Acid- and base-catalyzed hydrolysis of chloroacetamide herbicides.
Despite the prevalence of chloroacetamides as herbicides, little is known about the rates or products of acid- or base-catalyzed hydrolysis of these compounds. Mechanisms of acid-catalyzed reactions may parallel those catalyzed by (hydr)oxide minerals, while base-catalyzed processes have as important counterparts reactions with environmental nucleophiles (such as reduced sulfur species). The current study systematically investigates how the structure of nine chloroacetamides affects their reactivity in 2 N NaOH, 2 N HCl, or 6 N HCl at 25 or 85 degrees C. Base-catalyzed hydrolysis proceeds either through an intermolecular SN2 reaction to hydroxy-substituted derivatives or (in a few cases) through amide cleavage, while both amide and ether group cleavages are observed under acidic conditions. Our results reveal that subtle differences in chloroacetamide structure [notably the type of (alkoxy)alkyl substituent] can dramatically influence reactivity and reaction mechanism. Hydroxy-substituted, morpholinone, and secondary aniline derivatives were identified upon reaction for several years in deionized water at circumneutral pH.
Carlson
Daniel L
DL
Department of Geography and Environmental Engineering, Johns Hopkins University, 313 Ames Hall, 3400 North Charles Street, Baltimore, Maryland 21218-2686, USA.
Than
Khoi D
KD
Roberts
A Lynn
AL
D000081:Acetamides / Q000737:chemistry*; D006540:Herbicides / Q000737:chemistry*; D006851:Hydrochloric Acid / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D012972:Sodium Hydroxide / Q000737:chemistry; D012996:Solutions
D000081:Acetamides; D006540:Herbicides; D012996:Solutions; C013874:chloroacetamide; D012972:Sodium Hydroxide; D006851:Hydrochloric Acid