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Rosco Bodine
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It is unlikely for there to be any acute poisoning .
If you used the quantities of acid specified
then there is no free hydrazine present past the end of the first half of the H2SO4
addition . And if you were using the HCl for the first part of the neutralization , the vapors from the HCl neutralize most of any hydrazine vapors ,
and keep the vapors in the flask as a sort of smoky fog similar to what you see when ammonia fumes and HCl vapors contact . The synthesis is a very
low emission , low fume method , so low that I don't even use a respirator or powered ventilation , but simply do the reaction in an open area
like a patio .
All I have ever done is use ordinary caution and not keep my nose stuck in the middle of the reaction , set the controls and step back from it , sit
in a chair maybe ten feet away and watch the reaction run , when it is attended at all .
You could have a chemical sensitivity / allergy sort of reaction , but it is extremely unlikely for you to have been
poisoned even if some of the mixture got onto your skin . The reaction mixture is
not volatile nor concentrated enough to
pose any serious danger , except to someone who may have a peculiar sensitivity like an allergy .
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garage chemist
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Is it possible to run the diazotation of hydrazine entirely in isopropanol? Then transesterification won't be a problem.
What is the solubility of NaOH in anhydrous isopropanol? I fear it might be too low...
But KOH dissolves much better in alcohols than NaOH, this might be an idea. This would yield potassium azide, of course.
KN3 gives metallic potassium on heating, so one might find it more useful than NaN3.
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Rosco Bodine
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| Quote: | Originally posted by garage chemist
Is it possible to run the diazotation of hydrazine entirely in isopropanol? Then transesterification won't be a problem. |
I believe it is very likely possible to skip the synthesis of the isopropyl nitrite , and to simply bubble N2O3 through the cold , basified
isopropanol extract of hydrazine ,
from which the NaN3 should precipitate directly in crystalline form .
| Quote: |
What is the solubility of NaOH in anhydrous isopropanol? I fear it might be too low...
But KOH dissolves much better in alcohols than NaOH, this might be an idea. This would yield potassium azide, of course.
KN3 gives metallic potassium on heating, so one might find it more useful than NaN3. |
NaOH has fair solubility in isopropanol , good enough for this reaction , but not nearly so good a solubility as in ethanol or methanol which is even
better still .
Of course those alcohols give rise to the transesterfication problem . KOH would
work , but how much would be gained in
terms of the lesser solubility of the KN3 in
alcohol would possibly be offset by the
added water content , since the KOH will
always contain more residual moisture .
My experience with isopropanol is that you
have to keep any extract absolutely as water free as possible , especially with any solid solubles present also which would be more soluble in the
moisture ,
because a phase separation is likely to
occur . The water content can separate
from the isopropanol carrying the water
soluble materials with it . To get an idea
of what I am describing , you can add ordinary NaCl to a bottle of 70% isopropanol and salt out nearly all of the water as a separated brine layer .
So
it is clear enough that the extract in isopropanol must be nearly anhydrous at
the beginning , and kept that way by being a fairly dilute extract , in order for the solution to remain a single phase which precipitates a dry
crystalline product of high water solubility such as NaN3 . It is a reaction condition where the product could easily separate as a
liquid brine , instead of an easily filterable solid , if the moisture content was only a little too much in the reaction . So the gain for losing
the transesterfication problem using isopropanol is that the nitrosation doesn't need to be run in a low pressurized system , which simplifies
the apparatus requirements . But the use of isopropanol creates a higher demand for a more anhydrous condition for the extract , and because of the
reduced solubility of the reactants in the
isopropanol the bulk yield possible from a given volume of reaction mixture is much
lower for isopropanol . If the methanol
extract can be managed with a pressurized apparatus , the yields from a liter of the methanol based reaction system are 3 or 4 times what can be
gotten from a liter of the isopropanol based reaction mixture , because of the
solubilities of the reactants . Worthwhile yields are gotten using either solvent or
even ethanol , but each has its advantages and disadvantages .
Microtek described his method using isopropanol and attached is a copy of
the text originally posted at E&W . I
would just link , but they are having
bandwidth problems so I hope this
attachment is acceptable .
