

Quote: Originally posted by DrScrabs

Ethyl acetate does not react with phenylhydrazine under these conditions as stated in this paper, although it may be wrong.
The Reaction of Esters with Phenylhydrazine in the Presence of Phosphoric Acid

Maybe I'm blind, but I can't see where exactly paper says that?

Can you quote part of the paper saying that please?

Quote: Originally posted by DrScrabs

Maybe using less water, basify, saturate with KCl or KOH and a direct extraction with IPA. The IPA should not be miscible with a saturated salt/KOH solution. I will try in a test tube tomorrow.

Good thinking, but IPA will extract significant amount of inorganic compounds (especially KOH or NaOH) along with phenylhydrazine.

DrScrabs - 10-4-2019 at 12:28

EDIT for stupidity
My quotet article is in a different reaction system, I apologize. Do not take my quote as true. Esters are not always the same esters. I leave it as it was anyway.

Quote: Originally posted by bipolar

Maybe I'm blind, but I can't see where exactly paper says that?

Can you quote part of the paper saying that please?

From "The Reaction of Esters with Phenylhydrazine in the Presence of Phosphoric Acid"
BY T. 0. JONES, R. E. HALTERAN D W. L. MYERS [file attached]

"The reactions of esters with ammonia, hydroxylamine
and hydrazine to produce the corresponding
amide, hydroxamic acid or hydrazide are well
known. Cohn(2) and Meyer(3) reported a reaction
between methyl salicylate and phenylhydrazine to
produce the corresponding phenylhydrazide, and
Baidakowski, Reformatski and Slepak(4) prepared a
few phenylhydrazides by heating the ester and
phenylhydrazine in a sealed tube at 210°, but no
other examples of this reaction have since been
reported.
Various modifications and adaptations of earlier
procedures or carrying out similar reactions were
tried for the reaction using the ester and the free base in various solvents
or using the ester and the hydrochloride or sulfate
salts, all without results.
(2) G. Cohn, J. prokt. Chem., [2] 61, 548 (1900).
(3) H. Meyer, Monalsh., 98, 1383 (1907)."
(4) L. Baidakowski, S. Reformatski and I. Slepuk, J. Rusr. Phys. Chrm. Soc., 86, 61 (1902)."

The used esters are not mentioned[refering to R and R' in the pdf], we can booth be right. I´d have to synth the ethyl acetate first anyway, so I´ll forget about it at first

Quote: Originally posted by bipolar

Good thinking, but IPA will extract significant amount of inorganic compounds (especially KOH or NaOH) along with phenylhydrazine.

Thanks, good to know!
But K or Na anions do not disturb the reaction in wich I plan to use the phenylhydrazine salt, only Cl- does[IMHO] (H2SO4 cat. 4% aq; thread coming soon).
Also I plan to recrystallize the phenylhydrazine sulfate at least once to remove impurities.
Do you may have any idea for s solvent for the recrystallization of phenylhydrazine sulfate? I did not find anything on the web with my search.

Attachment: jones1953.pdf (287kB)
This file has been downloaded 403 times

[Edited on 10-4-2019 by DrScrabs]

bipolar - 12-4-2019 at 06:36

Quote: Originally posted by DrScrabs

But K or Na anions do not disturb the reaction in wich I plan to use the phenylhydrazine salt, only Cl- does[IMHO] (H2SO4 cat. 4% aq; thread coming soon).

It's just you won't be able to calculate the yield of phenylhydrazine sulfate.

Quote: Originally posted by DrScrabs

Also I plan to recrystallize the phenylhydrazine sulfate at least once to remove impurities.

I think that in this case recrystallization is unnecessary if your starting phenylhydrazine hydrochloride was decently pure.

Tsjerk - 12-4-2019 at 07:23

Can't you titrate the hydrazine after the proposed IPA extraction? If it produces superior purity it might be worth the effort.

UC235 - 12-4-2019 at 19:36

What procedure would this possibly matter for? The only immediate use I know for phenylhydrazine is indole synthesis, which can use HCl in ethanol as catalyst, and so is certainly insensitive to Cl-

DrScrabs - 16-4-2019 at 04:30

Quote: Originally posted by Tsjerk

Can't you titrate the hydrazine after the proposed IPA extraction? If it produces superior purity it might be worth the effort.

If you mean after neutralization?
I you know a good method exept for potentiometric titration please let me know

If you mean before then I would work under N2 for accurate results. I´ll think about it.

Quote: Originally posted by UC235

What procedure would this possibly matter for? The only immediate use I know for phenylhydrazine is indole synthesis, which can use HCl in ethanol as catalyst, and so is certainly insensitive to Cl-

It will be used in a Fischer indole synthesis. The paper I am following states aq HCl gives more impurities and lower yield and I found an example for an interrupted fischer indole synth with Cl- in "Indole Ring Synthesis, Gordon W. Gribble, 2016, p42", scheme 2.
Also if I do the calculation and assume sulfate salt formation is dominat a maximum of 37% of the H2SO4 catalyst is consumed by the ammonia and the product. The ratio of H2SO4 to HCl would be somwhere in between and this is not really what I like..
The thread on the synth is coming these days anyway, with the HCl salt though (maybe I can post with the sulfate also if I do get enough pure salt

Tsjerk - 16-4-2019 at 07:25

Quote: Originally posted by DrScrabs

Quote: Originally posted by Tsjerk

Can't you titrate the hydrazine after the proposed IPA extraction? If it produces superior purity it might be worth the effort.

If you mean after neutralization?
I you know a good method exept for potentiometric titration please let me know

If you mean before then I would work under N2 for accurate results. I´ll think about it.

Yes, I mean after neutralization. I don't think it would contain much else than the sulfate salt, but if you really need to know what percentage it is you could titrate. I will have a look at how that would be possible.

DrScrabs - 16-4-2019 at 11:09

Quote: Originally posted by Tsjerk

Thanks!
I have still some Ph-hydrazine left and I will try try the IPA extraction tomorrow or thursday, test tubes looked promising but I didn´t try to form a precipitate yet. Then it´s just about finding a good solvent for the recrystalization, thinking about water/alcohol solvent mixture, maybe pure alcohol works anyway

DrScrabs - 25-4-2019 at 14:16

So I have still not managed to try the extraction with IPA with precipitation of the sulfate, but I stumbled about a crystallization of phenylhydrazine from alkanes, maybe extraction with naphta, drying with MgSO4 and then collect the crystals (in N2 atmosphere?).
Faraday got really pure benzene by crystallization back in his days!