Sciencemadness Discussion Board

C2H2 without CaC2?

Fusionfire - 1-8-2011 at 01:40

What are the alternative synthesis routes for acetylene gas that do not involve calcium carbide?

I only require a small quantity of acetylene but I seem to be having difficulty sourcing acetylene or calcium carbide in less than commercial quantities in the UK.

Would you be able to make improvised CaC2 by sending high voltage electrical pulses through a mixture of carbon + calcium oxide in a borosilicate tube?

Megamarko94 - 1-8-2011 at 03:33

i dont know any other way of making acetylene..
and if you want to make CaC2 yourself you need temp. over 2000c* so i dont think that borosilicate tube will handle that temp.

Fusionfire - 1-8-2011 at 03:57

Quote: Originally posted by Megamarko94  
and if you want to make CaC2 yourself you need temp. over 2000c* so i dont think that borosilicate tube will handle that temp.


The highest temperatures will be at the arc points but I consider the container to be disposable after a few uses. A cheaper and more acceptable sacrificial vessel may be made from fire clay.

ScienceSquirrel - 1-8-2011 at 04:34

Thre are descriptions on the Internet of making small amounts of calcium carbide using a welder.
The best idea is to keep an eye on eBay, sometimes a few hundred grams comes up for a few pounds.
That lasts a long time for small experiments.

smuv - 1-8-2011 at 08:18

KOH/Ethanol vinyl chloride.

KOH/Ethanol ethylene bromide.

*probably*KOH/Ethanol ethylene chloride *haven't checked lit on this one*

Many other ways but these are the least brute force methods. Vapor phase methods allow acetylene to be made from many substrates, but these require high temps. Although, acetylene is very otc if you are willing to rent/buy the tank (or as ScienceSquirrel pointed out, buy CaC2).

Fusionfire - 1-8-2011 at 11:09

There's this seller in the Czech Republic:

http://www.ebay.co.uk/itm/Calcium-Carbide-Stones-Carbide-Lam...

But given that both his photos use Wikipedia's pictures, I am suspicious.

Mailinmypocket - 1-8-2011 at 13:26

I have actually bought from this seller very recently, it was cheap and shipping was surprisingly also cheap... Sounded too good to he true but... I got my stuff wrapped tightly in plastic wrap and in a zip lock type bag... Big chunks though... Get your hammer ready...took 6 days to receive and I'm in Ontario, Canada ..

I checked his feedback before buying and it's very positive btw..

Fusionfire - 1-8-2011 at 14:00

OK thanks for letting me know, I'll buy some CaC2 from him rather than make my own by electric discharge...for now ;). A few hundred grams is plenty to make silver acetylide - too costly to make in any large quantity!

What I like about electric discharge through CaO + C is that not only are the raw materials dirt cheap, you don't have to fiddle about to get pure CaC2 if you're just after acetylene - just add water :D

The WiZard is In - 2-8-2011 at 11:53

Quote: Originally posted by Fusionfire  
What are the alternative synthesis routes for acetylene gas that do not involve calcium carbide?


There dobe 'bout 6, however, I don't think you will be
able to use them.

Took me The Analogue Guy 2 minutes looking a book
to find them. A digital person using
www.justfuckinggoogleit.com could probable do it faster.

I found a 977 page book on acetylene among others searching
online.

Otter - 5-8-2011 at 19:54

Quote: Originally posted by Fusionfire  
What are the alternative synthesis routes for acetylene gas that do not involve calcium carbide?

I only require a small quantity of acetylene but I seem to be having difficulty sourcing acetylene or calcium carbide in less than commercial quantities in the UK.

Would you be able to make improvised CaC2 by sending high voltage electrical pulses through a mixture of carbon + calcium oxide in a borosilicate tube?


What you can try is to react 1,2 dichloroethane with sodium amide. 1 equivalent of 1,2 dichloroethane will need 2 equivalents of sodium amide.

However sodium amide is incredibly reactive, it will definitely react with moisture in the air as the amides convert to ammonia by deprotonating water.

So many gases are tricky to work with.

