Über die saure und alkalische Desaminierung der γ-Aminovaleriansäure

Abstract

When treated at pH 3 to 4 with an aqueous solution of sodium nitrite and sodium chloride γ-aminovaleric acid is transformed into γ-valerolactone, Δ⁴-pentenoic acid and trans-Δ³-pentenoic acid. Neither products containing chlorine nor cis-Δ³-pentenoic acid have been found. As stated elsewhere γ-valerolactone is produced predominantly with retention of configuration, but the direct participation of the carboxyl group during lacton formation is only 35%; this was demonstrated by deamination of ¹⁸O-labelled substrate. The reaction is thought to be groundstate-controlled : the intermediate diazonium ion is built up and breaks down in the conformation A, the open carbonium ion B reacts with the carboxyl group and its coordinated water molecules. This mecanism is confirmed by the results obtained when deamination by means of p-diazobenzenesulfonic acid is run at about pH 8, for the same products are formed in equal amounts.
In strongly alcaline solution (pH > 12) the same products are still formed, but the product-controlling step is the breakdown of the N-alkyl-bond of the 1,5-diaryl-3-alkylpentazadiene intermediate C in a conformation analogous to B.