Azides

There is some of Microtek's method in there for sure, and also some of yours. For this experiment I did the freebasing with just a few drops of water and no alcohol until the end, all in an erlenmeyer with a ground glass stopper. It is sort of a combination of Microtek' s method and yours, with a twist.

A book I have been reading states that it is inferior to do the freebasing in alcohol. According to Leonid Lerner
in "Small scale Synthesis of Laboratory Reagents", there is a large amount of insoluble gel produced when freebasing in alcohol because the sulfates are insoluble in alcohol. This insoluble sulfate gel locks in Hyrazine Sulfate, and prevents it from reacting with the hydroxide, which lowers yield. I think in small quantities and with a bit of trituration, the alcohol method is probably ok. In larger scale synthesis no alcohol is definitely best.

In regards to the yield, I wasn't using my best scales so I could be off a percent or two I guess. My scales weighing heavy by 0.05g would lower the yield by about 1.2%, if heavy by 0.1g then the yield would be lower by about 2.5%. I have compared these scales on several occasions to better ones and they were not off more than that.

I just took the mass of the sample again after a day of drying to see if it had lost any more moisture, it hadn't.

Is KOH really the limiting quantity with a 76% yield, if using a stoichiometric quantity? According to the same book as above, I could have gotten a yield of 86% KN3 or 90% NaN3 by this method.

I just went through the stochiometry, and there was about 5% excess of KOH used. I think there may have been some NaOH carry over from the freebasing too (slight excess used there as well). I was using my notes that I used before for the NaOH method, and just increased the amount to adjust for the heavier potassium cation, so I must have used an excess with the NaOH method as well. Now that I am actually looking at the bottle of KOH, it says Potassium Hydroxide Reagent, Assay (KOH) 87.4%, Potassium Carbonate (K2CO3) 0.81%, and a list of other trace contaminants all totaling 88.24%. The balance must be water. The container is well sealed.

I guess I could be off by a certain amount, but I don't think it is more than a couple percent. Thanks for pointing that out, I hadn't thought it all through actually.

I am very happy with this method. It isn't quite as quick or as easy on alcohol as your method, but it is simple and straight forward using only a flask as equipment (a stirrer helps a lot to dissolve the hydroxide in the alcohol though). Potassium Hydroxide might be a little harder to obtain than NaOH for some people.



BTW, we may need to add a couple more percent to the yield. I kept the reaction liquid after collecting the crop of potassium azide. I just looked now and there is another small amount which has precipitated in the last day or so. If I am going to keep saving it, I have got to stop keeping it in plastic bottles.


[Edited on 8-8-2011 by Hennig Brand]

reference #15 for Carbamoyl Azide article

freebasing hydrazine related

Glauberite byproduct possibly useful in freebasing

Quote: Originally posted by Rosco Bodine

The experimental part of the attached describes the reaction of nitrous acid and semicarbazide producing a 70% yield of Carbamyl Azide. A translation of the relevant portion would be helpful if anyone may assist, thank you. Über die Ultraviolett-Absorption und Konstitution von Tetrazenen aus Aminoguanidinsalzen Ruth Hofsommer, Max Pestemer Zeitschrift für Elektrochemie und angewandte physikalische Chemie Volume 53, Issue 6, pages 383–387, Dezember 1949 DOI: 10.1002/bbpc.19490530612

Quote: Originally posted by Rosco Bodine

Also back on page 3 and 4 of his thread S.C. Wack posted some attachments which are are scans of articles relating to oxidation of hydrazine sulfate with H2O2 and nitrous acid and other oxidizers. Some more legible scans are now available and these are also attached as an update. A New Synthesis of Hydronitric Acid (attached) The Oxidation of Hydrazine (attached)

Should probably put this here too....Solubilities for Hydrazine Sulfate and Dihydrazine Sulfate
Can't find a chart for the solubility curve, so I borrowed this excerpt via printscreen screenshot, you know sort of ripped it ......sharing is caring

Quote: Originally posted by Polverone

Quote: Originally posted by froot I found an interesting route to NaN3 and HN3 from a old book called 'Van Nostrand's scientific encyclopoedia' Word for word as follows; Hydrazoic acid is formed (1) by reaction of ethyl or amyl nitrite in NaOH solution (sodium azide formed), then acidifying with dilute H2SO4 and distilling. Hydrazoic acid is recovered mainly in the early portion of the condensate I am sure that the first reaction is wrong. There needs to be hydrazine in there. Alkyl nitrite + NaOH just results in an alcohol and sodium nitrite.

