nonprotonic acid

chemical compound

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July 1, 2026

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A nonprotonic acid is a chemical compound that functions as an acid but does not contain hydrogen atoms that can be released as protons. This concept is part of the Lewis theory of acids and bases, which defines an acid as a species that can accept an electron pair from a base to form a chemical bond.1

Unlike traditional acids that donate protons (H+), nonprotonic acids, also known as Lewis acids, are characterized by their ability to accept electrons. Examples of nonprotonic acids include substances like sulfur trioxide (SO₃), aluminum chloride (AlCl₃), and boron trifluoride (BF₃). These compounds exhibit acidic properties such as neutralization of bases and catalysis, even without the presence of protons.231

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acid–base reaction
Alternative definitions
…the experimental fact that these nonprotonic acids often exhibit the properties regarded as typical of acids, such as neutralization of bases, action on indicators, and catalysis. Such substances often are electron acceptors, but this is not always the case; carbon dioxide (CO₂) and nitrogen pentoxide (N₂O₅), for example, contain completed…
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…the experimental fact that these nonprotonic acids often exhibit the properties regarded as typical of acids, such as neutralization of bases, action on indicators, and catalysis. Such substances often are electron acceptors, but this is not always the case; carbon dioxide (CO₂) and nitrogen pentoxide (N₂O₅), for example, contain completed…
Read More