An idea which I think would be worth experimenting , with regards to the direct
nitrosation of the basified alcohol extract
of hydrazine hydrate , is to use a methanol free denatured ethanol for the extraction , and do the nitrosation at
salted ice bath temperature . Using
ethanol would sort of be an intermediate
choice between methanol and isopropanol , which could have the advantages of each so long as the reaction mixture was kept very cold .
[Edited on 24-4-2005 by Rosco Bodine]
Attachment: Microtek NaN3 post from E&W.doc (27kB)
This file has been downloaded 2071 times
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garage chemist
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That's what I wanted to know, thanks!
So the solubility of NaOH in IPA is too low to be convenient, and using IPA brings the moisture sensitivity problem.
Mixing the IPA hydrazine extract with ethanol, dissolving the NaOH and adding the IPN (excess) under cooling will therefore be my method.
BTW, I just dissolved the NaOH in the NaOCl (as described in the preparation, in two steps) and quite a lot of white solid has precipitated! I assume
this is NaCl. Adding 50ml distilled water didn't dissolve it all, and I didn't want to add more water.
The NaOCl was 2 years old, that may be the reason. It likely contains more NaCl than fresh NaOCl, and this now precipitated.
I hope this won't cause problems other than a slightly lower yield.
I've put my stirring magnet into an 8cm teflon hose which had to be slit lengthwise to allow the magnet to be inserted.
This allows for better stirring.
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Rosco Bodine
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Studying the tradeoffs involving volatility scenarios from transesterfication , solubilities for the reactants , ect . ....
The best method in my mind for simplifying
the apparatus requirements , while still
having a good product yield from a given volume of reaction mixture , would be to
use a methanol free denatured ethanol
for freebasing the hydrazine . And then
to either use isopropyl nitrite obtained by
either microteks method , or the more usual method using nitrite and HCl , to
nitrosate the basified hydrazine extract
in ethanol , with the reaction done in a
salted ice bath . Alternately , simply bubbling N2O3 into the basified ethanolic
extract of hydrazine , cooled in a salted ice bath might work . Using ethanol should be the compromise which is easier for the extraction not being
as picky about the moisture , while providing better solubility and a more concentrated reaction mixture , and yet still having a not too low of a
boiling point for the transesterfication product which would be ethyl nitrite , which boils at 17 C . Salted ice would keep the reaction cold enough
if it was done slowly , to keep the nitrite in the reaction .
Methyl nitrite on the other hand , boils away at - 12 C , so it tries to escape even at very cold temperatures unless a bit of pressure is used to
contain it , the loss of nitrite is probably 50% , which is unacceptable .
So a variation on microteks method , but using ethanol for the extraction could prove useful , but only for denatured alcohols where methanol is not
the
denaturant . It is possible that some
other denaturants might be problematic ,
and this would have to be examined .
It is also possible that a methanol denatured ethanol could be stripped of its methanol in advance by bubbling through
it sufficient N2O3 to esterfy and volatilize
any methanol . Warming the alcohol would drive out any residual methyl nitrite
leaving essentially pure ethanol . This same methanol removal method could be useful for purifying methanol denatured alcohol for use in fulminate
synthesis , or other uses where the methanol denaturant is undesirable , and ethanol
alone is what is required . Hmmmm , the
revenue folks are sure to love this news  Transesterfication purified
moonshine anybody ? Pass me the jug 
Your two year old NaOCl is not NaOCl anymore . The storage life for the 10% is only a matter of weeks at cool temperatures . At subfreezing temps it
could be stored longer , but normal shelf life at ordinary temperature is very short .
[Edited on 24-4-2005 by Rosco Bodine]
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garage chemist
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Well if I add acetone to my 2 years old NaOCl, it still gets hot and starts boiling and splattering. 5% NaOCl only gets moderately warm, not warm
enough to boil off the chloroform.
Another question: after the reaction, do I need to add exactly 164ml of HCl or can I just add HCl until the gas evolution stops?
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Rosco Bodine
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Keep to the stated proportions regardless
of the physical observations . There is some overlap for the -Cl and -SO4 neutralizations so that the CO2 evolution is not a precise indication of
where the neutralization actually is in its progress .
I also believe the hydrazine is already largely tied up as a carbonate in the mixture , or as a complex with other carbonates . So you will get some
CO2 evolution beyond the point where you would expect it to stop , even into the addition of the H2SO4 . But the ratios
have been worked out to be optimum for
the precipitation of the HS at the end ,
in pure form . So use the quantities given .
