Acetamidine hydrochloride is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

with the formula , used in the synthesis of many nitrogen-bearing compounds. It is the

hydrochloride In chemistry, a hydrochloride is an acid salt resulting, or regarded as resulting, from the reaction of hydrochloric acid with an organic base (e.g. an amine). An alternative name is chlorhydrate, which comes from French. An archaic alternati ...

of acetamidine, one of the simplest

amidine Amidines are organic compounds with the functional group RC(NR)NR2, where the R groups can be the same or different. They are the imine derivatives of amides (RC(O)NR2). The simplest amidine is formamidine, HC(=NH)NH2. Examples of amidines includ ...

Properties

Acetamidine hydrochloride is a

hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption (chemistry), absorption or adsorption from the surrounding Natural environment, environment, which is usually at normal or room temperature. If water mol ...

solid which forms colourless monoclinic crystals. It is soluble in water and alcohol. It releases

ammonium chloride Ammonium chloride is an inorganic chemical compound with the chemical formula , also written as . It is an ammonium salt of hydrogen chloride. It consists of ammonium cations and chloride anions . It is a white crystalline salt (chemistry), sal ...

upon heating. Dry acetamidine hydrochloride releases

acetonitrile Acetonitrile, often abbreviated MeCN (methyl cyanide), is the chemical compound with the formula and structure . This colourless liquid is the simplest organic nitrile (hydrogen cyanide is a simpler nitrile, but the cyanide anion is not class ...

, while in aqueous solution, it instead undergoes

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main compone ...

and

ammonia Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...

. :
: As free base amidines are strong

Lewis base A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...

s, acetamidine hydrochloride is a weak

Lewis acid A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any ...

. Treatment with strong base gives free base acetamidine: :

Synthesis

Acetamidine hydrochloride is synthesised in a two-step process that begins with a solution of

ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...

at close to . First, the mixture is treated with anhydrous

hydrogen chloride The Chemical compound, compound hydrogen chloride has the chemical formula and as such is a hydrogen halide. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric water vapor. Hyd ...

in a

Pinner reaction The Pinner reaction refers to the acid catalysed reaction of a nitrile with an alcohol to form an imino ester salt (alkyl imidate salt); this is sometimes referred to as a Pinner salt. The reaction is named after Adolf Pinner, who first described ...

, producing crystals of acetimido ethyl ether hydrochloride: : The imino ether salt is then treated with an excess of

in dry ethanol, converting the ether to the

: : All reagents must be thoroughly dried using a strong desiccant such as

phosphorus pentoxide Phosphorus pentoxide is a chemical compound with molecular formula Phosphorus, P4Oxygen, O10 (with its common name derived from its empirical formula, P2O5). This white crystalline solid is the anhydride of phosphoric acid. It is a powerful desic ...

, as the intermediate imido ether is susceptible to

, yielding

and

ethyl formate Ethyl formate is an ester formed when ethanol (an alcohol) reacts with formic acid (a carboxylic acid). Ethyl formate has the characteristic smell of rum and is partially responsible for the flavor of raspberries, occurring naturally in some plan ...

. Layers of ammonium chloride can form on the imido ether salt, limiting the formation of amidine.

Applications

As a source of

, acetamidine hydrochloride is a precursor to the industrial and laboratory synthesis of many nitrogen compounds. It reacts with β-

dicarbonyl In organic chemistry, a dicarbonyl is a molecule containing two carbonyl () groups. Although this term could refer to any organic compound containing two carbonyl groups, it is used more specifically to describe molecules in which both carbonyls ...

s to produce substituted

pyrimidine Pyrimidine (; ) is an aromatic, heterocyclic, organic compound similar to pyridine (). One of the three diazines (six-membered heterocyclics with two nitrogen atoms in the ring), it has nitrogen atoms at positions 1 and 3 in the ring. The oth ...

s, with

acetaldehyde Acetaldehyde (IUPAC systematic name ethanal) is an organic compound, organic chemical compound with the chemical formula, formula , sometimes abbreviated as . It is a colorless liquid or gas, boiling near room temperature. It is one of the most ...

s to form substituted

imidazole Imidazole (ImH) is an organic compound with the formula . It is a white or colourless solid that is soluble in water, producing a mildly alkaline solution. It can be classified as a heterocycle, specifically as a diazole. Many natural products, ...

s, and with

imidate Carboximidates (or more general imidates) are organic compounds, which can be thought of as esters formed between an imidic acid () and an Alcohol (chemistry), alcohol, with the general formula . They are also known as imino ethers, since they ...

s to form substituted

triazine Triazines are a class of nitrogen-containing heterocycles. The parent molecules' molecular formula is . They exist in three isomeric forms, 1,3,5-triazines being common. Structure The triazines have planar six-membered benzene-like ring but ...

s. In particular, its reaction with a dicarbonyl intermediate is an early step in the synthesis of thyamine (vitamin B₁) and many of its derivatives.

References

{{Reflist Hydrochlorides Amidines