Quote: Originally posted by Bhaskar

Are u completely sure on the ethyl nitrite and sodium hydroxide forming hydrazoic acid reaction? Because i realy wanted to synthesis my first azide

review of untested possible aqueous reaction system methods

Quote: Originally posted by Rosco Bodine

Yeah the Dihydrazine Sulfate reportedly is stable. The reason the acidic salt, the monohydrazine sulfate is the common form is because it is the low solubility product precipitated from acidic solution which facilitates its isolation in relatively pure form from synthesis. So the monohydrazine sulfate is the common form of commerce, and the common form for the reagent. But definitely there are other forms of further processed hydrazine which are also stable and may be required for certain syntheses. It is a similar story for ammonia and other bases where various salts and/or even the anhydrous base are stable but have their various differing properties and reactivity and storage requirements, toxicity, volatility, ect. ranging from benign conditions to extreme. To make an analogy, hydrazine sulfate corresponds with ammonium bisulfate or sodium bisulfate and Dihydrazine Sulfate is the neutral salt corresponding with ammonium sulfate or sodium sulfate which more correctly and precisely in reality are Diammonium Sulfate and Disodium Sulfate. As for the danger aspect of working with smaller volumes of material which should be easier to manipulate with the endproduct being the same hazard ....usually a simpler process manipulation of a smaller amount of raw material increases safety and is not any more risky ....so it seems it would about the same or lower risk. I can't really report an observation on this because I haven't actually done this yet to confirm. What works on paper doesn't necessarily always materialize that way in the experiment. But this one seems pretty straightforward like it ought to work okay. There is another calcium salt of possible interest with regards to hydrazine conversion to azide and this is another possibility for experimentation which was mentioned in another thread. http://www.sciencemadness.org/talk/viewthread.php?tid=874&am... It has seemed possible to me that an organic nitrite may facilitate the reaction somehow and is more selective in converting hydrazine to hydrazoic acid than is free nitrous acid. It has therefore seemed possible that something like sorbitol or glycerin or isopropyl alcohol in an aqueous solution of a neutral hydrazine salt such as Dihydrazine Sulfate, might react as a regenerable intermediate organic nitrite with Basic Calcium Nitrite Ca(NO2)2 - Ca(OH)2 to yield an aqueous solution of Calcium Azide over precipitated Calcium Sulfate. The Calcium Azide solution might then be converted to a solution of Sodium Azide with precipitation of Calcium Carbonate, by treatment of the solution with Sodium Carbonate. This is another completely hypothetical and untested idea for an experiment. It may not work at all in a beaker even though it seems to work fine on paper. Attached is US4294813 which describes a synthesis of Basic Calcium Nitrite from Sodium Nitrite and Calcium Nitrate

Identifying possible routes to azides which are workable in an aqueous system has been something that I have had in mind for 10 years because it would simplify the syntheses for not requiring use of alcohol as a solvent and would eliminate that expense as well as eliminate the tedious extra efforts attendant to manipulation methods and strategies seeking low water content in the reaction system.

There was brief discussion between myself and Engager in another thread linked in the quote above referencing the silver azide gotten by Hogkinson as an indirect method reported for producing azide in an aqueous system. That method is one which I have tried and been unable to reproduce, which lets me know it is a fickle reaction having a narrow window for conditions which will work, that I was unable to reproduce. The literature in general does not offer much helpful and detailed information about synthesis methods for azides from an aqueous reaction system, but makes only brief references to the azides being produced as products of decomposition of the subject material of such literature where the precursor for the azide is given the authors attention, and the isolation of azide as the intended reaction product is not contemplated. So the available literature is very brief and not very helpful in regards to describing any syntheses done in an aqueous reaction system where azide is the intended product. That absence of information is the cause of interest in formulating experiments which seek to provide good information which fills that obvious deficiency in the literature. Even textbooks, at least the older texts make oversimplified references to how azide is obtainable, generally referencing Curtius use of KNO2 and Hydrazine Sulfate, and providing no details. So bravo to Curtius step right up and tell us all about it how it is done. Until then we shall examine what may be "other" bona fide methods than proposed by either Curtius or Hogkinson, frankly both of which reports I greet with skepticism born of experience having difficulty confirming their reports. I have successfully made azide many times and different ways, but all of these variations still have involved free hydrazine in alcohol reacted with an organic nitrite in the presence of a base. It is perplexing to identify the alternate conditions where an aqueous reaction system may be used with good results.

Three possible methods using an aqueous reaction system have been identified. The method proposing use of Calcium Nitrite and Hydrazine Sulfate perhaps in the presence of a polyol described above and in the linked discussion with Engager is one method I have contemplated but have not tested. The other two methods are the hydrolysis of a carbamoyl azide intermediate briefly described by literature as obtainable from nitrosation of semicarbazide or hydrazodicarbonamide ( Biurea )

From what little time I have been able to spend on this interest at times over the course of the past 10 years of following these threads and looking at the literature this is my summary review of my own conclusions and my impression of where experiments have led and the 3 most promising methods yet to be examined.

The methods involving alcohol reaction systems are solidly proven to work as methods for synthesis. But the possible methods involving an aqueous reaction system remain inadequately reported and/or mostly unexplored, untested, and speculative .....for now.

[Edited on 30-3-2013 by Rosco Bodine]

Yes azides are definitely a subject of interest for which a good practical working knowledge is a priority for anyone interested in the scientific art associated with initiating explosives. It could be prioritized as "Explosives 101" kind of fundamental must have knowledge buried and hidden among that voluminous work they would not dare to teach in college , a deficiency and oversight which any aspiring "blaster" would then seek to remedy as knowledge gotten from "independent further research". Of course that would be the point to not "spoon feed" every secret thing to the student, but only sufficient knowledge to operate as a provocation to the student who must then solve any remaining mystery for themself. We are taught only to a point, and thereafter we are self-taught and this is probably by design. The impatient to know would criticize the design and question its necessity, question the teachers, question the intelligence of the design. It is what it is.

