Syreformen har en [[halveringstid]] på 140 minnutter i 37&nbsp;°C i [[vand]], hvor baseformen ([[anion]]en har en halvveringstid på 130 timer. Den reagerer altså omkring 55 gange langsommere.<ref>{{cite journal |doi= 10.1071/CH9671823 |author1=Hay, R. W. |author2=Bond, M. A. |year= 1967|title= Kinetics of decarboxilation of acetoacetic acid|url= https://archive.org/details/sim_australian-journal-of-chemistry_1967-09_20_9/page/1823 |journal= Aust. J. Chem.|volume = 20|issue=9|pages=1823–8}}</ref>
It is a [[weak acid]] (like most alkyl carboxylic acids), with a [[acid dissociation constant|pK<sub>a</sub>]] of 3.58.
Kemi