hypo (Hive Bee)
02-22-02 14:03
No 271991
      first encouraging ketenelamp experiment  Bookmark   

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
(Daddy)
02-23-02 23:09
No 272641
      Re: first encouraging ketenelamp experiment  Bookmark   

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

WISDOMwillWIN
 
 
 
 
    PrimoPyro
(Hive Prodigy)
02-24-02 00:05
No 272657
      Re: first encouraging ketenelamp experiment  Bookmark   

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. blush

In any case, hypo, thank you. smile 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
(Moderator)
02-24-02 00:19
No 272662
      Re: first encouraging ketenelamp experiment  Bookmark   

You need to improve your sealing, keten is a highly toxic gas, about equal to phosgene frown 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
(Stoni's sexual toy)
02-24-02 01:36
No 272691
      Re: first encouraging ketenelamp experiment  Bookmark   

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
(Old P2P Cook)
02-24-02 03:56
No 272734
      Re: first encouraging ketenelamp experiment  Bookmark   

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
(Hive Prodigy)
02-24-02 04:07
No 272736
      Re: first encouraging ketenelamp experiment  Bookmark   

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
(Stranger)
02-24-02 07:44
No 272804
      Re: first encouraging ketenelamp experiment  Bookmark   

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 wink) - iirc you they are available in different lengths/sizes to match the batteries and correctly regulate the current.
 
 
 
 
    LaBTop
(Daddy)
02-24-02 07:49
No 272806
      Re: first encouraging ketenelamp experiment  Bookmark   

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

WISDOMwillWIN
 
 
 
 
    terbium
(Old P2P Cook)
02-24-02 08:29
No 272813
      Re: first encouraging ketenelamp experiment  Bookmark   

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
(Hive Photographer)
02-24-02 16:11
No 272891
      Re: first encouraging ketenelamp experiment  Bookmark   

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
(Chief Bee)
02-24-02 17:36
No 272915
      Re: first encouraging ketenelamp experiment  Bookmark   

The boiling point of acetic anhydride is 139C, while the boiling point of glacial acetic acid is 117C. 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
(Old P2P Cook)
02-24-02 19:55
No 272947
      Re: first encouraging ketenelamp experiment  Bookmark   

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
(Hive Bee)
02-24-02 22:54
No 273006
      Re: first encouraging ketenelamp experiment  Bookmark   


Ehh, HYPO, you still alive???




alive and well, thanks for asking smile

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
(Hive Bee)
02-25-02 10:37
No 273283
      Re: first encouraging ketenelamp experiment  Bookmark   

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. smile 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
(Hive Prodigy)
02-25-02 10:49
No 273286
      Re: first encouraging ketenelamp experiment  Bookmark   

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
(Hive Photographer)
02-26-02 11:46
No 273722
      Re: first encouraging ketenelamp experiment  Bookmark   

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. smile

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
(Hive Bee)
02-26-02 12:28
No 273735
      Re: first encouraging ketenelamp experiment  Bookmark   

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 1000C".
 
 
 
 
    hypo
(Hive Bee)
02-27-02 12:49
No 274228
      Re: first encouraging ketenelamp experiment  Bookmark   

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 frown. 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
(Moderator)
02-27-02 14:42
No 274278
      Re: first encouraging ketenelamp experiment  Bookmark   

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 ?
 
 
 
 
    foxy2
(Distinctive Doe)
02-27-02 14:47
No 274280
      Re: first encouraging ketenelamp experiment  Bookmark   

Here is some good information on purification
Patent US5264087
Patent US4737318
This is ok
Patent US4107002

here is a brute force method for acetic and propionic anhydrides
Patent US2872481
Patent US2160842

An interesting thought from above patents.
You could make acetic anhydride by refluxing GAA in a pressurized system while passing the reflux stream over a bed of silica gel.  You just need to design a pressureized refluxer(easier said than done), this would give you easy small batches of acetic anhydride. 
 
Other stuff
Patent US1915573
Patent US1815802

This could give you some ideas
http://www.chemeng.ed.ac.uk/~neilm/new/azeotope/AA.html
Who knows if acetic anhydride forms azeotropes

Make a Difference Donate Now!! (http://www.lp.org/drugwar/)
 
 
 
 
    hypo
(Hive Bee)
02-27-02 15:39
No 274289
      Re: first encouraging ketenelamp experiment  Bookmark   

thanks a lot! that's interesting reading material.

i especially like the fact that you probably can separate AA/GAA using a toluene/water system. let's see...

i'm also pretty much convinced that the volume increase came mainly from acetone vapors that were carried with the ketene.
 