If we stick with the well proven non-aqueous methods there would still seem to be improvements possible to be made in the manipulations. My personal impression is that a scheme which uses the dihydrazine sulfate prepared in advance as the material which will be freebased into alcohol, very likely would represent such an improvement. Isopropyl alcohol is a good choice for the alcohol as described for the method of microtek and its variations. There possibly could be advantage for use of different organic nitrites other than isopropyl nitrite, or maybe not. Surveying the possibilities there are other organic nitrites which may have lower vapor pressure and possibly adequate stability, and which will either react directly with the hydrazine in isopropanol or will transesterfy in situ to the isopropyl nitrite which will allow the desired reacton to proceed. Depending upon availability other alternative solvent alcohols are also workable. So it appears that the "alcohol solvent method" is general and may be subject to variations at the technicians discretion which may serve as refinement applied to the same basic method.

Ultimately there will be found several slightly different but still related methods all of which are workable with each approach having its advantages or disadvantages compared with another variation. What will ultimately prove to be the "best" all around combination of solvent alcohol, organic nitrite ester, and base, and hydrazine salt precursor material, is left to be sorted out with further experiments, while encouraged to know that decent yields are probable to be gotten from any of the variations, as whatever variations are tested to try to optimize the particular combination.

There is plenty there to digest when surveying the "process chemistry" involved, plenty of food for thought there for the hungry mind of the curious experimenter.

[Edited on 1-4-2013 by Rosco Bodine]

Quote: Originally posted by Rosco Bodine

If we stick with the well proven non-aqueous methods there would still seem to be improvements possible to be made in the manipulations. My personal impression is that a scheme which uses the dihydrazine sulfate prepared in advance as the material which will be freebased into alcohol, very likely would represent such an improvement.

I was having a little fun earlier with some folks here, probably with Len in mind more than others, sorry I couldn't resist

Look again at the titling on that post paragraph linked above usual behavior of hydrated salt does not apply and you will understand why it would be of limited usefulness to try to use any ordinary dessicants to try to dry an alcohol solution of hydrazine hydrate. The hydrazine hydrate tenaciously holds onto water and wins the tug of war for the water unless some special approach is used like distillation fractionation or azeotroping a solvent / water mixture, or in the alternative to use chemically reactive schemes like an alcoholate such as sodium ethoxide or sodium methoxide as a part of the neutralization scheme in place of simply using a base like NaOH simply dissolved in the alcohol.

The speculation which I was making about Glauberite was more intended towards a cleaner precipitation of the sulfate byproduct of the freebasing having a more compact crystalline form, than was it meant to address at all the byproduct water, which Glauberite would not do anyway since Galuberite is an anhydrous double salt. The Glauberite would likely have its greatest utility in the prelimary conversion of the monohydrazine sulfate to dihydrazine sulfate where the dihydrazine has such great solubility in water, and before an alcohol system is later used for the freebasing scheme applied to a previously isolated and dried dihydrazine sulfate. It is possible the Glauberite may have utility also in the freebasing scheme, but it would not be any dehydrating property that is the reason. The lowered solids content would make for easier physical manipulation to stir a slurry of sulfate byproduct, and by working with dihydrazine sulfate there will only be half the bulk of byproduct sulfate, as well as half the byproduct water in the freebasing and extraction stage.

The added quantity of alcohol for the more shortcut scheme is simply the relative amount of alcohol being greater to have an end resulting solution having a comparable concentration of water. Twice as much alcohol is required for the shortcut scheme (at least) and maybe even a little more in comparison to the proposed scheme which involves an easier manipulation for physical reasons.

If an alcoholate is contemplated being used also as a chemically reactive dehydration, there is benefit there also because only half as much byproduct water is encountered when freebasing the dihydrazine sulfate as is gotten by the "one pot" shortcut method. For a bulk synthesis expecially where a larger amount of material will be made, these refinements would be of greater concern with regards to the efficiency of the process. For small scale syntheses, the simplicity of the "short cut" method makes waste of solvent or inefficiency less concern, but for any scaling up of the process, the usefulness of the refinements would become apparent. Since I tend to work medium scale then I am more aware of these kinds of "process" efficiencies, which could also be applied to the smaller scale if it was estimated to be worth the extra effort on the smaller scale.

To expound upon what I am trying to communicate it would be good to see the following post in the dedicated hydrazine thread. It further describes what is contemplated as a method for virtually anhydrous hydrazine in isopropanol possible to be gotten by freebasing dihydrazine sulfate using aluminum isopropoxide in isopropanol. I do not know if this has ever been done. But it appears to be the logical progression that such a proposed route is possible.
http://www.sciencemadness.org/talk/viewthread.php?tid=1128&a...

As an aside there is also some modification of the hydrazine synthesis reportedly using manganous sulfate as a catalyst. The "Russian method"
from a Russian textbook Practical_Inorganic_Chemistry.Vorobyova.O.I_Dunaeva.K.M_Ippolitova.E.A_Tamm.N.S.1987
http://www.sciencemadness.org/talk/viewthread.php?tid=1128&a...

