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Author: Subject: Unsuccessful Aminoguanidine Bicarbonate synthesis
LardmanAttack
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[*] posted on 11-4-2020 at 15:31
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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[*] posted on 11-4-2020 at 18:19


Have you read Engagers posts on this synthesis?
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LardmanAttack
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[*] posted on 11-4-2020 at 21:01


Quote: Originally posted by B(a)P  
Have you read Engagers posts on this synthesis?

Yes I have, many times.
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JohnDoe13
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[*] posted on 11-4-2020 at 21:04


Let me get my crystal ball...
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B(a)P
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[*] posted on 12-4-2020 at 01:30


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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[*] posted on 12-4-2020 at 02:57


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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[*] posted on 23-4-2020 at 01:39


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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[*] posted on 23-4-2020 at 01:43


I'm just mainly trying to figure out what problems other people have had and how they've overcome them.
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