Do a molar quantities analysis , neutralization equivalents and some extra
for operating margins , and you will see the arithmetic is already worked out correctly . Quantity variations were tried for experimental
confirmation that the math was applicable , which it was confirmed to be . I covered all the bases
on this HS synthesis . You can confirm that easily enough . It's like you are asking " are you sure " ....yeah I'm sure
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garage chemist
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OK, I just performed the synthesis.
I tested my NaOCl with acetone another time, and it became hot and a good amount of chloroform appeared in the flask. But it didn't start boiling
anymore (the last test was a few months ago). I estimate my NaOCl at around 7%.
I poured the urea/gelatin into the basified NaOCl at around 4°C. After 15sec. it became milky white and a bit of foam appeared.
But after 5min. only a small amount of foam had been produced, and the solution still was rather cool. I heated it, and this started the foam
production. The solution roughly doubled its volume (the foam got to the 1000ml mark) and became hot from the reaction (it could just be touched). The
generation of only such a small amount of foam was the first remarkable thing. After 10min I heated it further, and the foam subsided completely. The
solution was dark yellow/green. On further heating the color slowly became lighter. I heated it to about 80°C in 30min, then it was nearly colorless.
I cooled it to about 30°C, and added 217ml of 25% HCl. White fumes were produced in the reaction vessel, and lots of CO2 was produced. Then 50ml
conc. H2SO4 diluted with the same amount of water were added. There was still lots of effervescence until nearly the end of the addition.
Then a white precipitate rapidly appeared.
The solution was still quite hot! This was the second remarkable difference to my first try 2 years ago.
On cooling, a lot more precipitate formed. It is definately more than 15g! I'm expecting at least 25g.
The solution is in the cooling bath at the moment. Tomorrow I will further cool it down with ice to precipitate all the HS.
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Rosco Bodine
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Deep Orange is the color you should see when the foam is subsiding , almost the color of strong tea , but more orange than
red brown . That color gradually fades to
a very light ale color , almost clear at near the endpoint .
The quality and freshness of your NaOCl is really what is the single most important
factor affecting yields if you follow the rest of the procedure exactly . That is the one factor over which there is little control , except that you
can generally expect the fresh stock arriving at stores
from the spring through to the end of summer during the swimming pool maintenance season to be good quality .
If you plan on storing the 10% for any time , keep it in the refrigerator or freezer . Outdoors in warm summer temperatures it will be useless in
about
2 weeks . That temperature sensitivity
is exactly why the NaOCl must be freezing cold when you dissolve in it the NaOH ,
and do it gradually so as to produce no
undue warming of the solution , because the heating decomposes it on the spot ,
before it has a chance to participate in the synthesis of the hydrazine by doing its
decomposition in reaction with the urea .
The NaOCl is also pH sensitive , and it only can exist in alkaline condition . So
NaOH doesn't hurt it , actually even stabilizes it , but pH in the other direction
can immediately cause complete decomposition of the NaOCl , a situation
aggravated by warm temperatures .
Your old stock will gradually decompose to
a mixed solution of NaCl and NaClO3 ,
the ratio depending upon the pH and temperature . So use only the fresh stock for the HS synthesis if you can obtain it .
With some fresh NaOCl , and your 2 liter flask , if you did make an overflow funnel like I suggested using a 3 liter pop bottle ,
you could probably scale up to a .35 amount of the materials used in Mr. A's
improved method , if your stirrer is doing the job . Work with 665 ml of the NaOCl
and you should get about 80 grams of HS for your trouble . You can probably start that reaction a bit warmer if it isn't taking off on its own
exotherm and maintaining the reaction . Anywhere around 6 - 8 C should work fine . The fresh hypochlorite
is going to be more reactive , and the larger reaction mass should keep going from its own exotherm without any help in the initial stage of the
reaction .
[Edited on 24-4-2005 by Rosco Bodine]
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Mumbles
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I had a very odd happening when I made my first, and only batch of Hydrazine sulfate. I used the proceedure on Rhodium's then existant site. I
scaled everything down to 1/10 the values and modified the Hypochlorite level to account for my differing concentration.