There is a patent reported US3227753 Biurea or Hydrazine from Hypochlorite and Urea which describes a similar process so this may be of interest as a possible further refinement on the hypochlorite urea process.

http://www.sciencemadness.org/talk/viewthread.php?tid=1128&a...

Scale absolutely has bearing on the choice of methods used for convenience. Shortcuts are allowed for small scale work, and I never really explained before that was what was deliberately done to make a "one pot" method from a generally more complicated industrial process. It is good to know this however, because it can apply if any scaleup is contemplated or if problems are encountered with the small scale "one pot" methods, then those problems may be resolved by the longer route or other measures done to refine the process.

Brainstorming is allowed also. For example I just thought of the possible refinement of using aluminum isopropoxide in ethanol, denatured alcohol to do the freebasing of dihydrazine sulfate, resulting in anhydrous hydrazine in ethanol with a small percentage of byproduct isopropanol, a solvent system being mostly ethanol in which the NaOH would be highly soluble. Then for the nitrosation a low volatility nitrite like diethylene glycol dinitrite, or alternately butyl nitrite or amyl nitrite, or if stability of glyceryl di or trinitrite is sufficient, then the glyceryl nitrite could be used.
Such a scheme could lead to a quantitative yield for the process regardless of scale.

So now you know where "Mr. Anonymous" was going with all of this that took ten years to get said ....connecting all the dots. Dots are hereby declared "connected".

I really wanted to get all these details down before the next forum backup so the communication transmission would be complete. I'm sure there was an article or two missed along the way, but that is pretty much all I've got on this to this point, for the "hydrazine chronicles" or Martian (lander) chronicles, or azide / tetrazole chronicles ....whatever. It has been a long ride, but a lot of fun sharing.

[Edited on 1-4-2013 by Rosco Bodine]

I have been wondering for a long time why this thread was not stickied.

Since brainstorming is allowed, I have another idea.

Notes on the Preparation of Absolute Isopropanol

Lewis Gilson

J. Am. Chem. Soc., 1932, 54 (4), pp 1445–1445

Publication Date: April 1932

Attached jpeg of the note on concentrating isopropanol.



I don't know but it looks like maybe the isopropanol could be used over and over again. Just remove water and use it again. Again probably not worth the bother, but it might be worth saving the solvent and doing it in large batches.

I suppose since the isopropanol is used in such large proportion compared to what is used in the case of ethanol or methanol, the solvent could probably just be recharged with reactants and used again.

[Edited on 2-4-2013 by Hennig Brand]

A few more dots yet to connect about sodium azide

Hodgkinson patent related

In my first communication 10 years ago I mentioned the Hodgkinson patents, which have been posted about maybe 3 or 4 times since obtaining copies of those patents. GB128014 is still intriguing. Hodgkinson indicates it is a fickle reaction occurring in a very specific narrow range of pH but is somewhat cryptic about giving that pH a number.

http://www.sciencemadness.org/talk/viewthread.php?tid=874&am...

The reaction between an alkali nitrite and the neutral hydrazine salt is described to occur in an only slightly acidic solution not so acidic as to redden litmus which would be a lower limit of 5 pH or perhaps 4.5 pH. Hodgkinson mentions the reaction as comparable to the pH of a solution of boric acid but does not specify the strength of the example solution of boric acid, which even at about half of saturation at room temperature would be on the threshold of being too low pH and would definitely redden litmus. So Hodgkinson is being mysterious while claiming yields of 85% for his mysterious aqueous system process. There are recent patents claiming reaction of free hydrazine and an organic nitrite in an aqueous system in the presence of a base.
And there are some early art references mentioning use of a inorganic nitrite in reaction with a hydrazine salt but the references describe acidic conditions, some of them highly acidic conditions. There appear to be 2 different mechanisms and possibly 3 different mechanisms and the mechanism involving a highly acidic reaction mixture is an oxidation, having about one third of the potential yields of the alternate scheme of nitrosation or diazotization done in an alkaline reaction system. Hodgkinson seems to teach that the nitrosation mechanism will still occur if the reaction system is only very slightly acidic, and does proceed in an aqueous reaction system. The pH range would seem to be in the range of bromocresol green or bromocresol purple or alizarin. Hodgkinson offers no help on process monitoring indicators except for mention of litmus. Hopefully that can be updated to an indicator having a sharp transition for process monitoring any experiments. What coloration may occur in the reaction mixture could be a factor but is unknown.

Hodgkinson is cryptic also about the needed amount of alkali which he supposes must be present to maintain the precise acidity and specific pH for the reaction system. Stoichiometry reveals that a full molar equivalent of NaOH or probably better NaHCO3 would be required along with the NaNO2 in order for the reaction to remain close to neutral. But the description given by Hodgkinson states that the small impurity of alkali expected to be present in the sodium nitrite would provide adequate buffering ....when the reaction stoichiometry does not suggest this would hold true. Hodgkinson hedges his description by conceding that some added amount of alkali may be required if sufficient alkali is not present in the nitrite , when the stoichiometry suggests that such need for additional alkali is a certainty. My own reckoning of what would be needed is an equivalent of NaOH or NaHCO3, and probably what would be more workable still would be some replacement of that equivalent with a not yet predicted but probably small amount of NaOAc which would serve as a buffer to maintain the highly specific pH requirement described by Hodgkinson.

