spong - 18-10-2010 at 23:51
I wasn't sure if this would work but I found a fridge repairman who gave me about 6ft of 6mm copper tubing for free so I thought I'd have a crack.
The setup was basically a deep fryer with a flask for boiling acetone in, a funnel to add it as it boiled away, a thermometer adapter connected to 6mm
copper tubing. The copper tube would around the burner of the BBQ and then down into a condenser with flask for unreacted acetone at the bottom. The
ketene would then be bubbled through a flask of water, this was only a trial run so I used water, any change in acidity would indicate it's working.
Boiling flask + copper tube:
Condenser and flask for bubbling, the outlet was led through more water in a measuring cylinder in case and ketene escaped the first flask (none did)
Flame on 
The copper tube stayed red hot, the burner easily supplied enough
heat, before the next run I'm going to straighten the tube and make it fit the shape of the burner better:
Smoke exiting the copper tube into the condenser:
Filling the flask at the bottom:
Full:
I put the acetone flask into some hot water to keep the ketene from dissolving, apparently it's very soluble in acetone. This water was changed as it
cooled down. In the next run I'll have a hotplate here:
After a while the water turned cloudy, I stopped here and took the ph of the water, acidic It didn't smell that much like acetic acid, it had this stinky
odour similar to that of the flammable gas leaving the setup:
The condensed acetone had taken on a yellow colour, it was dumped back into the funnel for the next run:
The results. There was also a small amount of water that had been sucked back into the tube, I saved this separately, hoping it might have got enough
ketene to form acetic anhydride:
1ml of the cloudy water/acetic acid from the large flask was titrated very, very roughly with NaHCO3, giving a rough concentration of 0.35 mol/l
acetic acid.
Once I can get glacial acetic acid I'll have a shot at making anhydride 
hissingnoise - 19-10-2010 at 06:39
Copper tubing won't stand up to strong heating for very long . . .
Hard glass tubing would be better!
http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0330
not_important - 19-10-2010 at 09:28
There's several journal papers on ketene production using copper tubes, I believe that inmost if not all of them the copper tube was driven into a
slightly larger steel pipe to protect the copper against air oxidation. Cheaper and much more rugged than glass, which is a good thing when working
with ketene.
Sedit - 19-10-2010 at 13:45
Copper also aids in stabilizing ketene to increase yeilds. I was going to try to attempt something just like this before I got my new job which took
up ALL my time but now that im laid off I have some free time. Since you didn't die or blow yourself up I might just have a go at this as well. I already have a large amount of Copper tubing coiled to be placed over an
electric burner which I was going to wrap everything in Kaowool and then clay to increase the temperature enough to make ketene. IIRC temperatures as
low as 600C is enough to get it to work so I think its well within reach. My main interest is making butt loads of GAA for solvent use in electrolysis
experiments but the anhydride could fid quite a few uses as well I guess.
spong - 19-10-2010 at 17:16
Yeah the copper was oxidized quite a bit, if it becomes an issue I'll go out and get some thick steel brakeline tubing and run it through that, I
could pack it with sand too to get a more even heat over the copper. I was thinking about filling the copper with some kind of packing material but
the hole is just far too small.
I'm going to use a pressure equalized funnel next time, with this one I had to sit there constantly adjusting the stopcock and having spurts of far
too much acetone coming through, plus it was a teflon stopsock and they're just a pain to use. If I had another funnel I'd connect it to the bottom of
the condenser so the acetone could be recycled.
I'll also try to run more acetone through this time, even if the conversion isn't that high I'll be making a lot more ketene.
Yeah the hotplate idea sounds good sedit, if I were any good with electronics I'd have a try 
It'd be much safer than barbecuing a copper tube filled with acetone.
Sedit - 19-10-2010 at 17:27
No real need for electronic experience on this one as it can just be hard wired to the plug or sent thru a dimmer switch if you wish to adjust it. The
element is nothing more then a 1500w electric oven element. I designed it like this to minimize space and maximize reaction area. Uncoiled It is a
very long section of tube in an area only about half a foot in diameter.
Ketene still scares the shit out of me so more research needs to be done before I ever attempt it.
not_important - 19-10-2010 at 17:34
Ferrous alloys don't seem to work too well for ketene production, although copper is fine; thus steel tubing may reduce yields and/or show accelerated
carbonised gunk buildup.
spong - 19-10-2010 at 17:45
Hmm I'll have to hit the tip shop and look for an old stove
If I used an electric element I could mount the boiling flask above the reaction tube, that way the excess heat rising will boil the acetone and save
me using my deep fryer.
I didn't do much research at all for this, I should have but I was just bored and had a couple of hours to spare I still don't know what ketene smells like but I think if any is escaping you'll
know about it, not like CO or HCN to some extent.
Ohh I meant over the copper tube not_important, I could run the copper through a steel tube filled with sand and plugged at the ends with fiberglass
or something.
Sedit - 19-10-2010 at 17:54
I have never smelled it either but I always assumed it smells like vinegar and death.... I like the idea of mounting the setup over the element it
just gave me a rush of ideas that could make the entire seup little more then a cubic foot or so meaning it would be cool to make a mini Ketene plant
with a definite input of energy all localized to the single circuit attached to the element. What I like about the idea is the unit can be laid out so
that it starts to run as soon as the temperature required to form ketene is reached by raising or lowering the flask of Acetone accordingly.
Honestly there is no real need to look for an old stove since Hardware stores sell these and they are not very expensive. About 10-15$ at the most for
a 1500w which would me more then enough to achive the temperatures needed.
spong - 20-10-2010 at 01:12
Yeah the condenser could be mounted above the plate too and the receiving flask for unreacted acetone could sit higher up or with a thicker layer of
insulation as to just keep it hot but not boiling. You could build a little wooden frame around the hotplate to hold everything in place. The worst
thing is trying to bend the copper pipe and reshape it while it's running. You could just take temperatures at different spots and then build it so
the tube will lead into the flask at the perfect height.
I was thinking of using a 3 neck flask for the collector next time with a tube leading into the bottom of the flask with a valve, once it gets a bit
too full you could suck the acetone into another flask with a vacuum pump and pour it back then seal off the tube again. That way it could be heated
easily but still removed easily as well, a funnel would be best here but I don't have another 24/40 funnel and it would be difficult to heat.
Hopefully I can find a little portable stove at the tip shop for $5 or something, I'd pay through the nose at bunnings (hardware store).