There was absolutly no color change like described or foaming. It changed colors almost unnoticably. There was a yellowish-green color at the
beginning, no doubt from the bleach. It then changed slightly darker orange, and more of a yellowish near the end.
This experiment took place a while ago, but I have been vacant from this fine forum for a bit of time. Does anyone with some experience in the
proceedure know what was going on? Would the lower concentration or smaller ratio cause nearly no color to be imparted into the reaction, and there
to be a complete lack of foaming?
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Polverone
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If you used the procedure posted on Rhodium's, be aware that it was transcribed from this site. So basically read all that Mr. Anonymous / Rosco
have to say about the subject, then ask Rosco or the others who have followed his methods if you still have questions. Mr. Anonymous's messages
were posted under my username, so take that into account when searching.
PGP Key and corresponding e-mail address
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Rosco Bodine
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Are you talking about the urea and hypochlorite reaction , having no foam ?
That would seem impossible .
It would make sense for there to be less
instense color tint developed in a reaction
mixture which is diluted to about half the usual content of reactive components .
I haven't tried the reaction using ordinary
household bleach . But using the 10% pool chlorinator , the color reactions have been consistent , always the orange color
appearing , without exception , and always there has been plenty of foaming .
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Mumbles
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Yes, it was urea and hypochlorite. I have no idea what happened. I heated it exactly as the proceedure called for. It was very similar to your
proceedure actually. It came as a total suprise when there was not one bubble of foam produced.
I had expected for the colors to be somewhat less intense, but this was way too light from what I was thinking. The pictures I've seen of the
reaction and what I got were totally different. This was about the intensity of color as to what a good titration end should be, just barely visible.
I had to hold it up to the light to see any colors at all.
I got about 5-7% lower yields than what was described, which is expected from the lower concentration and smaller reaction size. This is the most
suprising fact to me. It didn't behave at all as was expected, yet I still got a normal yield. The product is primarily Hydrazine as well.
There was definatly a period of temperature that was cooled after filtering the HS, before the sodium sulfate precipitated.
I will make another attempt soon using my same reagents and proceedure and see if there is normal results, or if I recieve the same ones I had last
time. I haven't a clue as to what happened.
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Rosco Bodine
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That is very interesting . I would still recommend trying the proportions and the
use of HCl for the preliminary neutralization , as described in the improved method , as it should result in
better economy and improved crystals .
It could be that if you didn't increase the gelatine to account for the increased volume of the reaction mixture , that the viscosity of the
mixture was low enough so that the foam would not occur , and that the CO2 simply effervesced cleanly
without producing a foam .
I have actually wondered if there is not some sort of dispersion agent which could
be added to the more concentrated mixture to destabilize the foam and reduce the nuisance it presents . I tried reducing the amount of gelatine
which helps , but it also reduces the yields .
Perhaps another different chelation reagent could be substituted for gelatine
which would eliminate the foaming completely .
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garage chemist
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My problem is that NaOCl pool chlorinator is not available OTC where I live. They only have TCCA and H2O2 based stuff.
2 years ago I was able to buy 10 Liters of industrial chlorine bleach, which guaranteed to contain at least 14% NaOCl at the moment of delivery. (The
company doesn't sell to individuals anymore now).
Stupidly, I didn't adjust the ratios. I think that most of my produced hydrazine was oxidised by the excess of NaOCl. This would explain all the
foaming (nitrogen!) and the very low yield.
Now, the solution is old and weak.
My only source of NaOCl is the 5% NaOCl OTC bleach, which is actually rather cheap.
I will conduct experiments for hydrazine production from this.
I will use the same procedure as with the 10% NaOCl, I will only use double the amount of 5% NaOCl bleach. Everything else will be the same (amount of
gelatin, amount of urea etc...).
A 5% NaOCl solution is actually nearly indefinitely storage stable, the 10% pool chlorinator will eventually reach this concentration and then remain
at it, as I've read at several places.
BTW, silicone oil is a very effective foam suppressant. One drop is enough. Octanol also works.
But I'm not sure if this will help with the very rigid gelatin foam.
