Halo ketones and halo carbonyl compounds in general are synthesized by reaction of carbonyl compounds with sources of X (X = halogen), which is provided using halogens:
:RC(O)CH  +  X  →  RC(O)CHX  +  HX
Specialized sources of electrophilic halogenating agents include N-Bromosuccinimide and 1,3-dibromo-5,5-dimethylhydantoin (DBDMH). In the Nierenstein reaction an acyl chloride reacts with diazomethane