On a very regular basis I receive requests now from ChemSpider users for what I would call “General Help”. Here’s a request from a user to answer a Chemistry Question. Can the community help?

“We have detected 2,2 Dichloropropionic Acid  in several of our drinking water systems at levels of about 0.1 to 0.2 ug/L (above the EU MCL), but none in the source water (in some cases surface water, in others, groundwater under the direct influence of surface water).  The levels in the pipe rise after the addition of free chlorine.  This leads me to believe that either some sort of lab interference or some other compound is actually being detected.  We have sent samples to two separate labs using two different methods (blanks were not sent) and the results were confirmed.

Any thoughts on how 2,2 Dichloropropionic Acid might be naturally formed in the presence of chlorine in drinking water? Is it possible that other organics either degrade down to 2,2 Dichloropropionic Acid or are precursors for 2,2 Dichloropropionic Acid, in the presence of chlorine?”

Please post your comments on this blog and I will ask the user to watch this page.

This is part of our future endeavors. Shortly we will establish a discussion forum for ChemSpider users so that when a user has scientific problems you can post here and discuss. Should the outcome from the discussion be science associated with a particular chemical we will add it to a record n the database for further reference.

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3 Responses to “A Request for Assistance from a ChemSpider User”

  1. Rich Apodaca says:

    Although I don’t have access to the journal, you might want to check out this paper:


    Analysis of haloacetic acid mixtures by HPLC using an electrochemical detector coated with a surfactant-nafion film

    It discusses methods for the analysis of haloacetic acids. They probably spell out why they’re interested in this class of analytes (alpha-halo carboxylic acids) in the introduction. Might be a start.

  2. Rich Apodaca says:

    BTW, the analyte could be accounted for by electrophillic alpha-chlorination of proprionic acid in a process analogous to the first steps of the haloform reaction:


    I’d check for proprionic acid in the water.

  3. Ann Richard says:

    I forwarded the inquiry to a fellow EPA scientist, Susan Richardson, who I consider the foremost expert on occurrence data relative to disinfection by-products in US finished (tap) water. Susan is an analytical chemist and has published some of the most thorough and definitive review papers on the subject. With her permission to post, her response is as follows:

    Yes, 2,2-dichloropropanoic acid is a DBP. We see it all the time in chlorinated water. You can also get it in chloraminated water. So, it’s not your imagination or an artifact/contamination issue–it is a legitimate DBP that we see all the time. (We also see 3,3-dichloropropenoic acid all the time, too, as well as many other 3-carbon, 4-carbon, and 5-carbon mono-acids and di-acids, and a few tri-acids). These are widely ignored because they aren’t regulated or on any lists for concern here in the U.S.

    Just for fun, I’m pasting in a list of haloacids (mono and diacids) that have been found as chlorine DBPs (the ones underlined have been confirmed with standards and have been found in real drinking waters, as opposed to lab chlorinations of source waters). I’m currently working on an updated encyclopedia article on DBPs, and these are fresh on my mind!

    2-Chloropropanoic acid, 2,2-Dichloropropanoic acid, 2,2-Dibromopropanoic acid, 3,3,3-Trichloropropanoic acid, Isomer of 3,3,3-Trichloropropanoic acid, 2,2-Dichloro-3-hydroxypropanoic acid, Trichloropropanoic acid (2 isomers), 3,3,3-Trichloro-2-hydroxypropanoic acid, 3,3,3-Trichloro-2-hydroxy-2-methylpropanoic acid, 2-Chlorobutanoic acid, 2-Chloro-4-hydroxybutanoic acid, 2,2-Dichlorobutanoic acid, Isomer of 2,2-dichlorobutanoic acid, 2,4-Dichloro-3-hydroxybutanoic acid, Trichlorooxobutanoic acid, 4,4,4-Trichloro-3-hydoxybutanoic acid, 3,3,5,5,5-Pentachloro-4-hydroxybutanoic acid, 2-Chloro-3-methylbutanoic acid, 2-Chloropentanoic acid, 3-Chloro-4-oxopentanoic acid, 2,2-Dichloropentanoic acid, Dichloropentanoic acid (3 isomers), 3,3-Dichloro-4-oxopentanoic acid, 2,5-Dichloro-2-methylpentanoic acid, Trichloropentanoic acid, Tetrachlorohydroxypentanoic acid, 3,3,5,5,5-Pentachloro-4-hydroxypentanoic acid, 2,3,3,5,5,5-Hexachloro-4-hydroxypentanoic acid, 5,5,5-Trichloro-4-oxopentanoic acid, 2-Chlorohexanoic acid, 2,2-Dichlorohexanoic acid, Isomer of 2,2-Dichlorohexanoic acid, 6,6-Dichlorohexanoic acid, Tetrachlorohydroxyoxohexanoic acid (2 isomers), Tetrachlorooxohexanoic acid, Pentachlorooxohexanoic acid, 2-Chloroheptanoic acid