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Rosco Bodine
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There is an " extra strength " household
bleach usually labeled as " Ultra " bleach
and it is about 6 % while the regular bleach is usually 5.25 % NaOCl . The reaction for hydrazine should still work to some extent and you can
experiment to see what sort of adjustments may benefit the reaction with the lower concentration bleach . The disadvantage will be the lower amount
of hydrazine sulfate which is possible to get from a given volume of the reaction mixture . If the yields are similar percentages on a molar basis ,
then the economy of the reaction will be
unaffected , except for the increased labor and need for larger reaction vessels . Of course , if the foaming problem is gone then the volume
requirement for the reaction vessels will
not be reduced because of the larger volume required for the more dilute solutions for a similar batch size . And after the neutralizing acids are
taken into account , the volume efficency will be reduced . But if the process is still workable even with ordinary bleach , that is certainly a
valuable development for
being able to substitute a more readily available form of NaOCl .
It may be possible to make NaOCl of high concentration by reacting calcium hypochlorite pool shock with sodium carbonate washing soda , filtering out
the precipitated calcium carbonate from the calcium compounds , leaving a solution of NaOCl . It may be possible to boost the NaOCl content of
ordinary bleach by this method . One would need to do a weight loss on heating test for the washing soda to determine its state of hydration . The
Arm and Hammer brand which I tested is typically 83.4 % Na2CO3 and the remaining weight is water of crystallization
in the form it is found straight from the box . Other brands or lots may vary .
So this is a possible adjustment method which may be useful if it is needed .
However , if useful yields are still obtainable from ordinary strength household bleach , then it probably easier to just work with what is available
and
simply use larger batches since the process is very scalable up or down .
I have tossed around the idea that in an insulated container such as a large plastic lined picnic cooler , that a certain volume
and geometry reaction mass could probably achieve the conservation of its own heat of reaction sufficiently for the
exotherm to be sufficient alone to carry the reaction through to completion without any supplemental heating being required . If this is true , it
may be easier
to make HS in kilogram quantities in one batch , using several gallons of bleach at
one time in a large enough scale batch to
achieve that conservation of the exotherm . All that would be required then is to let the reaction run on its own exotherm to completion , and then
neutralize the mixture . On an industrial scale there seems no reason why this would not work , and down to a certain
limiting scale of perhaps three to five gallons of mixture , the same method may be adaptable to " small scale " method which is possible
in " picnicware " sized
insulated containers
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garage chemist
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I weighed my yield: 29 grams!
And this from 2 years old NaOCl.
From the theoretic yield for fresh NaOCl, I calculated my old NaOCl to be at around 5,3%.
Experiments with 5% OTC bleach will be conducted soonish.
Calcium hypochlorite isn't available where I live either (I live in germany).
I could theoretically make my own NaOCl by reacting chlorine (from TCCA) with NaOH, by this way, I could make up to 25% NaOCl which should give
impressive yields. But that would be a lot of hassle.
A question: as I understand it, the freebasing gives anhydrous hydrazine in isopropanol.
From the reaction
N2H6SO4 + 2 NaOH -----> N2H4 + Na2SO4 + 2 H2O
we see that two moles of water are produced per mole of hydrazine.
But the formed sodium sulfate is a drying agent and binds water according to this equation:
Na2SO4 + 5 H2O -----> Na2SO4* 5 H2O
So the isopropanolic hydrazine solution should be anhydrous, shouldn't it?
[Edited on 27-4-2005 by garage chemist]
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chloric1
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| Quote: | Experiments with 5% OTC bleach will be conducted soonish.
A question: as I understand it, the freebasing gives anhydrous hydrazine in isopropanol.
From the reaction
N2H6SO4 + 2 NaOH -----> N2H4 + Na2SO4 + 2 H2O
we see that two moles of water are produced per mole of hydrazine.
But the formed sodium sulfate is a drying agent and binds water according to this equation:
Na2SO4 + 5 H2O -----> Na2SO4* 5 H2O
So the isopropanolic hydrazine solution should be anhydrous, shouldn't it?
[Edited on 27-4-2005 by garage chemist] |
I would bet you would have the hydrazine hydrate in the isopropanol BUT they do use alkali to dehydrate hydrazine hydrate. Most reactions would not
require anhydrous hydrazine anyway so if you wanted the hydrate I guess adding a little water to the extract and removing an isopropanol azeotrope
under reduced pressure would be satisfactory.
P.S was not aware soonish was a word. I like it!
