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National Hazard
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Ketene lamp with blow torches instead of resistive wire
Folks,
I'd like to know if anyone tried to pyrolyse acetone in a piece of quartz tube put in the flame of a Bunsen burner/blow torch rather than using an
electric wire. The idea is to vaporise acetone, feed it into the tube then collect ketene on the other side.
Of course, this is somewhat less efficient than a true ketene lamp which can collect unreacted acetone and feed it back. But as a first approach, it
could make sense.
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Parakeet
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I don't see why not. Early researchers used quartz tube heated in an elctric furnace. | Quote: |
A flow system was employed in which pure dry nitrogen saturated with the vapor of the acetone or higher ketone was passed at a known rate through a
quartz tube heated in an electric furnace.
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However, ketene tends to decompose at high temperature. Precise temperature controle seems to be important, which explains why electric heating is
preferred than burner.
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National Hazard
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Quote: Originally posted by Parakeet  | | I don't see why not. However, ketene tends to decompose at high temperature. Precise temperature controle seems to be important, which explains why
electric heating is preferred than burner. |
Aha. So, too low, no ketene, too high, carbon. Ok. This will be a game of trial and error… Thanks!
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leau
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That's going to be more risky but hopefully you'll survive to tell us about it 
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National Hazard
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I’m going to do it outside!
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Fulmen
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Good idea, that way you'll get some sun and fresh air while poisoning and blowing yourself up 
We're not banging rocks together here. We know how to put a man back together.
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Organikum
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Ketene also likes to polymerize to form diketene, so even with perfect temperature control you will not end up with a tube full of ketene. Question is
why? What do you want your ketene for? An interesting concept was in one articel which presented the heating wire submerged into acetone in a well
cooled flask, the wire then sits in a self-created bubble of gas and the formed gases are cooled instantly when bubbling through acetone, a condenser
then de-mists those gases and ketene was said to be made in a very compact and simple setup the distance to the next step where ketene reacts with
something is kept very short too, it makes a lot of sense to implement it this way.
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National Hazard
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| Quote: Originally posted by Organikum | | Ketene also likes to polymerize to form diketene, so even with perfect temperature control you will not end up with a tube full of ketene. Question is
why? What do you want your ketene for? |
Try to get some Ac₂O I suppose? But is more a proof of concept than anything else. Ac₂O is workable using S₂Cl₂ and sodium acetate in a much
safer way. Just like a challenge, like making oleum.
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clearly_not_atara
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If you want to be clever about it, why not that variation using a solar concentrator (Fresnel lens / mirrors)? Seems like you could calibrate the
whole setup to get the right temperature long before actually starting the gas flow.
Diketene is more interesting than ketene anyway; there are loads of ways to make Ac2O, but diketene makes all kinds of weird products.
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