Sciencemadness Discussion Board

Guanidine from dicyanodiamide

Bezaleel - 7-1-2020 at 12:19

Being quite inexperienced in organic syntheses, I wonder whether (how?) guanidine can be made from dicyanodiamide (2-cyanoguanidine).

I have the attached procedure for making biguanidine from dicyanodiamide, but I'm also interested in making guanidine or its salts from it.

Does anyone know of a route for synthesis of it?

Attachment: biguanide.pdf (99kB)
This file has been downloaded 330 times

Boffis - 11-1-2020 at 03:15

@Bezaleel; I have done a lot of work with dicyandiamide and have dozens of papers on its transformation into other compounds. It is certainly possible to produce guanidine. Basically when dicyandiamide is fused with an ammonium salt biguanide is a transient product on route to guanidine. Biguanide concentrations reach a max fairly quickly and at low temperatures (optimum if I recall correctly is about 120-130) as heating is prolonged and the temperature increased towards 160-180 C the proportion of guanidine and other products increases. If there is an excess of ammonium salt the eventual product is guanidine of whatever anion was in the ammonium salt. Ammonium iodide and nitrate produce the best yields of biguanide while higher melting point salts give mostly quanidine. If you can give me a few days I dig out some of the papers.

wg48temp9 - 11-1-2020 at 04:54

Quote: Originally posted by Boffis  
@Bezaleel; I have done a lot of work with dicyandiamide and have dozens of papers on its transformation into other compounds. It is certainly possible to produce guanidine. Basically when dicyandiamide is fused with an ammonium salt biguanide is a transient product on route to guanidine. Biguanide concentrations reach a max fairly quickly and at low temperatures (optimum if I recall correctly is about 120-130) as heating is prolonged and the temperature increased towards 160-180 C the proportion of guanidine and other products increases. If there is an excess of ammonium salt the eventual product is guanidine of whatever anion was in the ammonium salt. Ammonium iodide and nitrate produce the best yields of biguanide while higher melting point salts give mostly quanidine. If you can give me a few days I dig out some of the papers.


I would appreciate you posting the papers also.
Thanks in advance.

Boffis - 12-1-2020 at 03:30

Attached is a zip file that contains some papers on the conversion of dicyandiamide into guanidine. There are 4 papers but I have more info somewhere though it may be in books such as Inorganic Syntheses or Brauer etc. I'll check some more.

Incidentally last summer I did a lot of experiments at producing dicyandiamide from fertilizer grade calcium cyanamide. These were successful even if the yield by weight is a bit low. (The commercial material is only about 50% calcium cyanamide but is very cheap so this isn't really an issue)

Attachment: Guanidine from dicyandiamide.zip (982kB)
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wg48temp9 - 12-1-2020 at 06:56

Quote: Originally posted by Boffis  
Attached is a zip file that contains some papers on the conversion of dicyandiamide into guanidine. There are 4 papers but I have more info somewhere though it may be in books such as Inorganic Syntheses or Brauer etc. I'll check some more.

Incidentally last summer I did a lot of experiments at producing dicyandiamide from fertilizer grade calcium cyanamide. These were successful even if the yield by weight is a bit low. (The commercial material is only about 50% calcium cyanamide but is very cheap so this isn't really an issue)


Thanks Boffis

S.C. Wack - 12-1-2020 at 07:51

Hot sulfuric acid.

wg48temp9 - 15-1-2020 at 23:20

I found an interesting old paper titled "COMPLEX COMPOUNDS OF BIGUANIDES AND CUANYLUREAS WITH METALLIC ELEMENTS".

It also discusses the synthesis biguanides and their reactions.

It has the synthesis of an unusually coloured copper complex, here is a short snip about it "The composition of the copper(I1) bis(biguanide)
complexes can be represented by the general formulas [CU(Bg)2] and[CU(BgH)2]X2, where BgH = a molecule of biguanide or substituted biguanide and X =OH or any univalent anion or an equivalent of any polyvalent anion. They all form red, rose-red, or redviolet crystals."

Attachment: ray1961.pdf (4.9MB)
This file has been downloaded 491 times