Sciencemadness Discussion Board

Failed Methylethyl ketazine synthesis

AirCowPeaCock - 10-1-2012 at 07:33

I attempted a methyl-ethyl ketazine synthesis based on nurdrage's instructions, I used a 4% solution of NH4OH though. Added the sodium hypo-chlorite by burette (6%) to the MEK Ammonium hydroxide solution over 2 or so hours. All was done under an ice-bath. Set the beaker covered aside overnight. The next morning a layer of what appeared to be the ketazine was floating on top, thin but definitely there. The fluid was still cloudy so I gave it another few hours. When I returned the layer was gone and the solution turned a bright pink orange. The solution smelt strongly of MEK when I poured it out. What went wrong? Why the color change? I'm going to attempt again today with a 20% solution NH4OH--was the concentration the problem?

mr.crow - 10-1-2012 at 08:00

Definitely the concentration. Also stoichiometry, there was probably way too much bleach/NaOH which hydrolized the product

AirCowPeaCock - 10-1-2012 at 08:30

I did have a little excess bleach, but certainly not way to much.. But what compound was pink? sodium salt of MEK? Does that even exist? Partially oxidized MEK?--From extra Chloramine, or just extra bleach?

AirCowPeaCock - 10-1-2012 at 08:47

Hows this:
166.7 g 6% NaClO sol. added by burret over 2 hrs to
92 g 20% NH4OH sol. mixed with
19.4 g MEK?

stiring the whole time

[Edited on 1-10-2012 by AirCowPeaCock]

UnintentionalChaos - 10-1-2012 at 09:18

Orange color is gunk from base catalyzed aldol condensations of the MEK

AirCowPeaCock - 10-1-2012 at 09:55

Ok, Thank you

aaparatuss - 10-1-2012 at 17:24

I hope things work out for you this go round, but if you had 20% ammonia available what where you hoping to accomplish by using 4% concentration?

Im still working out the equilibrium but I was wondering if adding urea to a weaker ammonia solution will enhance chloramine formation and hence ketazine formation.

The point being 10% ammonia solution is what is available.


goodluck

AirCowPeaCock - 10-1-2012 at 18:30

4% was what was avalible off the shelf.. im making some 20-30%(hopefully) as we speak. Its looking good!(:

mr.crow - 11-1-2012 at 07:45

You can use Urea instead, check out UC235's excellent video on youtube

AirCowPeaCock - 11-1-2012 at 08:24

I heard you get alot more by products with that method. Have experience with it?

UnintentionalChaos - 11-1-2012 at 10:28

I extract the crude hydrazine by formation of the butananone azine, precluding NaCl contamination. It certainly worked fine for making luminol.

http://youtu.be/JCrDttuw5co
http://youtu.be/URIAB32Q_JQ

AirCowPeaCock - 11-1-2012 at 11:29

I think I'm going to stick to the hypochlorate-ketazine process NurdRage mentions, if it doesn't work with the concentrated reagents, Ill try yours. But after the Luminol synthesis I'll do with Urea just for fun, Maybe Ill use the Hydrazine.Sulfate to produce pure Hydrazine (solvated in water)--I'll see what I can do about inert atmosphere distillation. So I can say I got that rocket fuel from my piss! ;)

aaparatuss - 11-1-2012 at 16:58

http://books.google.com/books?id=VqosZeMjNjEC&pg=PR8&...

chapter 11 of this google book
Small-Scale Synthesis of Laboratory Reagents with Reaction Modeling

has pretty nice work up for alcoholic hydrazine. I would almost buy the book, but its too pricey....







entropy51 - 11-1-2012 at 17:23

Quote: Originally posted by AirCowPeaCock  
I think I'm going to stick to the hypochlorate-ketazine process NurdRage mentions
When I said in another thread that you might want to read some chemistry books, I was trying to avoid saying "instead of watching nurd rage".

AirCowPeaCock - 11-1-2012 at 20:59

Im going to guess you don't like the cook book sytke because it doesn't teach much about therory

cyanureeves - 12-1-2012 at 18:04

AirCowPeaCock how are you making your ammonia? i also used weak ammonia twice and my ketazine never separated so i did the other than nurd rage method twice also.i got two powders that differ in taste,one is salty and the other one is bitter ,both make mirrors with silver nitrate.i still want to do the katazine process but my ammonium nitrate sucked back water and exploded my glassware and no it was not borosilicate.what i thought was stout ammonia was about as stout as afterbite anti- itch which is 3%. i cant even imagine what the 29% stuff sold on e-bay smells like.

[Edited on 13-1-2012 by cyanureeves]

AirCowPeaCock - 12-1-2012 at 19:20

You tasted hydrazine-sulfate..twice?!?!?!

cyanureeves - 13-1-2012 at 05:32

AirCowPeaCock actually i have to admit i kept tasting the salty- lime one enough to shame myself. funny that i'm inquiring about ammonia because it also has a prohibited addiction quality affect on me.

vmelkon - 21-11-2012 at 05:25

**** Oops scratch that. I took the RFB off the condenser this morning and had a look from the bottom. There are long sharp crystals in there!

I did this reaction a couple of days ago. I used ammonia bought at Walmart. It says goldex on it
-250 mL ammonia
-75 mL MEK
-250 mL bleach 4%

The reaction worked! I obtained 10 - 15 mL of methyl ethyl ketazine.
Now for the problem. I added 62 mL of 6M H2SO4. It did form some a slight cloudiness which I presume was hydrazine sulfate.
I distilled it to drive off the MEK. It turned an orange color and is cloudy. What is this stuff?
I also collected the vapors since I wanted to recycle the MEK. It has 2 layers. Weird.

