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Author: Subject: Methyl Acetylides
Axt
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[*] posted on 27-9-2004 at 22:42
Methyl Acetylides


Something thats been sitting under everyones noses, yet hasn't made mention. MAPP gas (methyl acetylene - propyne) is more readily available then acetylene and will also form acetylides with silver, maybe the others as well but I havnt seen any mention of the methyl acetylides before, maybe MAPP wasnt commonly used back in the days of Fedoroff etc.. Silver methyl acetylide (SMA) can be made by bubbling MAPP gas through a silver nitrate solution.

<center><img src="http://www.sciencemadness.org/scipics/axt/silvermethylacetylide.jpg"></center>
5g AgNO3 was dissolved into 75ml distilled water, into this was bubbled MAPP, within minutes the solution had turned white with a large crop of crystals, was filtered and dried.

<center><img src="http://www.sciencemadness.org/scipics/axt/smapics.jpg"></center>

On ignition small amounts of SMA explode with a thump, flame and thick cloud of black smoke.

<center><img src="http://www.sciencemadness.org/scipics/axt/smaignite.jpg">
<a href="http://geocities.com/roguemovies7/">MOVIE AVAILABLE</a></center><br>

[Edited on 9-12-2005 by Axt]
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Axt
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[*] posted on 28-9-2004 at 01:26


Sorry, methyl acetylene - <i>propyne</i> should be <i>propadiene</i>, propyne is another name for methyl acetylene.
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JohnWW
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[*] posted on 28-9-2004 at 01:43


You seem to have got them mixed up. Propyne, or methylacetylene, C3H4, is H-C(triplebond)C-CH3. It is isomeric with propadiene, or allene, H2C=C=CH2.

BTW How come propyne is "more readily available than acetylene"? In view of the manner in which acetylene can be made on an industrial scale via CaC2 by reaction of Ca metal, or of CaO or CaCO3, with carbon, I would have thought the opposite.

John W.
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Axt
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[*] posted on 28-9-2004 at 02:00


Quote:
Originally posted by JohnWW
You seem to have got them mixed up. Propyne, or methylacetylene, C3H4, is H-C(triplebond)C-CH3. It is isomeric with propadiene, or allene, H2C=C=CH2.

Errr yeh as I just said. I assume the propadiene is formed as a byproduct on forming MA.
Quote:
BTW How come propyne is "more readily available than acetylene"?

Because we (or at least I) arn't talking about industry, Im talking about walking into a hardware store and buying a bottle of gas, without the need, hastle or cost of hiring a whole tank of acetylene. MAPP is much more readily available to the common man.<br>

[Edited on 4-11-2007 by Axt]
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[*] posted on 28-9-2004 at 09:50


Quote:

BTW How come propyne is "more readily available than acetylene"? In view of the manner in which acetylene can be made on an industrial scale via CaC2 by reaction of Ca metal, or of CaO or CaCO3, with carbon, I would have thought the opposite.


Making acetylene through CaC2 is very uneconomical because of the huge energy cost for producing CaC2. Therefore this method has been largely abandoned by the industry. But let's keep this on topic and prevent another I-know-more-than-you showoff, shall we?

[Edited on 28-9-2004 by vulture]




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[*] posted on 28-9-2004 at 16:23
Im dumb


Ok, excuse my stupidness but how would you make a silver nitrate solution.
Iv never even made ng.

Thanks




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The_Davster
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[*] posted on 28-9-2004 at 16:50


Fitting title tomthumb:mad:

A solution is what results when a solute is disolved in a solvent.
In this case the solute is silver nitrate and the solvent is water.
So you just dissolve silver nitrate in water.
It was even stated in the post "5g AgNO3 was dissolved into 75ml distilled water", guess what that makes? Thats right, a solution.

jeez:mad:


EDIT: Axt; Did you weigh your yield?

[Edited on 29-9-2004 by rogue chemist]
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Axt
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[*] posted on 28-9-2004 at 17:45


No, I never weighed the yield, but I expect it depends more on your ability to get it out filter & dry it without loss, as it should go to near 100% (It wont create a double salt will it??).

Drop test was 0-5cm (same as acetone peroxide). Though it only fires after being struck numerous times at that height. 10-15 to guarantee first hit detonation. This is due to it being a fine powder, has to have any "give" pushed out of it before it will fire. Need a lighter weight on the rig to get decent results on the sensitive primaries.
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[*] posted on 28-9-2004 at 18:05


Yes, that was why I was wondering if you knew the yield, to calculate if there was a possibility of a double salt.

I hope to try this in the near future once I get some MAPP gas. I always wanted to try acetylides but was never able to get calcum carbide without huge hazmat charges.

Any tests on what it takes for silver methyl acetylide to DDT yet?

When I go to get MAPP, does that attachment on your bottle come with it, or does it cost extra? Thanks
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[*] posted on 28-9-2004 at 19:38


Quote:
Any tests on what it takes for silver methyl acetylide to DDT yet?