[Edited on 4/27/2005 by chloric1]
Fellow molecular manipulator
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Rosco Bodine
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usual behavior of hydrated salt does not apply
It would be nice if the alcohol extract of hydrazine hydrate was dried in situ by the
sodium sulfate , but the behavior of the
sodium sulfate with regards to hydrate formation is modified under these conditions . The temperature at which any hydration would occur is lowered
perhaps 30% , and the formation of the hydrated forms of sodium sulfate is undesirable since the water of crystallization invariably carries hydrazine
hydrate along with it , resulting in loss of hydrazine occluded in the crystals . The bottom line is the hydrazine is more hydrophilic and
hygroscopic than is the sodium sulfate which would be used to tie up the water , and the hydrazine wins the tug of war for the water . So it is best
to simply decant the alcholic extract of hydrazine hydrate , actually along with the additional mole of water ( it is probably hydrazine dihydrate ) ,
leaving the anhydrous sodium sulfate , operating at a temperature which precludes any hydrated salt formation . Better to get some water along with
the hydrazine , than to lose hydrazine along with the water tied up by hydrated salt formation .
Freebasing hydrazine into alcohol is something of an artful manipulation of solids and working with the solubilities of the components while trying to
eliminate completely as nearly as possible , having to actually add any free water to keep the mixture a paste which can be stirred .
Understand that there is a half-neutralization point for hydrazine sulfate , where a dihydrazine sulfate is formed , which has ten times the
solubility in H2O
at 60 C , as does monohydrazine sulfate from which it derives . At 60 C hydrazine sulfate is soluble to an extent of 8.3 grams per 100 grams of
solution , while the dihydrazine sulfate is soluble 84.7 grams per 100 grams of solution . So the mixture becomes thinner and more fluid to a point as
if it was melting , and then gradually thickens and almost sets up solid as the freebasing is completed by the introduction of the last half of the
NaOH .
A special strategy can be used to exploit the solubility change . You first introduce into the flask about half the hydrazine sulfate to be freebased
, and then in portions add about a quarter of the total amount of NaOH , until a thin stirrable slurry is formed , which will be hot from the heat of
reaction . Then in alternating portions to this stirrable mixture is added the remaining HS and NaOH , at a rate which maintains the mixture hot and
keeps the mixture fluid enough to stir .
When all the solids have been added and mixed together well , and before the mixture has cooled to the point of setting up solid , the alcohol for the
first extraction is added in a lump to the slurry , stirred well , and then decanted while still warm . This first extract contains most of the
hydrazine hydrate ,
probably ninety percent or more of the
hydrazine , and what remains is only what is physically trapped in the wet slug of crystals and cannot be decanted . Subsequent extractions and
decantations
of the alcohol simply reduce to a small remnant the amount of residue of hydrazine trapped in the wet crystals
which defy any filtration due to the air sensitivity of the hydrazine . The blanket
of alcohol fumes coming off the warm extracts affords some protection against air exposure during the brief times when the liquid extract is being
decanted from one container to the next . In between such transfers , containers must be kept stoppered . This is quite essential for preventing loss
of the air sensitive hydrazine . In the free form hydrazine is extremely reactive .
These are some pertinent references
GB900397 Freebasing hydrazine in ethanol
GB876038 Frebasing hydrazine in methanol
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garage chemist
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I just found out that the "5% bleach" is actually 2,8%. That is too low to be of use.
I will have to look around for a supplier for the 10% stuff. But I will first use up the 5,3% stuff, that will surely give me more than 100g of HS.
Thanks for the freebasing instructions, that was really helpful.
Ethanol could also be used for the extraction, I hope.
@ chloric1: I know my english is a bit funny, I sometimes use words which I read once, even if they are wrong or don't exist.
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Rosco Bodine
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My experience with the decomposition of NaOCl solutions is that once the decomposition starts , it is autocatalytic
and continues until the NaOCl content is zero , and only a solution of NaCl and NaClO3 is left as the product .
The decomposition doesn't " stabilize "
at some percentage like 5.25% and stop ,
but continues to complete decomposition .
It is pH related and temperature related .
Generally , the higher the initial concentration of NaOCl , the greater the instability and the shorter is the storage half-life , which is an
inherited instability for the lowered concentration solution at any point in time .
