Acetamidine hydrochloride

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Acetamidine hydrochloride
IUPAC name
Ethanimidamide hydrochloride
Preferred IUPAC name
Ethanimidamide hydrochloride
Other names
Acetimidamide hydrochloride
Acetamidinium chloride
Acetamidine HCl
Ethanimidamide monohydrochloride
Ethanimidamidium hydrochloride
Molar mass 94.54 g/mol
Appearance White solid
Odor Odorless
Melting point 165–170 °C (329–338 °F; 438–443 K)
Boiling point Decomposes
11 g/100 ml (20 °C)[1]
Solubility Soluble in ethanol, methanol
Insoluble in acetone, chloroform, diethyl ether, ethyl acetate, toluene
Safety data sheet Sigma-Aldrich
Related compounds
Related compounds
Guanidinium chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Acetamidine hydrochloride is an organic chemical compound with the formula CH3C(=NH)NH2·HCl. It is the hydrochloride salt of acetamidine (acetimidamide).



Acetamidine hydrochloride will react with strong bases to yield freebase acetamidine.

Hydrolysis of the compound yields ammonium chloride and acetic acid, which occurs upon heating. If no water is present, acetamidine will decompose to acetonitrile and ammonium chloride.[2]

Heating acetamidine hydrochloride with acetic anhydride at 185 °C yields 2, 4-dimethyl-6-acetylaminopyrimidin.[3]

Acetamidine can react with malononitrile in the presence of sodium ethoxide to form pyrimidines.[4]


Acetamidine hydrochloride is a hygroscopic colorless solid, soluble in water and alcohols.


Acetamidine hydrochloride is sold by chemical suppliers.


Acetamidine hydrochloride, like all amidines, can be prepared via the Pinner reaction. The preparation of acetamidine hydrochloride requires all reagents be very dry. Thus both acid and base desiccating agents are necessary.

In a reaction flask, solution comprised of anhydrous acetonitrile and absolute ethanol are added, and a suitable anti-suckback gas bubbling system is employed. The reaction flask is cooled using crushed ice and salt. Anhydrous hydrogen chloride gas is introduced in the system for several hours while stirring the solution. The dry HCl gas reacts with the cooled acetonitrile/ethanol to produce 1-ethoxyethanimine hydrochloride, which precipitates out of the solution. If the resulting imine HCl solidifies, it may be ground up in a mortar under absolute ethanol, before being returned in the flask.

A solution of anhydrous ammonia in anhydrous ethanol is prepared and its concentration is determined. The alcoholic solution of ammonia is titrated to determined the concentration of ammonia from the solution.

The ethanol-ammonia solution is slowly added to the imine HCl under stirring, which causes the imine to gradually dissolve and react with the ammonia. As the reaction advances, ammonium chloride precipitates out of the solution. Once all the NH4Cl has precipitated out of the solution, the suspension is filtered and the filtrate is carefully recrystallized by slowly heating it to drive off the ethanol. On cooling, the acetamidine hydrochloride separates in long colorless prisms. These are filtered by suction, washed with a little cold ethanol, and dried in a desiccator over conc. sulfuric acid.[5]


  • Preparation of various imidazoles, pyrimidines, triazines
  • Synthesis of FOX-7



There is little toxicological information for acetamidine hydrochloride, though the compound does not require special protection when handling.


In closed airtight bottles, preferably in a desiccator.


Should be strongly diluted and poured down the drain.

Alternatively, it can be neutralized with a strong oxidizing solution, under controlled conditions.


  1. Armarego W. L. F. Purification of Laboratory Chemicals. - 7ed. - 2013. - pp. 104
  2. R. L. Shriner and Fred W. Neumann, The Chemistry of the Amidines, 1944

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