Nup

Quote:
When I go to get MAPP, does that attachment on your bottle come with it, or does it cost extra?


It'll cost extra, I have a couple and I think both were over $50, then $20 for the gas! (AUS $'s). Make sure you can easily add a tube to it, for some its not that easy without leaks.
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[*] posted on 28-9-2004 at 21:38


This is a bit off-topic, but the other major industrial process for making acetylene is by heating CH4, usually from natural gas, at 1,500ÂșC briefly (0.1 to 0.01 sec.): 2CH4 --> C2H2 + 3H2. This is obviously a lot quicker and requiring less energy (in terms of Ca reduction) than the CaC2 method, although the CH4 raw material may in the future be in short supply, and the C2H2 has to be separated from the H2 byproduct e.g. by gas chromatography or liquefaction.

As for methylacetylene, there do not appear to be any methods for preparing it directly or from a precursor 3-carbon compound, and without being mixed with allene (propadiene). The only methods appear to be from acetylene by adding a CH3, e.g. by using just enough NaNH2 and CH3Br with C2H2 for monomethylation (dimethylation can also occur).

A reference I have, T.W. Solomons' Organic Chemistry, says that silver (I) alkylacetylides, as an insoluble covalent compound, can be made by bubbling or mixing the alkylacetylene into an aqueous solution of ammoniacal silver hydroxide, [Ag(NH3)2]OH, with NH3 byproduct. Cu(I) acetylides can be made in the same way. The reaction is a qualitative test for terminal alkynes, and a method for separating terminal alkynes from alkynes in which the triple bond is internal.

John W.
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[*] posted on 29-9-2004 at 19:46


Well, I had a go at it tonight.
2g silver was dissolved in 2.5mL 70% nitric(yes I know thats a huge excess) and once disolved the volume was increased to 40mL by addition of distilled water. Propyne was then bubbled through.

I was intending to do this as an analytical experiment to figure out if SMA formed a double salt but I made a few very stupid mistakes.
-I did not wait long enough for the silver to dissolve
-I did not bubble propyne through long enough, evidenced by after filtering out the SMA, adding NaCl to the filtrate caused silver chloride to precipitate.

Also, Axt, I only paid 10$(CDN) for my pound of propyne:cool:, but that is probally because I am in a province with a lot of petrochemical resources/industries. I also managed to get around paying for a 50$ adaptor by just using the cheap burner head from my propane torch, unscrewing the flame adjuster off and attaching tubing to what was left of the burner assembly.

And finally, Axt, did your propyne smell terrible, mine did:(, I was expecting it to smell something like propane which I find has a semi-pleasant smell.

I will definatly be repeating this experiment, so I can determine if SMA forms a double salt.



[Edited on 30-9-2004 by rogue chemist]
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Axt
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[*] posted on 29-9-2004 at 23:31


Quote:
Originally posted by rogue chemist
And finally, Axt, did your propyne smell terrible, mine did:(, I was expecting it to smell something like propane which I find has a semi-pleasant smell.

I believe the the last P in MAPP is "petroleum gas" (LPG). Probably has additives to give it the awful smell.
Quote:
Also, Axt, I only paid 10$(CDN) for my pound of propyne

Same "benzomatic" cylinder? I think they would be the most common in N. America, US company. The benzomatic plastic torches wont work for feeding gas. I had to buy the brass one shown, which could have the "air inlet" screwed off.

Anyway, all attempts to make an acetylide from cupric salts (sulphate,TACN,hydroxide) and Ni(NH4)2(S2O4)2 have failed, amminated or not.<br>
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[*] posted on 30-9-2004 at 01:47


Did you try Cu I (cuprous)? IIRC this works better with normal acetylene too - and is more stable.
By failing I presume no precipitate could be found?




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[*] posted on 30-9-2004 at 12:25


rouge chemist, foul smelling components are typically present in C2H2 made from CaC2. The latter also contains CaP forming phosphine in contact with water.

It would not be a surprise if C2H2 made by other processes has foulsmelling additives too, to distinguish it from other gases (and give it the "traditional C2H2 smell) and make leaks noticable . C2H2 has a very wide explosion range in air and is very dangerous because of that. But not under this conditions.

It is great fun to drop a few pieces of CaC2 into water while keepiing igniting the gas bubbles forming, especially if soap is added :) the soot makes the flames very bright!

/rickard
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[*] posted on 30-9-2004 at 16:11
Some results


My SMA dried into large plates on the filter paper that were grey unlike the SMA after it first precipitated. I do not like how it created those plates as they must be broken up in order to use the primary, which is always nerve wracking.
Does anyone have an idea on why SMA darkens after a while?