Best stick with CaC2 and water. :)

497 - 9-8-2011 at 04:09

The alternative that looked most interesting to me was microwave induced plasma pyrolysis of methane (maybe mixed with inert gas). I read a very informative paper on it, which I don't have a link to, but it shouldn't be too tough to find. They found that rapid cooling was critical to avoid the decomposition of the acetylene. They devised a surprisingly simple venturi cooler system that was able to achieve cooling at 10 to the 5th K/second and subsequently yielded acetylene at an efficiency competitative with commercial production at the time. A microwave oven transformer could yield a hell of a lot of acetylene if the experiment is repeatable. More accessable alkanes like propane may also give yields..

Fantasma4500 - 19-1-2013 at 08:59

i have thought about making CaC2 from when you decompose calcium acetate into acetone, it undergoes a state where its liquid..
adding carbon to it at that point might work.. but i didnt have any luck with it yet.. somehow it apparently is capable of going into CaCO3 or CaO..

otherwise just go on ebay.de and search ''wühlmausgas''

http://www.ebay.de/sch/i.html?_nkw=w%C3%BChlmausgas&_sac...

nora_summers - 19-1-2013 at 22:47

Can you get pure calcium metal? Maybe you can grind it up with carbon powder and then heat it to form calcium carbide.

Random - 20-1-2013 at 04:59

Quote: Originally posted by nora_summers  
Can you get pure calcium metal? Maybe you can grind it up with carbon powder and then heat it to form calcium carbide.

You would need very high temperatures, much easier to obtain it than to make it.

franklyn - 20-1-2013 at 20:35

• You can buy small amounts of CaC2 on ebay for not too much money
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=15098...

• Acetylene (ethene) is made by warming Chloroform with Silver powder
2 HCCl3 + 6 Ag => 6 AgCl + C2H2
The silver is reconstituted by heating the AgCl with a solution of formaldehyde
and a few drops of alkali, or with glucose or sugar and alkali, metallic silver is
obtained in a finely divided state again.

• Acetylene is also obtainerd by heating Tetrachloroethane with Zinc
Cl2CH.CHCl2 + 2 Zn => 2 ZnCl2 + C2H2

• It's also derived from Dichloroethylene and Sodium metal
ClCH:CHCl + 2 Na => 2 NaCl + C2H2

• From Propargyl Aldehyde ( Propiolaldehyde ) and Sodium Hydroxide
CHΞC-CHO + NaOH => HCOONa + C2H2
Propargyl Aldehyde can be made by dehydrating Propargyl alcohol with H2SO4
www.orgsyn.org/orgsyn/prep.asp?prep=cv4p0813

• Acetylene is electrolytically formed from electrolysis of molten Fumaric acid
(287 ºC) or its sodium salt, and also from it's water soluble isomer called
Maleic acid which melts at 138 ºC, or from other unsaturated dibasic acids.
C2H2(COOH)2 => 2 CO2 + H2 + C2H2


A Dictionary of Applied Chemistry vol I , 1912 ( see page 25 )
http://books.google.com/books?id=vb8GAQAAIAAJ
A Dictionary of Applied Chemistry vol I , 1921 ( see page 39 )
http://books.google.com/books?id=MAA5AAAAIAAJ

Acetylene, The Principles Of Its Generation And Use
http://books.google.com/books?id=EFjkAAAAMAAJ , 1903
www.gutenberg.org/ebooks/8144 , 1909
http://archive.org/details/cu31924031240850 , 1910
click " All Files: HTTPS " at left side for download options

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Experimental
http://www.sciencemadness.org/talk/viewthread.php?tid=13144#...

Related Thread
http://www.sciencemadness.org/talk/viewthread.php?tid=2492

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[Edited on 21-1-2013 by franklyn]

IrC - 21-1-2013 at 04:08

Quote: Originally posted by Fusionfire  
What I like about electric discharge through CaO + C is that not only are the raw materials dirt cheap, you don't have to fiddle about to get pure CaC2 if you're just after acetylene - just add water :D


I would be mindful of the fact if this reaction has exposure to air, nitrogen will be combined to form a percentage of Calcium Cyanamide. Probably Co as well. Chemistry is not my specialty so one of the experts may want to comment on my thoughts. Also I have to wonder if Calcium Cyanide would not also be yet another byproduct.

http://en.wikipedia.org/wiki/Frank%E2%80%93Caro_process

http://portal.acs.org/portal/acs/corg/content?_nfpb=true&...