This azide synthesis described by Hodgkinson continues to be intriguing to me, particularly because of the reported high yields from what appears to be a mild reaction condition, but a fickle reaction requiring great precision to accomplish ...IF indeed it works as described or can be made to work by some slight modification of what is described, after ascertaining what little secrets Hodgkinson may not have mentioned while describing the process. I do not think it was just "inventors euphoria" or wishful thinking that would have Hodgkinson apply for 2 patents and associate the invention with the Ordnance College of England, so there is probably some validity to the patent, even though it is clearly NOT a patent which makes "full disclosure" of all the factual particulars in great detail. This leaves the matter art which must be puzzling to more persons than just myself, with regards to ascertaining the full details of precisely how such a reaction must be conducted in order to work as described only generally. I have tried in the past to make this process work and it failed, but I was not observant of the highly specific pH which evidently is THE absolutely imperative requirement.

Studying the reaction and doing experiments possibly could lead to formulating exacting proportions of the required ingredients so that the target pH would be achieved by
buffering and then the process would be reliable and reproducible.

Attached are some related reference materials which may help trying to model the reaction, particularly with regards to the proposed buffering aspect for the nitrite in admixture with NaOH or more likely NaHCO3, and NaOAC which might be required to make the process workable. In place of NaOAC, NH4OAc, borax, or ammonium borate might also be workable as part of the reasonably believed to be required buffering scheme which Hodgkinson neglected to describe in full detail.

One thing of collateral interest which Hodgkinson did describe is the conversion of the slightly soluble hydrazine acid salt to the highly soluble neutral salt. That much is something I and others have confirmed does occur.


Attachment: GB128014 Hodgkinson azide patent 1.pdf (185kB)
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Attachment: NO2 generation by NaNO2 plus Boric Acid solutions.pdf (81kB)
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Attachment: pds-borates-optibor.pdf (88kB)
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Attachment: pds-borates-ammoniumpentaborate.pdf (54kB)
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This would seem to be a likely candidate indicator



Further investigation of the Hodgkinson azide synthesis by experimental modeling and if possible by historical research into the process as conducted looking at any industrial records or additonal writings of Hodgkinson or others employing the process, would make an excellent PhD dissertation and thesis for some graduate student .... you know ...just sayin' this would be a cracker jack good one for some poor soul trying to think up something, anything worthy as a subject for that important research paper.

Nothing like stirring the pot Maybe this Hodgkinson azide synthesis will intrigue somebody else as "lost art" which has far too long been missing from the literature and textbooks, seeing that odd omission should be remedied with full disclosure which will remove it from obscurity as lost art, found once again. Now there's a doctoral thesis idea for ya.

Biographical for Hodgkinson
William Richard Eaton Hodgkinson, Ph.D.
(1851–1935)
Professor of Chemistry and Physics, Ordnance College, Woolwich. Cotton Professor of Chemistry and Physics, R.M.A., Woolwich.

FYI & FWIW
http://parazite.nn.fi/roguesci/index.php/t-3211.html
(attached)

Attachment: Azides from Hydrazine Salts GB128014 and GB129152 [Archive] - The Explosives.pdf (28kB)
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Also there was some discussion between myself and PHILOU Zrealone, ( Louis , Ph Z ) at the old alt.engr.explosives news group years ago regarding uncertainties about the Hodgkinson patent which remains mysterious
http://alt.engr.explosives.narkive.com/hUjeaYs1/azides-from-...
(attached)

Attachment: Azides from Hydrazine Salts GB128014.pdf (265kB)
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[Edited on 13-4-2013 by Rosco Bodine]

Right. I couldn't make the Hodgkinson process work and I definitely tried using careful technique and different approaches and using pH test strips frequently.

I think a variation on what Hodgkinson has described may possibly work but I have not figured it out yet. It is like a rubicks cube, I pick it up and mentally play with it from time to time as a WTF is going on there kind of mental exercise I don't like it when a patent stumps me. But some of them do, and this wouldn't be the first to come out of a "war college" laboratory, there was another one called Emmansite IIRC which was actually just picric acid with an HNO3 of crystallization. Similar kinds of cryptic stuff is sprinkled a few places with typographical errors in PATR that have caused perplexing misinterpretations, where the reader must become the proofreader and editor to get the actual facts.

Lately I have been reviewing some of the original and antique literature on azides and will be posting some of it here.

The method which I described for freebasing hydrazine hydrate into methanol, and the variation of Microtek for isopropanol are perfectly valid syntheses for a lab scale sort of "one pot" method. The nearer anhydrous is the reaction system done in alcohol the better will be the yield and simplifies things greatly since it can simply be filtered out of the spent reaction mixture. Towards that end of keeping the final water content minimum I think the best approach is to use the base or the greatest portion of the base in the form of the alcoholate made separately. I believe there may be a lower practical limit for the water content due to at least a tiny portion of water being needed in the freebasing of the hydrazine sulfate.

