Hydrolysis and dehalogenation of trihaloacetaldehydes

The aqueous stability of three brominated trihaloacetaldehydes (THAs), bromodichloroacetaldehyde, chlorodibromoacetaldehyde, and tribromoacetaldehyde, was studied. All three brominated THAs were found to undergo rapid hydrolysis at high pHs fanning trihalomethanes (THMs). The hydrolysis rate can be expressed as -d[THA]/dt = kott[THA][OH-]0.5. A rapid dehalogenation of these THAs was also found in the presence of sulfite over a range of pHs. The dehalogenation rate can be expressed as -[THA)/dt = k1[THA] [HS03 -1 + k2[THA][SOl-J. These results indicate that THAs are unstable in alkaline drinking waters. The authors also recommend that high pH and sulfite quenching should be avoided during THA analysis.