SMA does not seem to DDT that easily. Into a 3mm diameter straw was pressed 10mm column of lightly pressed SMA. This was then taped to a nickel and electrically ignited under some sand. I was rewarded with a small bang, obviously not a detonation, too quiet, and the nickel was not deformed in the slightest, just blackened by silver. I hope to try again with a better casing and possibly a bit more SMA.
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[*] posted on 30-9-2004 at 16:24


Probably darkens from photosensitivity to light, like many silver compounds. As the light strikes it the silver is reduced to the free element and in turn probably releases something like CH3CC-CCCH3



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Axt
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[*] posted on 1-10-2004 at 18:20


Quote:
Originally posted by chemoleo
Did you try Cu I (cuprous)?


I had a half-arsed attempt. Dissolved CuO in HCl, then Cu into that until clear. Using varying amounts of ammonia (from none to a lot) I couldnt get an explosive precip. If ammonia was added until the purple complex (from residual cupric) just started to form, bubbling the MAPP resulted in a non-explosive mass of yellowy-green precip. Cu(OH)Cl ? Whatever the case, cuprous isn't easy.

Below is the result 0.1g Ag salt lightly pressed in a .22 Khornet case, doesnt mean much but at best looks to be a weak detonation.

<center><img src="http://www.sciencemadness.org/scipics/axt/smacasing.jpg"></center>

[Edited on 9-12-2005 by Axt]
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[*] posted on 1-10-2004 at 19:01


Axt, what are the benzomatic plastic torches? My gas cylinder of propyne is "BernzOmatic" brand and is brass.

I attached a picture of the cylinder and my way around paying for a 50$ attachment; a disposable pipette withthe end removed, taped to the main body of the propane burner attachment. Coincidently, the other end of the pipette happens to fit perfectly into the inside of a piece of my glass tubing.:)

EDIT: "burnzOmatic"changed to "BernzOmatic":P

[Edited on 2-10-2004 by rogue chemist]

methylacetylene.bmp - 900kB
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Axt
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[*] posted on 1-10-2004 at 19:27


OK, now that I look mine is "bernzomatic" as well, stange that I've always read it at "benzomatic", but then, your reading it as "burnzomatic" :D. Sounds like yours is a different formulation to me, I dont know what MPS gas is.

<center><img src="http://www.sciencemadness.org/scipics/axt/torches.jpg"></center>

[Edited on 9-12-2005 by Axt]
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[*] posted on 1-10-2004 at 19:39


Axt ,

Have you tried acidifying the AgNO3 solution with nitric acid , to see if you
get the double salt ? I'll check some references I have for the usual acetylide
double salt and get back on this . The
reaction is pH dependent and different
products may result for the usual acetylide , so this reaction may be similar .
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[*] posted on 1-10-2004 at 19:43


To quote the label;
"MPS* GAS
Methylacetylene Propadiene, Stabilized"
56% CAS 68476-85-7
44% CAS 59355-75-8

I think is about the same thing as MAPP but with a stabilizer of sorts. I do get the same product as you but mine has absolutly no noticable flame once ignited, just the cloud of silver dust( Damn my fingertips are black:P)

EDIT: Rosco when I made mine I disolved my silver in an (large)excess of nitric acid then bubbled gas through and my product was very similar to Axt's

EDIT2: googled the CAS numbers and found out it is 44% MAPP and 56% "A fuel mixture of propane, propylene, butanes & butylenes"



[Edited on 2-10-2004 by rogue chemist]
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Axt
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[*] posted on 1-10-2004 at 19:54


Rosco, No I havn't, and I wont get a chance to try now, won't make it home again for a couple months. Maybe the strange greeny precip was a double salt of the chloride, it only formed in mass when MAPP was bubbled through it. It was completely non-energetic, but it gave a brilliant blue when hit with the flame.

EDIT: RC, thats sounds like the same stuff, 44% MA-P 56% P --> MAPP.

[Edited on 2-10-2004 by Axt]
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[*] posted on 1-10-2004 at 19:57


US2483440 describes some of the different concentrations and pH conditions which produce quite different
compounds . The concentration of the
solution of AgNO3 should be kept below 10% and other references say slightly acid , IIRC , in order to produce the
double salts . PATR may have some
information on these details .
See PATR vol. 1 page A-80

[Edited on 2-10-2004 by Rosco Bodine]
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[*] posted on 2-10-2004 at 01:50


Seems that the patent reference provided shows that straight AgNO3 should create the double salt, since HNO3 is created during the reaction. PATR mentions the ammonia soluton to give the straight acetylide.

It also says the high concentrations of AgNO3 will give higher complexes, that while non-explosive with the acetylide may be beneficial with the methyl acetylide as to even up the oxygen balance. Bloody expensive but it would be a good idea to try highly concentrated AgNO3 solutions.

The difference in weight of the SMA and the complex wouldnt be much, so you would have to create quite a batch to confirm any differences, but luckily the complex will weigh more, so if you achieve higher then theoretical yields its a near certainty that you have a complex.

PATR gives the cuprous chloride complex of acetylide as being non-explosive, so its possible that it was what I got with a simular solution.

[Edited on 2-10-2004 by Axt]
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