One of the early researchers Thiele actually performed the reaction of hydrazine and ethyl nitrite using sodium methylate as the base and dehydrating agent, both in excess with respect to hydrazine, and the reaction solvent being ether, Thiele obtained approximately quantitative yield based upon the hydrazine. So this pretty well proves that for a one pot and single pass method, the "dry solvent" approach works for ether or alcohol.



The disadvantage of the aqueous system methods is needing to recycle unreacted materials, and having a heavy mixture of byproducts requiring some scheme for separation, which presents isolation difficulties. Even for the aqueous system methods, in contrast with Hodgkinson other investigators report that the organic nitrite ester and a basic reaction system provides a more rapid reaction and better yield than the alternative which Hodgkinson describes incompletely, and that finding by others makes Hodgkinson even more doubtful.

I think the benefit of Hodgkinson is that some of the things suggested there may have validity ...and usefulness but in other context...so you can make use of those parts, while thinking about the rest as dubious. Hodgkinson was getting on up in years ( 67 ) when the azide patents were published, so there may be some sense of humor injected by the old man into those patents, the kind of humor that might arise with some senility Old Ph.D's don't go nutters with age, they only become "eccentric"

Much of the German is understandable from recognizing the chemistry, but any help with actual translation to English of these articles is welcome and appreciated.

Zur Darstellung der Stickstoffwasserstoffsaure
Johannes Thiele
Berichte der deutschen chemischen Gesellschaft
Volume 41, Issue 2, pages 2681–2683, Mai–August 1908
(attached)
Attachment: Thiele Berichte.pdf (175kB)
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Uber die Einwirkung von Salpetrigsaureestern auf Hydrazin, Phenylhydrazin und Benzhydrazid in alkalischer Losung
R. Stolle
Berichte der deutschen chemischen Gesellschaft
Volume 41, Issue 2, pages 2811–2813, Mai–August 1908
(attached)
Attachment: Stolle Berichte.pdf (161kB)
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Also here is an older article by Curtius which is more general about azides
Attachment: Curtius Journal_of_the_Switchmen_s_Union.pdf (691kB)
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[Edited on 17-4-2013 by Rosco Bodine]

DE205683 Translation to English

Possible novel variation on Hodgkinson

The conditions which are described by Hodgkinson seem possibly adaptable and applicable to use of different reagents in a similar reaction scheme, which I am uncertain will work. The variation which I have contemplated involves addition of isopropyl nitrite to an aqueous solution of acetone azine, with the expectation that the organic nitrite will react with free hydrazine present from hydrolysis of the acetone azine to produce hydrazoic acid, with a specific pH being maintained by concurrent addition of a base, perhaps sodium bicarbonate or ammonium bicarbonate or their respective acetates in some combined buffer scheme. I believe that within a very specific and narrow range of pH that a similar reaction scheme as described by Hodgkinson may occur and if workable would have advantages particularly in excluding unwanted byproducts.

Theory / Hypothesis / Experimental : When the dimethylketazine is dissolved in water, there is sufficient hydrolysis to cause the solution to become basic due to the presence of free hydrazine as the hydrate with 2 molecules of byproduct ketone, in this case acetone, which results in a quaternary system in hydrolytic equilibrium, consisting of hydrazine hydrate, water, and acetone, along with unhydrolyzed dimethylketazine. When isopropyl nitrite is added to the alkaline system it should react with the hydrazine hydrate to form hydrazoic acid, and this will have the effect of lowering the pH which favors further hydrolysis of the reserve lode of dimethylketazine, producing more hydrazine hydrate for further reaction with incoming isopropyl nitrite. In the slightly alkaline pH range is where the reaction would be anticipated to proceed as described, where the hydrazine would be present as the freebase hydrate, reactive with the isopropyl nitrite. The natural tendency of the reaction would be to become increasingly acid from the hydrazoic acid, which would tend to interfere with the desired reaction, unless there is additional base added concurently along with the isopropyl nitrite to neutralize the hydrazoic acid and maintain the slightly alkaline pH. If the pH were allowed to go too far acidic it would tend to quench the desired reaction, because free hydrazine would itself act as a base to neutralize the hydrazoic acid forming hydrazine azide, and another issue would arise with reactivity of the isopropyl nitrite with the acetone as in the acidic condition the hydrazine would compete to be nitrosated, while nitrosation of the acetone would be favored in the acidic reaction mixture. Even though the reaction may be quenched by insufficient neutralizing, it should recover and proceed when the pH is raised again into the operative range of alkalinity. The only foreseeable issue for improper buffering is that some undesired byproduct may occur for the nitrosation of acetone which had not been avoided by allowing pH to transiently range too low, but there would be no hydrazine loss and only a wastage of isopropyl nitrite as the consequence. The reaction should be manageable using a color pH indicator dye, and pacing the additions of isopropyl nitrite and neutralizing base solution at a metered rate which keeps the pH in the desired range of slightly alkaline. This is completely hypothetical, and has not been tested, nor can I find anything in the literature for guidance. However, it seems that the natural hydrolysis of the dimethylketazine could be exploited as described to form an azide, as the sole non volatile product, if the reaction proceeds in the correct pH range. If this hypothetical reaction proceeds with sufficient velocity is a big unknown, and if it will work at all as anticipated is also unknown. It may work fine or not at all.
It seems like it would work. So that makes this hypothetical experiment intriguing, especially if it is novel, when it doesn't seem like somebody else should not have thought of this possible? reaction before. I would have looked it up in the "Journal of Experiments that Seemed like they might work but Failed" but I haven't been able to locate that huge compendium encyclopedic work anywhere.