Could it be that my H2SO4 contain Pb++ because it comes from batteries and it caused problems?

[Edited on 21-11-2012 by vmelkon]

[Edited on 21-11-2012 by vmelkon]

Mailinmypocket - 21-11-2012 at 08:25

Quote: Originally posted by aaparatuss  
http://books.google.com/books?id=VqosZeMjNjEC&pg=PR8&...

chapter 11 of this google book
Small-Scale Synthesis of Laboratory Reagents with Reaction Modeling

has pretty nice work up for alcoholic hydrazine. I would almost buy the book, but its too pricey....




I have wondered why the ketazine approach seems to be the preferred one... I have always used the method in this book, I will attach the process here. If this poses a problem with the author I will remove it. There is no need for MEK and the process is very straighforward, all you need is some EDTA which is cheap and easy to buy on eBay and the like.

"In the present experiment, these are bound by the addition of a small amount of EDTA (~1 g/mol hypochlorite) [13]. The use of EDTA substantially reduces foaming and improves the purity of final product by keeping impurities in solution rather than in suspension."

The procedure is as follows:

11.3•…Experimental
11.3.1•…Hydrazine Sulfate

It is not necessary to use costly analytical-grade urea in this preparation. The technical- grade urea suffices, provided it is treated with ammonia to a pH of ~10.5 subsequent to dissolution in water, followed by standing for several hours and filtration of precipitates of iron hydroxide, etc.

To begin, 76 g (1.9 mol) of NaOH is dissolved in 68 mL H2O (this is about the minimum amount of water required at 25°C) and carefully added to 560 g (475 mL, 0.73 mol) of 11.5% NaOCl solution (these quantities can be adjusted if a hypochlorite solution of slightly different concentration is used), and the mixture cooled to approximately −10°C. Although the basified hypochlorite solution can be used at initial temperatures of up to 10°C, lower initial temperatures allow faster hypochlorite addition and, hence, shorter reaction times.

Next, 54 g (0.9 mol) of urea is dissolved in 46 mL of water (approximately the minimum amount). The dissolution is very endothermic and, hence, some heating is necessary to speed the process. The solution is poured into a 1-L, two-neck, flatbottom reaction flask equipped with a thermometer and a pressure-equalized dropping funnel, and surrounded by an ice–salt mixture. The dropping funnel outlet is loosely blocked by glass wool to hinder the inflow of oxygen (which slowly oxidizes the hydrazine) and is either vented in the fume hood or bubbled through an acidified KMnO4 solution that oxidizes the hydrazine.

A 3–4-cm stir bar is then inserted, 0.7 g EDTA is added, and the solution stirred while cooling to a temperature of about 8°C, at which point it becomes opaque and quite viscous. The basified hypochlorite solution is poured into the dropping funnel and run into the urea solution at such a rate that the temperature does not rise above 10°C. This should correspond to about 3–4 drops/sec., while the whole addition takes about 40 min. A much faster addition rate with a total addition time of 10 min raises the temperature to 25°C toward the end of the reaction with an increase in gas evolution due to Reaction 11.7, and yield loss of about 30%. However, even in this case, there is no substantive frothing.

When the reagents are fully mixed at a temperature of about 10°C, the solution is still noticeably yellow due to a substantial portion of unreacted hypochlorite. The temperature now needs to be raised to 72°C as quickly as possible to complete Reaction 11.4 and maximize the yield of the hydrazine intermediate, since a slow reaction favors the loss mechanism, Reaction 11.7. In practice, it is only necessary to heat externally to about 40°C, since a rapid exotherm (~4°C/min) commences at this point. As the temperature rises above 50°C, the deepening of color is due to the unreacted hypochlorite . When 72°C is reached, the reaction vessel is rapidly removed from the water bath and lowered into ice water. As the mixture cools below 50°C, it becomes essentially colorless, showing that all hypochlorite has reacted.

When the temperature of the reaction mixture has dropped below 10°C, 188 mL of 32% HCl (1.9 mol) chilled to −10°C is run in while stirring at such a rate that the temperature does not exceed 10°C. This minimizes the decomposition of hydrazine (the nitrogen evolved at this stage accounts for about 8% yield loss) as well as hydrazine loss in the CO2 flux. Initially, the addition is accompanied by the evolution of thick white fumes due to the formation of hydrazine hydrochloride; however, this soon clears. Next, a chilled mixture of 53 mL H2SO4 (1 mol) in 50 mL water is added at about 1 drop/sec., allowing the temperature to rise to just below 30°C.

The initial stages of the addition are visually accompanied only by the evolution of residual CO2 gas from the bicarbonate in solution because neutral hydrazine sulfate is very soluble. However, after about 0.3 mol of acid has been added, the bisulfate starts precipitating and the solution clouds. After all H2SO4 has been added, the solution is stirred for a further 15–30 min and then chilled in ice water. The added H2SO4 corresponds to a 0.55 molar excess, which lowers residual dissolved N2H6SO4 to about 1 g.

The precipitate is suction filtered, washed several times in situ with cold alcohol, and oven-dried at 100°C. The yield of the final product is 58–60 g N2H6SO4, which is 62% based on hypochlorite.

I've done this procedure twice now, on a scaled down run, and obtained ~20g each time. It can also be done easily in a few hours, which is nice.