2-[(4-tert-butyl-2,6-dimethylphenyl)methyl]-4,5-dihydro-1H-imidazole;hydron;chloride

Usesanthelmintic

UsesXylometazoline hydrochloride may be used as a reference standard in determining the xylometazoline hydrochloride content in samples of nasal drops using high performance liquid chromatography (HPLC).

UsesXylometazoline hydrochloride is used as a nasal decongestant.

General DescriptionXylometazoline hydrochloride is a derivative of imidazole, and a representative of the class of α1 agonists. It is commonly used in nasal decongestants, which works on the principle of constricting the blood vessels in the mucous membranes.

PreparationStarting with 1,3-dimethyl-5-tert-butylbenzene, it reacts with a chloromethylating agent in the presence of a catalyst to give 2,6-dimethyl-4-tert-butyl-1-chloromethylbenzene; cyanidation with sodium cyanide yields 2,6-dimethyl-4-tert-butyl-1-phenylacetonitrile, which is then cyclized with ethylenediamine p-toluenesulfonate to give xylometazoline p-toluenesulfonate (11); xylometazoline is then freed with alkali and reacted with hydrogen chloride to form a salt to give xylometazoline hydrochloride. The drawbacks of this process route are: tert-butyl-m-xylene has a high market price; chloromethyl ether is highly toxic, has a low boiling point, and a high market price; and highly toxic solvents such as carbon disulfide have low boiling points, resulting in poor reaction operability. Another synthetic route involves reacting 2,6-dimethyl-4-tert-butylaniline hydrochloride as a starting material with sodium nitrite, copper sulfate, and paraformaldehyde to generate 2,6-dimethyl-4-tert-butylbenzaldehyde. This is then reduced to an alcohol, followed by chloromethylation, hydrogenation, amino esterification, cyclization, and salt formation to produce xylometazoline hydrochloride. This synthetic route is lengthy and involves complex post-processing. Analysis shows that the diazotization reaction in this method generally has low yields; the use of thionyl chloride causes significant environmental pollution; it is difficult to scale up production; and the resulting product contains many impurities and has low purity. In summary, this synthetic method has a long process route, cumbersome post-processing, low product yield, and high production costs, making it difficult to achieve large-scale industrial production.