LardmanAttack
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Unsuccessful Aminoguanidine Bicarbonate synthesis
I've been trying to work my way up the ladder of syntheses to get to tetrazole compounds and I'm currently on the synthesis of aminoguanidine
bicarbonate. Unfortunately, I've tried it twice so far with only a negligible amount of product both times (>10g when I should've gotten 30+)
I'm curious as to what the main thing i'm doing wrong is, I tried my best to get good PH and temperature control, And I assumed I was doing decent
with it but apparently not.
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B(a)P
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Have you read Engagers posts on this synthesis?
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LardmanAttack
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Yes I have, many times.
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JohnDoe13
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Let me get my crystal ball...
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B(a)P
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I have tried that reaction 3 times and never done better than about 20% yield. I have since found a reliable source of LR aminoguanadine bicarbonate
so I never worked out where I was going wrong.
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Boffis
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LardmanA; If you want us (SM) to help you we will need you to supply a lot more detail about the exact method you used, your observations as you went
along, the source and quality of reagents used, the accuracy of your weighing equipment, scale of operation etc. As JohnDoe13 says its a little tricky
without a crystal ball to know what might have gone wrong. I have prepared this compound many times and yields vary greatly between batches.
If I start from crude commercial 50-55% Calcium Cyanamide I am usually happy with 20% yield, thats about normal though it can be as high as 35% based
on cyanamide content. If I am using the thiourea route 60-65% is more typical but this route is very smelly and only suitable for people living in
isolated places.
Also there is the care you took when follow even well written procedures such as those of Engager, lack of care = poor yields; the Devil is in the
detail!
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LardmanAttack
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Quote: Originally posted by Boffis  | LardmanA; If you want us (SM) to help you we will need you to supply a lot more detail about the exact method you used, your observations as you went
along, the source and quality of reagents used, the accuracy of your weighing equipment, scale of operation etc. As JohnDoe13 says its a little tricky
without a crystal ball to know what might have gone wrong. I have prepared this compound many times and yields vary greatly between batches.
If I start from crude commercial 50-55% Calcium Cyanamide I am usually happy with 20% yield, thats about normal though it can be as high as 35% based
on cyanamide content. If I am using the thiourea route 60-65% is more typical but this route is very smelly and only suitable for people living in
isolated places.
Also there is the care you took when follow even well written procedures such as those of Engager, lack of care = poor yields; the Devil is in the
detail! |
I am following Engager's synthesis directly (56g hydrazine sulfate and 40g cyanamide) so as to make as little mistakes as possible, My calcium
cyanamide was made from urea and calcium oxide and calcinated in a fire, I know for a fact it isn't the best quality, but i've seen people do the same
and get much, much better yields. And the hydrazine was from urea and bleach. The PH was a little bit acidic throughout the additions but not
excessively so, I believe that my hydrazine had sulfuric acid contamination so next time I try the synthesis, i'll recrystallize it first. i'll also
likely attempt to make better cyanamide as it was a little oxidized.
[Edited on 23-4-2020 by LardmanAttack]
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LardmanAttack
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I'm just mainly trying to figure out what problems other people have had and how they've overcome them.
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