Details

Autor(en) / Beteiligte

• Perrin, Charles L.

Titel

Malonic Anhydrides, Challenges from a Simple Structure

Ist Teil von

• Journal of organic chemistry, 2022-06, Vol.87 (11), p.7006-7012

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2022

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• After many years of unsuccessful attempts, monomeric malonic anhydrides were prepared by ozonolysis of ketene dimers, a procedure validated by model studies. The structure proof relied most heavily on IR absorption at 1820 cm–1 and a Raman band at 1947 cm–1. Malonic anhydrides are unstable, decomposing below room temperature to a ketene plus carbon dioxide. Surprisingly, according to kinetic studies, the dimethyl derivative is slightly less unstable than the parent, and the monomethyl is the fastest to decompose, with an enthalpy of activation of only 12.6 kcal/mol. Computations rationalize this behavior in terms of a concerted [2s + 2a] cycloreversion that requires a more highly organized transition state, as also manifested by a negative entropy of activation.