first encouraging ketenelamp experiment

[hypo]

1m of standard restistance wire (the expensive one for $2/roll) was coiled using a glassrod and attached to 2 pieces of thick copper wire. the copper wires were put through a rubber stopper and attached to a 220V variac. the rubber stopper was placed in the central neck of a 2-neck adapter which was placed on a RB with some acetone in it. on the other neck of the 2-neck adapter were placed 2 condensers in series, the upper one being cooled with water. the top of the upper condenser was attached to a pipette in order to bubble the formed gasses through water. the flask was heated until the acetone was refluxing from the upper condenser. the aparatus was left in this state for 5 min, then current was turned on. when the resistance wire started glowing red, gas was produced. the amount of gas produced was easily controlled by the amount of current. after about 5 min a strange smell was noticeable and the experimentor experienced a cough reflex. the experiment was stopped at this moment.

what do we learn from this?
- it's time to stop wasting Br2, S, PCl3 and other valuable chemicals.
- no need for special nichrome wire. standard resistance wire will do.
- no need for special apparatus ala vogel.
- heat seems not to be a big problem. the rubber stopper showed no signs of burning.
- the rate of ketene production is easily controllable
- ventillation seems to be a problem. either the apparatus had a leak or ketene is not as reactive as SO2.

this seems too easy to be true...

[LaBTop]

Giggle giggle. The bulk of the readers seem to miss something important happening here, hehhe. LT/
WISDOMwillWIN

[PrimoPyro]

Oh I loved the post, hypo and LaBTop. I am very enthusiastic about ketene usage. I myself have been thinking of experimenting with nanoscale ketene generation (<100mL MeAc) using a tube with a pair of 500W halogen replacement bulbs as the wire source, after removing the glass covering of course. I'm referring to bare wire.

If I can turn distilled water into glacial acetic acid, I will gleefully jump up and down with joy and sing a happy happy song, proving the experiment to be a success.  

In any case, hypo, thank you.    This post has added to my confidence that this procedure truly is clandestinely feasable. Great work!

                                                  PrimoPyro
The Water Will Be Your Only Mirror

[lugh]

You need to improve your sealing, keten is a highly toxic gas, about equal to phosgene    The maximum allowable long term exposure concentration is .5 ppm in the US, Germany and Switzerland. For short term exposure, it's 1-1.5 ppm. 25 ppm is generally lethal. Keten also forms explosive mixtures with air in the 5.5 to 18 vol % range. The liquid has a flash point of -107 C In case of fire, water or extinguishing powder should be used. By products of the pyrolysis of acetone are ethylene, carbon monoxide and methane. Purification may be accomplished by dimerization, followed by depolymerization.

[Osmium]

I'd rather try to absorb the ketene in an organic solvent due to solubility reasons, e.g. in acetic acid (doesn't have to be 100%). Also, everything not absorbed should be burned, can't hurt to use a slow stream of an inert gas, e.g. butane which will also help in combusting everything which comes through.
I'm not fat just horizontally disproportionate.

[terbium]

using a tube with a pair of 500W halogen replacement bulbs as the wire source
Since you seem to be going for the most expensive source of heating wire possible might I suggest platinum wire. Platinum wire should make your setup even more expensive than using large halogen bulbs. As for myself, I am cheap, I would just use the commonly available and inexpensive nichrome wire.

[PrimoPyro]

Uhh, expensive? I dropped a crate of them a week ago, and when picking them up I looked at them, and the price was like ~$4 for a pack of two. Where does one go to buy nichrome wire? My hardware store doesn't carry anything but copper wire and thin steel cable.

                                                 PrimoPyro
The Water Will Be Your Only Mirror

[blondie]

nichrome wire is available at hobby stores - they are used for fast (10 mins) recharging of nicad battery packs from a car/truck battery. they are about 3 feet in length (1 metre   ) - iirc you they are available in different lengths/sizes to match the batteries and correctly regulate the current.

[LaBTop]

Ehh, HYPO, you still alive??? (You did work in a glovebox or had at least an exhaust fan running? YES? ) LT/
WISDOMwillWIN

[terbium]

Where does one go to buy nichrome wire? My hardware store doesn't carry anything but copper wire and thin steel cable.
And they won't order it for you? You need to find a better hardware store. Or an electronics store should be able to order it. Most laboratory supply houses will also carry it.

If none of those places work for you then, even though they are a bit pricey, you could get it mailorder from here:

http://www.heatersplus.com/nichrome.htm

Or you could go to your favorite junkyard, surplus electronics, used appliance or Salvation Army store and recover it from a heating device.

http://www.howstuffworks.com/hair-dryer3.htm

[uemura]

Hi Osmium,
suppose you make the setup with Terbium nice idea with the nicr wire from fans. Should you head-up for AA, how to proceed. You said I'd rather try to absorb the ketene in an organic solvent due to solubility reasons, e.g. in acetic acid (doesn't have to be 100%). How to get out any AA from the mix? Carpe Diem

[Rhodium]

The boiling point of acetic anhydride is 139°C, while the boiling point of glacial acetic acid is 117°C. Slow fractional distillation should separate the two compounds, if in doubt - distill twice.

