Aminoacetone hydrochloride

A mixture of concentrated hydrochloric acid (175 ml) and water (175 ml) is added to the acetamidoacetone (52 g, 0.45 mol). The mixture is boiled under reflux in a nitrogen atmosphere (6h) and concentrated by flash evaporation below 60°C using a condensation trap for solvent cooled in a dry-ice-acetonc bath. A dark, oily residue (40-45 g) is obtained. This is very hygroscopic but can be dried over P2O5 in a vacuum desiccator. Purification is achieved by recrystallization from absolute ethanol, adding ether until cloudy. This reagent can be stored as the semicarbazone, from which aminoacetone can be generated as required in siru. 

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Senucarbazide hydrochloride, conversion to semicarbazone, 46, 2 reaction with aminoacetone hydrochloride, 46, 2... 

Aminoacetone hydrochloride is very hygroscopic and is best stored as the semicarbazone. If the compound itself is desired, however, the dark red oil is dried under reduced pressure over phosphorus pentoxide. The resulting crystalline aminoacetone hydrochloride can be purified by dissolving it in absolute ethanol and precipitating it by the addition of dry ether. 

This preparation is based on the procedure used to synthesize 3-acetamido-2-butanone. Aminoacetone hydrochloride has been... 

B. Aminoacetone hydrochloride. A mixture of 175 ml. of concentrated hydrochloric acid and 175 ml. of water is added to 52 g. (0.45 mole) of the acetamidoacetone from step A contained in a 1-1. round-bottomed flask. The mixture is boiled under reflux under a nitrogen atmosphere (Note 4) for 6 hours. The resulting solution is concentrated using a flash evaporator held below 60° and with the condensation trap for solvent being... 

Alkylpyrazines are prepared by two main procedures, (1) self-condensation of a-amino carbonyl compounds and (2) alkylation (or acylation) of pyrazines at nuclear or side chain carbons. Condensation of aminoacetone hydrochloride (491) in the presence of the corresponding aldehyde gave the 3- -alkyl-2,5-dimethylpyrazines 20e and 20g (Scheme 61) 36). 2,5-Dimethylpyrazine 20a was prepared from hydroxyiminoacetone (493) by reduction with tin and hydrochloric acid (Scheme 61) 145). 3-Ethyl-2,6-dimethylpyrazine (21b) was prepared along with 20a and 495 by condensation of aminoacetone hydrochloride (491) with 2-aminopentan-3-one hydrochloride (494) in the presence of sodium ethoxide (Scheme 61) 36). 

Wilen has shown by PMR measurements that 2,5-dihydro-3,6-dimethylpyrazine (169) is the major product from the reaction of a-aminoacetone hydrochloride with potassium hydroxide in the absence of air. PMR measurements also indicate the presence of minor amounts of either the isomeric 1,4-dihydro (170) or 1,2-dihydro derivative (171). Compound 169 is slowly converted on standing at room temperature into a dimer, C12H20N4, the structure of which is still being investigated.376 The self-condensation of two molecules of... 

In addition to the preparations listed in Table II.1, Gabriel and Colman (187) have obtained, from the reaction of aminoacetone hydrochloride with potassium hydroxide, a liquid base (188, 189) that has now been assigned the structure 2,5 -dimethyl-3,6-dihydropyrazine (190). 

Aq. semicarbazide hydrochloride added to a soln. of aminoacetone hydrochloride in alcohol, and allowed to stand 2 hrs. at room temp. aminoacetone semicarbazone hydrochloride. Y 72-78%. J. D. Hepworth, Org. Synth. 45, 1... 

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