Behavior of the --single Reactor option has been fixed/improved [forum topic].
Removed --use-cache, --allow-duplicates, and --remove-duplicate-refs options from Reactor CLI.
Reactor started enhanced stereo group numbering from 2 [bug report]
Product standardization was removed from Reactor application,
react command line application, and Reactor Java API
Please visit this page for History of changes relating older JChem versions.