An interesting observation which I would make is that dimethylketazine could find usefulness as a sort of buffer in the orginal Hodgkinson reaction scheme using a neutral hydrazine salt being gradually reacted with an alkali nitrite, because as that reaction becomes acidic it would tend to tie up the hydrazine and quench the reaction, but the presence of dimethylketazine would tend to regulate that falling pH by additional hydrazine being freed by the increasing acidity due to hydrolysis of the dimethylketazine. This suggests it may be possible that both the original Hodgkinson reaction scheme, and the variation contemplated using dimethylketazine as the hydrazine source, might be possible to carried out in mixture as a system, where the kinetics would favor the formation of azide.

For a possible color pH indicator I am thinking bromothymol blue would be about right




Thanks to gsd for the following article (attached)
STUDIES ON HYDRAZINE. THE HYDROLYSIS OF DIMETHYLKETAZINE AND THE EQUILIBRIUM BETWEEN HYDRAZINE AND ACETONE
E. C. Gilbert
J. Am. Chem. Soc., 1929, 51 (11), pp 3394–3409
DOI: 10.1021/ja01386a032
Publication Date: November 1929



Attachment: STUDIES ON HYDRAZINE.pdf (933kB)
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[Edited on 21-4-2013 by Rosco Bodine]

hydrazidocarbamoyl azide / hydrazodicarbonazide / Hydrazinodicarbonic Acid Diazide

Quote: Originally posted by Bot0nist

Nice! Its is quite powerfull, huh? EM makes me nervous. I biult a steel impact test mechanism, and am always startled by how loud just a few mg of sensitive HE is. really puts it in perspective...

more regarding Biurea / hydrazodicarbonamide

Other references are found regarding the use of Biurea as a precursor for azides, and oxidation by hypochlorite is one method. Nitrosation by HNO2 is another. Carbamoyl azide is an intermediate product which is further hydrolyzed to hydrazoic acid. This is interesting because it occurs the hypochlorite oxidation occurs in a reaction system that is alkaline, which increases the solubility of the biurea, and which favors hydrolysis of the carbamoyl azide, and which favors neutralization of the hydrazoic acid as either its sodium or ammonium salt. Urea is a byproduct of the hydrolysis of the carbamoyl azide. The nitrosation of the biurea in aqueous NaOH may also be possible using isopropyl nitrite, although no references for this have been found.

(from earlier discussion, related)
http://www.sciencemadness.org/talk/viewthread.php?tid=1987&a...

http://www.sciencemadness.org/talk/viewthread.php?tid=6729&a...





Attachment: Darapsky Journal fur praktische Chemie.pdf (1.6MB)
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[Edited on 23-4-2013 by Rosco Bodine]

Quote: Originally posted by plante1999

Today I made a very tiny amount of silver azide, mostly to test my newly made hydrazine sulphate. I made a 50 ml solution of silver nitrite at 60 C and mixed it with 30 ml of a dilute hydrazine sulphate solution. After a minute, a flocculent precipitate formed. I filtered and too a very tiny sample of the wet azide on a steel sheet. Maybe a mg. Then I lets it dry, and heated with a match. I eard a very loud pop sound. I was amazed by the sound made from a such tiny amount of material. I then poured hot sodium nitrite solution on the azide to decompose it, washed all my glass and stored them. Hopefully this is of interest to someone.

Inorganic Azides

Inorganic Azides Solubility Chart


Hydrazoic Acid and Its Inorganic Derivatives.
L. F. Audrieth
Chem. Rev., 1934, 15 (2), pp 169–224
(attached)

Synthesis 26 and 27 from Inorganic Syntheses Vol. 1 (attached)

Synthesis 40 from Inorganic Syntheses Vol. 2 (attached)

Energetic Materials Physics and Chemistry of the Inorganic Azides, Fair (attached)

Attachment: Hydrazoic Acid and Its Inorganic Derivatives Audrieth Chem. Rev. 1934.pdf (812kB)
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Attachment: Synthesis 26 and 27 from Inorganic Synthesis - Volume 1.pdf (538kB)
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[Edited on 25-4-2013 by Rosco Bodine]

Staudinger Azide Patent DE273667

Here is an interesting idea related to the patent DE273667 which describes use of a nitrosamine as the reagent for diazotization / nitrosation of hydrazine to form an azide.

http://www.sciencemadness.org/talk/viewthread.php?tid=3453&a...

Thanks to Boffis for translation of the Staudinger Azide patent. I changed the formatting slightly to fit it on a single page and made a pdf for it too. (attached)

Urbanski 3 has a writeup on R-salt that provides useful information about the hydrolytic properties (attached)

Here also is an R-salt synthesis which I am not certain but I don't recall being posted before. From Journal of the Chemical Society 1889.



