Pitfalls in the Application of Hückel’s Rule

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 3 Issue 2 (1998), S1430-4171(98)02190-6

Pitfalls in the Application of Hückel’s Rule

Richard Francis Langler

Department of Chemistry, Mount Allison University, Sackville, New Brunswick E4L 1G8
Canada

Published online: 2 April 1998

Abstract. A semicircular mnemonic is described which permits one to anticipate the Hückel eigenvalue patterns for symmetrical contiguous nonfused bicycles (e.g., biphenyl). The mnemonic constitutes a new technique that is complementary to the existing Frost circle mnemonic for hydrocarbon monocycles. Pedagogically, the development of this semicircular mnemonic in class will serve to establish that the widespread practice of applying Hückel’s rule to polycycles is unsound.

Key Words: In the Classroom; Frost circle mnemonic; aromatic bicycles; biphenyl; semicircular mnemonic; Dewar resonance energies

(*) Corresponding author. (E-mail: rlangler@mta.ca)

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