    2,2-Dichloropropenoic acid, 3,3-Dichloropropenoic acid, (cis) and (trans)-2,3-Dichloropropenoic acid, 3,3-Dichloropropenoic acid, cis and trans-Bromochloropropenoic acid, 3,3-Dibromopropenoic acid, Trichloropropenoic acid, 2-Bromo-3,3-dichloropropenoic acid, (E) and (Z)-3-Bromo-2,3-dichloropropenoic acid, Chlorobutenoic acid (2 isomers), Trichloro-4-oxo-methylbutenoic acid, 3-Chloro-2-methyl-4-hydroxy-2-butenoic acid, 2,3-Dichlorobutenoic acid, Trichlorobutenoic acid, Tetrachlorobutenoic acid, 4-Chloro-5-hydroxy-3-pentenoic acid, 2,3-Dichloro-4-oxopentenoic acid, Trichloro-4-oxo-pentenoic acid (2 isomers), 2-Chloro-3-(dichloromethyl)-4-oxopentenoic acid, Isomer of 2-Chloro-3-(dichloromethyl)-4-oxopentenoic acid, 2,5,5,5-Tetrachloro-4-oxopentenoic acid, 3,5,5,5-Tetrachloro-4-oxo-2-methylpentenoic acid, Isomer of 3,5,5,5-Tetrachloro-4-oxo-2-methylpentenoic acid, Pentachlorooxopentenoic acid, 2,5,5-Trichloro-4-oxopentenoic acid, 3,5,5-Trichloro-4-oxopentenoic acid, 2,3,5,5-Tetrachloro-4-oxopentenoic acid, 2,5,5,5-Tetrachloro-4-oxopentenoic acid, 3,5,5,5-Tetrachloro-4-oxopentenoic acid, Pentachloropentenoic acid, Tetrachlorooxohexenoic acid, Heptachloro-5-oxo-hexenoic acid

    2,2-Dichloropropanedioic acid, Chlorobutanedioic acid (2 isomers), 2,2-Dichlorobutanedioic acid, 2,3-Dichlorobutanedioic acid, Trichlorobutanedioic acid, 2-Chloro-3-(trichloroacetyl)butenedioic acid, cis-2-Chlorobutenedioic acid (chloromaleic acid), trans-2-Chlorobutenedioic acid (chlorofumaric acid), cis and trans-2-Bromobutenedioic acid, cis-2,3-Dichlorobutenedioic acid (dichloromaleic acid), trans-2,3-Dichlorobutenedioic acid (dichlorofumaric acid), trans-2,3-Dibromobutenedioic acid, cis and trans-2-Chloro-3-methylbutendioic acid, cis-2-Bromo-3-methylbutenedioic acid, 3-Chloro-2-(dichloromethyl)-butenedioic acid, 2,2-Dichloropentanedioic acid, Isomer of 2,2-Dichloropentanedioic acid, Tetrachlorohydroxypentanedioic acid, Dichloromethyl isomer of tetrachlorohydroxypentanedioic acid, Trichlorohydroxypentanedioic acid, Chloropentenedioic acid (2 isomers), Dichloropentenedioic acid, Trichloropentenedioic acid, Tetrachloropentenedioic acid, 2-Carboxy-3,5,5,5-Tetrachloro-4-oxopentenoic acid, Chlorohexanedioic acid, 2,2-Dichlorohexanedioic acid, Tetrachlorohexanedioic acid, 2-Chloroheptanedioic acid, 2-Chlorooctanedioic acid, 2,2-Dichlorooctanedioic acid, Dichlorooctenedioic acid, 2-Chlorononanedioic acid

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