 
 
 
    MMM
(Stranger)
03-01-02 04:41
No 275114
      Re: first encouraging ketenelamp experiment  Bookmark   

? Toluene/water system, if you are thinking of extracting AA into Toluene and the acetic acid into the water.  Consider the solubility of water in Toluene and the reaction of water with AA :(   Sorry.

Toluene forms azeotrope with water, BP 85C, 20%H2O

Swim had good recovery of AA by using refractionating column, initial distillation mixed with Acetic, then temp rose to proper 140C, the AA was then reused in next iteration with no problems.

MMM

When the day is bad,and life's a curse
CHEER UP!!! Tomorrow may be Worse!!
('HAGAR' Comic)
 
 
 
 
    foxy2
(Distinctive Doe)
03-01-02 05:36
No 275132
      Re: first encouraging ketenelamp experiment  Bookmark   

MMM
Read those patents

Make a Difference Donate Now!! (http://www.lp.org/drugwar/)
 
 
 
 
    hypo
(Hive Bee)
03-01-02 12:24
No 275257
      Re: first encouraging ketenelamp experiment  Bookmark   


Consider the solubility of water in Toluene and the reaction of water with AA :(   Sorry.




yep, i had the same considerations. but apparently AA reacts only slowly with water when cold. unfortunately fractionating is not a possibility right now.

btw:

- the acetone trap proved very useful (the collected acetone is really dirty (dark brown/red), what's that??).
- also it was noted that fast ketene bubbling is the way to go. this way you increase the keten/acetone ratio and the reaction is nicely exothermic (and you're finished sooner, of course). you probably can even notice 100% conversion, when the reaction is no longer exothermic.
- burning the excess ketene/CH4 worked good by piping the ketene in the flame of a camping cooker. good ventilation was still needed.

 
 
 
 
    Osmium
(Stoni's sexual toy)
03-01-02 13:00
No 275261
      Re: first encouraging ketenelamp experiment  Bookmark   

hypo, can you please measure the wire diameter and guesstimate the needed current?

I'm not fat just horizontally disproportionate.
 
 
 
 
    hypo
(Hive Bee)
03-01-02 19:18
No 275380
      Re: first encouraging ketenelamp experiment  Bookmark   

this data comes from the producer of the wire:

diameter: 0.5mm
resistance: 5.6ohm/m

another wire will be tested in the course of the weekend.

the variac was going at about 40%-45% of it's power on a 230V socket. i have no idea what that means and no ohm- or amperemeter is available
 
 
 
 
    hypo
(Hive Bee)
03-02-02 10:21
No 275698
      Re: first encouraging ketenelamp experiment  Bookmark   

every wire does not work frown

the cheap one made it for about 3 seconds before disintegration.
 
 
 
 
    uemura
(Hive Photographer)
03-02-02 10:33
No 275703
      Re: first encouraging ketenelamp experiment  Bookmark   

Hi hypo,

thanks for the pic you PM-ed Uemura. If you want, Uemura could upload it to have it available to all Hive bees.
Successful weekend!


Carpe Diem
 
 
 
 
    uemura
(Hive Photographer)
03-03-02 10:06
No 276141
      Re: first encouraging ketenelamp experiment  Bookmark   

On request by hypo Uemura loaded this one up.
every wire does not work    But this one does: (Copyright Hypo)


Carpe Diem
 
 
 
 
    Chromic
(Hive Addict)
03-03-02 19:29
No 276299
      Re: first encouraging ketenelamp experiment  Bookmark   

>can someone describe the smell of AA?

IIRC, smells similar to GAA but I've never really taken a close whiff of it.

>the resulting mixture was distilled. unfortunately the experimentator was
>not able to get clean fractions, so he took 3 broad fractions

Fractionally distilled? What length of a column did you use?

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

This could be dangerous and doesn't help the need for ventilllation. I suggest you run a length of tubing to out of your residence if you don't have a fumehood.

Btw, I love the simplicity of this. I read your post on version 2 a number of times, but for the life of me can't understand how the apparatus is arranged differently. I think I get version 1: you had a flask on a water bath connected to a claisen that has a wire running down in the centered hole then a water condenser on the offset hole using an gas adapter on the top piped to say a filter flask with GAA then the tubing vented out the window?

The cool thing is you could use a 600W dimmer and any 30 ohm length of nichrome wire (V=IR, P=IV... R=V^2/P, R=(120)^2/500W, R=28.8 ohm)... and everything is easy to find/adapt and OTC, well, except the wire... anyways, very cool.
 
