Oktober 28, 2026Pyridine hydrochloride – CAS# 628-13-7 – Preparation and Application
General description
Pyridine hydrochloride or pyridinium chloride [628-13-7] is hydrochloric salt of pyridine. It is a colorless to yellow crystalline solid with the melting point of 144-146 °C.[1] It is soluble in water, chloroform, ethanol and insoluble in diethyl ether. Pyridine hydrochloride is very hygroscopic compound. It is harmful if swallowed and it causes skin, eye and respiratory irritation.[2]
Preparation
Pyridinium chloride can be easily produced by passing hydrogen chloride throught pyridine dissolved in diethyl ether until precipitation is complete.[3]
Application of Pyridine hydrochloride
Pyridine hydrochloride has been extensively used for ether cleavages, cyclization and dehydration reactions. Methyl aryl ethers are deprotected in high yields using pyridine hydrochloride in the absence of solvent under microwave irradiation.[4] As a reagent for cyclodehydration it is especially useful if concominant demethylation is required[5] or where the hydroxy group involved in cyclization is formed by demethylation.[6] It was used in dehydration of some triterpenoid epoxides into unrearranged dienes.[7] It has served as a crucial reagent in final step of the synthesis of Resistomycin that involves desilylative aromatization, demethylation and cyclization.[8]
Product categorization (Chemical groups):
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[2] https://pubchem.ncbi.nlm.nih.gov/compound/Pyridinium-chloride#section=Safety-and-Hazards
[3] M. D. Taylor, L. R. Grant J. Chem. Educ. 1955, 32 (1), 39. doi:10.1021/ed032p39
[4] P. P. Kulkarni, A. J. Kadam, R. B. Mane, U. V. Desai, P. P. Wadgaonkar J. Chem. Res. (S) 1999, 394. doi:10.1039/A901278H
[5] E. G. Brain, F. Cassidy, M. F. Constantine, J. C. Hanson, D. J. D. Tidy J. Chem. Soc. C 1971, 3846. doi:10.1039/J39710003846
[6] N. P. Buu-Hoi, B. Ekert, R. Royer J. Org. Chem. 1954, 19 (9), 1548. doi:10.1021/jo01374a020
[7] I. Morelli, A. Marsili J. Org. Chem. 1970, 35 (3), 567. doi:10.1021/jo00828a006
[8] B. A. Keay, R. Rodrigo J. Am. Chem. Soc. 1982, 104 (17), 4725. doi:10.1021/ja00381a05