Large-scale ketene -> Acetic anhydride:

http://web.mit.edu/10.551/www/Archives/Homework00.2.pdf

[terbium]

Or set up an absorption train - a series of glacial acetic acid filled bottles. By the time ketene breaks through the last absorption bottle in the train the first bottle should be completely converted to anhydride. Remove the first bottle from the train and add a bottle of fresh GAA at the end of the train.

[hypo]

Ehh, HYPO, you still alive???

alive and well, thanks for asking  

another experiment was done, this time only one condensor, the ketene bubbled for some hours through commercial acetic acid and then through a bucket full with water (without moisture protection). volume increase about 10%. will tell you more after distilling. the plastic of the connectors on the outside of the lamp melted, but apart from that no problems with heat.

[hypo]

little update: volume increase was underestimated. volume increased from 200ml to 270ml or 35%. let's see how much of this is distilled acetone...

i like the idea of burning excess ketene. acquiring a burner should be easy, just the butane worries me somewhat.

the idea with the absorption train is great too. especially when you got some hectoliters of acetone to pyrolyse.    the only problem i see is that with each bottle, pressure inside the reaction increases, right?

uemura: why would you destroy a perfectly good fan when you can get 5m of resistance wire for $2.

another note: the only somewhat expensive part in this apparatus, the variac, is absolutely needed. it should really be infinitely variable, because very little current makes the difference between no ketene and lots of ketene. also the ketene production slowed down a little bit in the course of the experiment. the nice thing is that it can be stopped immediatly by turning a knob.

ooops... before i forget: what about freezing out the GAA from the mixture?

[PrimoPyro]

For a continuous absorption train setup, you could get/make a gas manifold with a stopcock at each appendage. I have seen nice glass ones at a noteable auction site. Close off a valve, replace the now full bottle, reopen the valve.

                                                   PrimoPyro
The Water Will Be Your Only Mirror

[uemura]

hypo!

your keten production setup is very promising. why would you destroy a perfectly good fan when you can get 5m of resistance wire for $2. Uemuras thought more of cannibalising a  broken heater or fan from the electro garbage place.    

What resistence did you wire have? The ones at www.conrad.com come with different resistances. From 28 Ohm to 100 Ohm per meter. Instead of a variac you could use a lab-power-supply (also not very expensive at conrad) and increase voltage to the point the wire start to glow.

Could you provide us with a picture or a drawing for your setup? Would be helpful. Carpe Diem

[hypo]

uemura, i sent you a picture of the ketenelamp at work to your hushmail address. the description of the wire should say something like "can be used as heating wire up to 1000°C".

[hypo]

hi, bees! help needed!

- is there an (preferably OTC) possibility to titrate a GAA/AA mixture?
- do acetone and AA react?
- can someone describe the smell of AA?

this is what happened until now: ketene was bubbled through commercial acetic acid, volume increased from 200 to 275 ml.

update: the resulting mixture was distilled. unfortunately the experimentator was not able to get clean fractions, so he took 3 broad fractions:
f1: 80°-120° - 170ml
f2: 120-129° - 70ml
f3: 129-140° - 30ml

all 3 fractions did not smell like pure GAA. they all had a sweetish smell somewhat reminding that of ketene itself. f2 and f3 where put in the freezer. f2 froze very fast and melted when taken out of the freezer. f3 did not freeze at all even after a full night in the freezer. no crystals, just a clear liquid.

somewhat disapointing. 30ml AA and not even pure   . from 70ml volume increase you could at least have expected 100ml AA. what happened?
 - the acetic acid had big amounts of water?
 - during workup acetic acid was destroyed?
 - the volume increase stem mainly from distilled acetone?
 - acetone reacted wit AA?

whatever it might be, setup v0.2 will definetly contain an acetone trap (like in vogel), consisting of a second set of condensor, 2-neck adapter and rb flask (in an ice bath). the ketene/methane/acetone mixture will enter the top of the condenser and the acetone will condense into the rb flask while the ketene/methane will go out of the second neck of the 2-neck adapter. this is not only necessary because the acetone might be a bitch to get out of the mixture, but this way you can bubble until the volume increases to a fixed value and then know the exact concentration of AA.

the gas will then be piped directly into a flame. it contains methane, so burning should be pretty complete.

if you read until here, what do you think?

[lugh]

In JACS 54 3427-31 (1932) it states by using a slight excess of keten, 20 cc of distillate gives 17 cc of AA (quantitatively), so your main problem is probably the purity of your keten. More data will be needed to determine the cause. Configuring the apparatus to conform with what is known to work would be the simplest solution. Have you looked at German Patent 403863 ?