 
 
 
    hypo
(Hive Bee)
03-03-02 20:17
No 276317
      Re: first encouraging ketenelamp experiment  Bookmark   


> IIRC, smells similar to GAA but I've never really taken a
> close whiff of it.

yes, it produces the same "stench" in the nose, but the "smell" is quite different. strangely sweetish. otoh, this could be some impurities?

> Fractionally distilled? What length of a column did you
> use?

no column was used. but the real problem was that the yield sucked. the second try, with less GAA, acetone trap and vivid bubbling gave a nice AA fraction at 138-140 even without column, a fraction from 119-138 (for reuse) and a somewhat mysterious yellow forerun in the range of 80-90 (trashed).



> This could be dangerous and doesn't help the need for
> ventilllation.

well, it worked. i think there is no great danger, as there is no oxygen in the aparatus. the problem with piping the excess ketene outside of your house is that better nobody catch you doing it! clandestine chemistry is one thing, producing a gas as toxic as a wargas another.

> I read your post on version 2 a number of times, but
> for the life of me can't understand how the apparatus is
> arranged differently.

you described the first one very well. now instead of piping the gas directly through GAA, it is piped into the top of another condensor, which sits in the center hole of another claisen which again sits on a rb flask, preferably sitting in an ice bath. the second arm of this claisen is connected to a gas adapter, which is connected via tubing to the washing bottle with GAA. this is necessary to catch the acetone that gets carried with the ketene/CH4 mixture and which is a bitch to get out. i don't know if stacking 2 condensors is as effective, but i know that this setup worked very well.

> and OTC, well, except the wire

the wire was bought in a big (european) electronics place. can't get more OTC than that.
 
 
 
 
    Chromic
(Hive Addict)
03-04-02 00:00
No 276397
      Re: first encouraging ketenelamp experiment  Bookmark   

I'm an OTC nut and this sounds like fun. I'd love to try this project someday, thank you for the explanations!
 
 
 
 
    lugh
(Moderator)
03-04-02 00:53
No 276416
      Re: first encouraging ketenelamp experiment  Bookmark   

This may bee helpful if it can bee found smile

The whole book (135 pages) is devoted to a worked example of how to design an entire plant for the production of Acetic Anhydride by thermal cracking of Acetone, and it includes Acetone Distillation Unit.

The manufacture of Acetic Acid, published by The Institution of Chemical Engineers, London. It was published in September 1961.
 
 
 
 
    MMM
(Newbee)
03-11-02 17:51
No 280676
      Re: first encouraging ketenelamp experiment  Bookmark   

I knew I had come across a calculator for nichrome wire sometime. smile Hehe, UTFSE by all means, but dont forget the everyday engines either, www.google.com is great.

http://www.wiretron.com/free.html

Nearly forgot, you'll need this too

http://www.wiretron.com/nicrdat.html

HTH somebee's experiments, MMM



When the day is bad,and life's a curse
CHEER UP!!! Tomorrow may be Worse!!
('HAGAR' Comic)
 
 
 
 
    Mountain_Girl
(Newbee)
03-12-02 07:27
No 281076
      Re: first encouraging ketenelamp experiment  Bookmark   

Hypo:

I echo Chromic's admiration for this project.

A bit of info on industrial AA distillation (from rctn of ketene with GAA) which may or may not be useful:

"Pure Anhydride Distillation

The raw anhydride can be distilled either continuously or discontinuously. In discontinuous distillation, three fractions are obtained:

Forerun (1 %) is about 40 % acetic acid; the rest consists of volatile liquids, particularly methyl acetate and acetone.
Middle run (about 10 %). Depending on the quality of the column, it contains 30 60 % acetic anhydride; the rest is acetic acid.
Pure Anhydride. Using discontinuous distillation at normal pressures, the purity of the anhydride cannot exceed 99 % (the remainder is acetic acid) because, at the still temperature required, a certain amount of decomposition occurs. These difficulties can be overcome by operating under reduced pressure.

For continuous distillation, two or three columns are used, depending on the required number of fractions (forerun and middle run are separated). The middle run portion is returned to the reactor as reagent acid. The residue of the distillation contains small amounts of tarry products and is worked up continuously in a Sambay evaporator."

 
 
 
 
    Acetyl
(Stranger)
04-12-02 07:47
No 295889
      second encouraging ketene lamp experiment  Bookmark   

I would like to say thanks to "hypo" for realizing that building a ketene lamp is easy, "rhodium" for making this place possible, and "chromic" for the idea of using a dimmer, "uemura" for posting the picture from hypo and Organic Synthesis for mentioning this method.

