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thebean
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Hey magpie, can I substitute the heating mantle with anything?
"You need a little bit of insanity to do great things."
-Henry Rollins
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Mailinmypocket
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@thebean
Unintentionalchaos used a regular ceramic top hotplate as seen. An aluminum foil skirt around the flask will help to capture the rising heat from the
plate as well.
Very interesting btw, I need to order me some niacin 
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gdflp
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Does anyone know if ammonium dichromate is required for the preparation of the catalyst? Could sodium or potassium dichromate be substituted because
they tend to be much cheaper?
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Loptr
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Preparation of high-active copper chromite dehydrogenation catalyst
A solution of 260 g of Copper(II)nitrate trihydrate in 900 ccm of tap water at 80°C was added while stirring to a soln 178 g of sodium dichromate
dihydrate and 225 ml of 28% NH4OH made up to 900 ml at 25°C. The precipitate was collected by suction filtration and slurried in water three times.
The copper ammonium chromate was dried at 75-80C overnight. This was powdered and added in small portions to a one liter 3-neck flask equipped with a
stainless steel stirrer Hershberg type which scrapped close to the bottom of the flask. The flask was partially immersed in a Woods-alloy metal bath
at 350°C (with 300-320°C, one can obtain good results). The time of addition was 15 min (a lot of fumes evolved) and the mixture was stirred at
350°C for another 15 min after all was complete. The cooled and black dusty powder used as is for the dehydrogenation.
Reference: JACS 71, 1130 (1949)
https://www.erowid.org/archive/rhodium/chemistry/copperchrom...
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CuReUS
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why is the pyridine not turning dark due to the exposure to light
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Amos
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I think that takes a good deal of time.
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careysub
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Is the catalyst reusable for multiple preparations? I would guess yes, but has this been tested?
This method of obtaining pyridine is really neat.
It avoids shipping a hazardous substance, which is also a watched chemical, and is MUCH cheaper than buying prepared pyridine.
Currently buying 98 g of pyridine from Elemental is $70 (reagent plus hazmat packaging), or about 70 cents per gram. Using inexpensive, readily
available niacin this costs 7 cents per gram.
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Amos
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When the copper sulfate and ammonium chromate + ammonia solutions are combined, is the precipitate formed copper chromate(CuCrO4), or copper ammonium
chromate(Cu(NH4)2(CrO4)2)? If it's the latter, could ordinary copper(II) chromate be decomposed in the same manner?
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UnintentionalChaos
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Quote: Originally posted by No Tears Only Dreams Now  | | When the copper sulfate and ammonium chromate + ammonia solutions are combined, is the precipitate formed copper chromate(CuCrO4), or copper ammonium
chromate(Cu(NH4)2(CrO4)2)? If it's the latter, could ordinary copper(II) chromate be decomposed in the same manner? |
The precipitate is a complex copper ammonium chromate. The decomposition of the product is dependent on exothermic redox between the ammonium cation
and chromate, so plain cupric chromate would not be effective.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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Amos
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| Quote: Originally posted by UnintentionalChaos | | Quote: Originally posted by No Tears Only Dreams Now | | When the copper sulfate and ammonium chromate + ammonia solutions are combined, is the precipitate formed copper chromate(CuCrO4), or copper ammonium
chromate(Cu(NH4)2(CrO4)2)? If it's the latter, could ordinary copper(II) chromate be decomposed in the same manner? |
The precipitate is a complex copper ammonium chromate. The decomposition of the product is dependent on exothermic redox between the ammonium cation
and chromate, so plain cupric chromate would not be effective. |
From wikipedia: Copper chromite is produced by thermal decomposition of one of three substances. The traditional method is by the uncatalyzed ignition
of copper chromate:
2CuCrO4 → 2CuCrO3 + O2
It has to work given some set of conditions, but perhaps not as readily or at a low temperature as with copper ammonium chromate.
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NZniceguy
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Could copper sulphate, pottassium dichromate and aqueous ammonia work also to make copper chromite catalyst? Or can anyone sell me a few grams of
catalyst?
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