The 10% bleach is used for many other purposes than as a liquid pool chlorinator .
It is also used as a sterilizer wash for recreational vehicle waste storage tanks
and piping . So you may be able to find it
in the camping supplies section in some large stores . Some people also use it in their pressure washers for killing mildew on decks and for pressure
cleaning walls
and rain gutters on buildings , sidewalks ,
bathhouse / bathroom areas and I have seen it used as a washdown around dairies , delis and fish markets , butcher shops . Maybe a janitorial supply
would have it . It seems like it should be a common item .
[Edited on 27-4-2005 by Rosco Bodine]
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garage chemist
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I calculated:
If 108g NaOH are dissolved in 796ml water and chlorine is bubbled through (while cooling the solution with ice) until no more is absorbed, one gets
about a kilogram of a fresh 10% NaOCl solution.
Can somebody confirm my calculations?
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Rosco Bodine
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Stoichiometry gives me a headache
Sometimes a bit of background music helps .
Anyway , if you simply must resort to chlorination , it would probably be easier
to use regular bleach as the starting point , chill it feezing cold and go ahead and add NaOH in the quantity needed
for the added NaOCl , plus whatever extra
NaOH is to be added for the extra needed in the hydrazine synthesis . Rechill the solution , and chlorinate it with the vessel
sitting upon a scale until it has absorbed the necessary weight gain . The strongly
basified mixture will chlorinate more easily
and you will have one less step to do afterwards , plus the product will be more stable .
Attachment: 0wrapped.mid (60kB)
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garage chemist
chemical wizard
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Location: Germany
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I can as well start from plain NaOH solution than from the really weak NaOCl bleach.
What I don't understand is why you have to monitor the weight gain of the NaOH during chlorination! Why don't just bubble in chlorine until
no more is absorbed?
EDIT: sorry, I missed the part where you said that the extra NaOH is used in the hydrazine synthesis. Then chlorination would have to be stopped at
the right point.
But even weak NaOH vigorously absorbs chlorine, you can be sure that there will be no problems with unreacted chlorine even when you chlorinate until
all NaOH has been converted.
My scale only goes up to 500g, so I can't make a kilo of NaOCl with weight monitoring.
Perhaps add some extra NaOH after chlorination to bind the free chlorine, which would otherwise decrease the pH and destabilize the NaOCl.
I can get TCCA cheap and in large amounts, so I can make all the chlorine I'd ever need.
Calcium hypochlorit isn't available, though.
BTW nice background music! 
[Edited on 28-4-2005 by garage chemist]
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Rosco Bodine
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The factors which would have me suggest you use bleach as a starting point and strengthen that bleach are several .
The gallon of bleach is already at least halfway there to being what you want in terms of its NaOCl content , plus it also contains the distilled
water you will also
require , along with the NaOH and Cl which would have to be purchased separately , and all three components then used to form what is the product
which is sold cheaply . Also , half of the
thermodynamic of a highly exothermic
process has already been managed ,
which is really the greatest technical difficulty . So it is for reasons of economics involving the cost of materials
and for technical thermal considerations ,
that it is better to strengthen regular bleach than to start from scratch . You can probably buy the already made bleach more cheaply than you could
buy just the distilled water and sodium hydroxide required for making the same product .
Chlorinating to a specified weight gain of absorbed chlorine , with sufficient alkali in excess to maintain an endpoint at pH 11 or higher is the
standard method for producing a stable product . If you chlorinate to a point of saturation , you will drop the pH and it will destabilize the
solution producing chlorate instead of NaOCl . Also the water must be especially pure for stable NaOCl solutions ,
as even a few hundreths of one part per million of ions such as nickel , cobalt , copper and iron , cause catalytic decomposition .
The reaction for the formation of the Javelle water ( bleach ) , from chlorination of NaOH solution follows from the first reaction of Chlorine and
water .
Cl2 + HOH -----> HCl + HClO
and in the presence of NaOH ,
( Cl2 + HOH ) + 2 NaOH ----> NaCl + NaOCl + 2 HOH
So , on a molar basis , ordinary bleach has
as much salt in solution as it has sodium hypochlorite .
By what method are you going to generate the Cl from the TCCA ?
[Edited on 28-4-2005 by Rosco Bodine]
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