<two cents>

The production of heroin requires acetic anhydride and getting my hands on it has always seemed either too risky or nearly impossible until that message (not that I would ever make it, but that a FOAF is interested). So I went out and got:

- nichrome wire from a hobby store ($2) (~1.2m?, ~32swg?)
- multimeter from the automotive section in a department store ($10)
- 600W dimmer from a hardware store ($4)
- detachable "bullet" connectors from electronics store ($4)
- #5 rubber stopper, four screws, piece of wood, one two wire extension cord, one three wire extension cord, some glass / heating equipment / clamps.

I tested the wire with the multimeter, 26 ohms. That looked fine to me. Two screws were put through the #5 stopper. The screw tips are attached to the ends of the nichrome wire that was formed into a spiralling loop by carefully wrapping it around a glass rod. The ends of the screws are attached to the two-wire extension cord. The ends of that cord are crimped with the connectors, as are all the other connections. This is done so the whole thing can be easily taken apart, updated or whatever. One side is attached to a dimmer, the other to the 3-wire extension cord. The other contact of the dimmer is attached to the extension cord. The ground of the dimmer is attached to the ground of the extension cord. The dimmer is screwed onto the hunk of wood. This completes the pyrolysis thingy.

Everything else is set up like hypo described. Acetone is boiling in a flask on a water bath. Pyrolysis thingy in the central neck of a Claisen. Condenser on the other neck. Gas outlet adapter to some tubing going into the solvent, the excess fumes going out the window.

I learned the following:

1) it really was TRULY a COMPLETELY UNNERVING EXPERIENCE turning on the power to pyrolyze the acetone. But it lit up no problem and ran smoothly. I was FREAKING OUT for no reason.

2) The gas generation is easily controlled by the dimmer.

3) for the test run I was just bubbling it through water for a few minutes... well, disconnecting it I noticed two scents, one was of acetic acid the other was of something burning. The apparatus works, which is awesome. Not so awesome is that the black rubber laboratory stopper was starting to crack and there's sort of a brownish-black tar area on the claisen adapter just below the stopper that built up as the ketene lamp ran.

For reasons of safety, I might never pursue this. It was unnerving, but the method sure does work.

</two cents>


improving the bowel movements of cats & dogs everywhere...
 
 
 
 
    foxy2
(Distinctive Doe)
04-12-02 09:32
No 295935
      fire risk  Bookmark   

So how much fire/explosion risk is there?
Is that why hypo has not been posting lately?shocked

Or is it because the synth worked so well and he's too high?smile


Those who give up essential liberties for temporary safety deserve neither liberty nor safety
 
 
 
 
    LaBTop
(Daddy)
04-12-02 23:49
No 296159
      Umm,  Bookmark   

Hypo, please insert a safety device in front of that burning flame.
Simple, make a glasstube completely filled with very fine RED copper turnings or wire, this will directly extinguish any sucked back flame! This could happen when you have a pressure drop inside. LT/

WISDOMwillWIN
 
 
 
 
    hypo
(Hive Bee)
04-13-02 11:05
No 296379
      nice!  Bookmark   

acetyl:

very cool! - i like the fact that 36swg seems to work too (which is considerably thinner than the 0.5mm (about 24swg) used by my experimenter). more choice is allways good. some endurance test would be very interesting. i'll try and push my experimenter to get 2 multimeters. also i'd really like to know how current, length of wire and strength of wire relate to the amount of ketene produced. is there any easy way to measure that?

i figure that this was a proof of concept - if you want to pursue your way to AA, don't forget to add an acetone trap, i think no standard lab condenser is able to condense all of the acetone out of the hot ketene / ch4 mixture. also seal the rubber stopper with a good deal of PTFE tape _and_ use good ventillation.

the thing with the stopper is strange - the grey rubber stopper you see in the picture some posts above did not suffer at all even after 5 hours of operation. the plastic connectors on the outside melted and the bottom of the stopper got brown, but this was more linked to the agressive atmosphere than to heat. maybe because the Cu wires are longer or better a removing heat? or the quality of the grey stopper is simply better?

the smell - i think you simply smelled the ketene. the AA will smell that way too. (the experimenter is distilling the AA through the same condensor he uses to condense the acetone vapours, maybe he shouldnt do that...)

foxy:

there seems to be no great danger once all air is replaced by acetone vapors inside the lamp. and you know how easy it is to reflux acetone - 5 minutes on oil bath and you can start. also overheating seems to be no problem. once the experimenter accidentially turned the knob of the variac to the far right and the wire simply disintegrated, but otherwise nothing happened.

labtop:

i promise that the next time there will be a U shape drying tube (the only one available) with copper turnings between flame and apparatus. suckback never happened once, because fast bubbling seems like the way to go. only the current going off could be a problem. wouldn't a washing bottle filled with water do the trick too?