pyridiniumn.
/ˌpɪrᵻˈdɪnɪəm/, U.S. /ˌpɪrəˈdɪniəm/ Chemistry.
A cation having the formula C5H6N+, consisting of a protonated pyridine molecule. Usually attributive or as a formative element in chemical names.
ΚΠ
1896 Jrnl. Amer. Chem. Soc. 18 32 It is easier to form a primary amine or ammonium salt of a tertiary alkyl than it is to form a pyridinium salt of the same alkyl.
1954 T. Vickerstaff Physical Chem. Dyeing (ed. 2) iii. 84 Polar Yellow R may form stable micelles similar in structure to those of cetyl pyridinium bromide.
1977 J. March Adv. Org. Chem. (ed. 2) ii. 43 Derivatives such as N-oxides or pyridinium ions are still aromatic.
1997 Economist 4 Jan. 80/2 Though fat-like in the blood and thus easily ushered through the endothelium, they are transformed by enzymes on the other side into water-soluble compounds known as pyridinium salts.
This is a new entry (OED Third Edition, December 2007; most recently modified version published online March 2022).
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