This idea of possible usefulness of R-salt as a nitrosation reagent is not a new idea for me. On the preceding page where I was mentioning again the Hodgkinson patent
http://www.sciencemadness.org/talk/viewthread.php?tid=1987&a...
towards the bottom of that post I mentioned a discussion a decade ago at the old newsgroup alt.engr.explosives, and linked a part of that discussion which was much more extensive. Near the very end of that thread I brought up the Staudinger patent which I referenced by the patent number and the use of a nitrosamine, and speculated that R-salt may also work. So this is a review here a decade later with additional references and translations for benefit. Here I will link that old newsgroup conversation, which was mostly between PHILOU Zrealone and myself. The relevant post is the third post up from the bottom of the page
http://alt.engr.explosives.narkive.com/sJmT2yCp/interesting-...
An excerpt pdf showing the relevant post is attached.
So this discussion and review of azides has come full circle over 10 years. There's the deja vu. There is no "re" in research without a little deja vu.

Attachment: DE273667 Staudinger Azide from nitrosamine and hydrazine patent.pdf (104kB)
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Attachment: R-salt preparation JCS.pdf (164kB)
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Attachment: excerpt from Interesting Azide Patents ( circa 1919 ) - page 5.pdf (18kB)
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http://www.youtube.com/watch?v=LjRuVehaXJ4

<iframe sandbox width="640" height="480" src="http://www.youtube.com/embed/LjRuVehaXJ4" frameborder="0" allowfullscreen></iframe>

[Edited on 27-4-2013 by Rosco Bodine]

Tough nut to crack is right.

They are a intriguing field to study, and provide unique initiating property's .
You comment about the sensitivity of Agn3, was it related to impact, friction, of photo-sensitivities? It was my understanding it is almost par with LA in power and less sensitive to the hammer drop. Urbanski #3 /pg #184 last paragraphs : state the Agn3 is less sensitive to the drop v.s LA. Also the hammer drop needed to initiate is 5x more than Merc-Fulm.
My assumption is the photo sensitivities you speak of in terms of dangers . I dont recall however finding the friction ratings of the material in comparison. Do you have some references to this aside from urbanski?

Also, Is the sol. of hno3, and Nano2 only needed in small amounts to kill the azide left in the waste wash? I was assuming that a 100ml sol. of 15% hno3, 8%nano2 would be more than effective to make the waste liquor(800ml) safe to dispose of . Is this a fair assumption ?
Also thanks for the in-site on the Nan3 being a fumigant for soils , I wasnt aware of that . good to know , though.

[Edited on 30-4-2013 by pjig]

Wow thanks.

What about Magnesium azide ? does aluminum or titanium azides exist ? if so may i know little about it I think elemental is good.

If lithium azide was elemental decomposition, it would have been great, lithium alone could have burned by oxygen to form the second most exothermic reaction in all of chemistry

memo for Dr. Klapoetke and his team

Quote: Originally posted by Rosco Bodine

Here's an obscure "carbonic" azide that would seem to qualify as a "green initiator" known by three slightly different names. Searches for this compound turn up very little information. hydrazidocarbamoyl azide / hydrazodicarbonazide / Hydrazinodicarbonic Acid Diazide Also described on page 2 of the pdf Carbamoyl Azides (attached)

Quote: Originally posted by bismuthate

Could I please get some information on bismuth triazide I could only find a paragraph about it. For example I know that it forms complexs however I haven't found out what it will Form a complex with. I wonder if anyone has ever been brave (or stupid) enough to make polonium azide.

Azides from secondary nitrosamines

Quote: Originally posted by woelen

I have some hydroxylammonium salts (the chloride and sulfate), but with these it is very hard to obtain the azide. The reason for this is that the solubility of the azide is not much different than that of the chloride or sulfate and the sodium salts also do not differ very much in their solubility. The reason why I could make NH4N3 easily is because 1) NH4N3 is much less soluble than NaN3, NH4NO3 and NaNO3 near 0 degrees Centigrade. 2) NH4N3 is not hygroscopic Both advantages do not hold for the hydroxylammonium salt. Probably another solvent than water is needed, but there are not that many solvents which dissolve NaN3 and hydroxylammonium salts easily, while hydroxylammonium azide does not dissolve well.

Silver azide and hydroxylammonium chloride

Lead azide and PETN ina copper tube

Quote: Originally posted by PHILOU Zrealone

Cu is not compatible with azides because Cu azide is very sensitive.

Airbag propellant question

After a lot of sawing I was able to get into an old airbag gas generation unit. I have a question for somebody who has gotten the NaN3 seperated from the oxidiser contained in the pellets. I have looked at some of the threads here and other places and they all seem to say the pellets were black. These are green. It is from a 2003 model ford from the steering wheel unit. Could this be something else newer and not NaN3? There actually is not a lot of information out there on this subject and I've read what's available so any help would be appreciated. There was only 45g and other people have said that they got upto 90g What could the oxidiser be that is green? The Boron potassium nitrate was in a separate little compartment and easily seperated.the green substance seems insoluble in water so if there is azide it should be easy to reclaim via filtration and evaporation of the water, and provided there is nothing else water soluble I should get back reasonably pure NaN3.