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'Acetals' in keywords Facet   Publication Year 1991  [X]
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1Author    FerencD. UtkaRequires cookie*
 Title    Bioactive Chemical Bond Systems in Safeners and Prosafeners  
 Abstract    Acetals and ketals involving a dichloromethyl group on their central carbon atom were found to be active or highly active as safeners of corn against thiocarbamate and chloroacet-anilide herbicide injury. A mechanism for the biotransformation of these compounds as pro­ safeners to the actual dichloroacetic ester safeners is proposed. Similarly, S-and N-analogues of the cyclic acetals (ketals) which show safener activity can also be considered as prosafeners because they can be converted in the biophase by the same mechanism into actual safeners such as dichloroacetic thiolesters or dichloroacetamides sup­ porting the bioactivation hypothesis. Characteristic bioactive chemical bond systems in safeners and prosafeners are suggested. 
  Reference    Z. Naturforsch. 46c, 805 (1991); received March 26 1991 
  Published    1991 
  Keywords    Safeners, Prosafeners, Acetals, Ketals, MG-191 
  Similar Items    Find
 TEI-XML for    default:Reihe_C/46/ZNC-1991-46c-0805.pdf 
 Identifier    ZNC-1991-46c-0805 
 Volume    46 
2Author    Zsigmond Ekler, FerencD. UtkaRequires cookie*
 Title    Chemical Reactivity and Safener Activity of Acetal Compounds  
 Abstract    Although detailed examinations have been published on structure-activity relationships of herbicide safeners, only a few data are available on chemical reactivity-safener activity rela­ tionships. Chemical reactivity o f acetamide type compounds as well as their safener activity against thiocarbamate herbicides change with the number o f chlorine substituents in the order: non-chlorinated < monochloro < dichloro. Several compounds of another chemical group, acetals (e.g. MG-191, 2-dichloromethyl-2-methyl-l,3-dioxolane), are also effective safeners for thiocarbamate herbicides. According to our growth room studies, the safener activity o f ace­ tals also increases with increasing chlorine content up to two chlorine atoms on the same car­ bon. A number of differently chlorinated acetals have been synthesized and their acid-cata­ lyzed hydrolysis rate determined in order to establish a relationship between their bioactivity and chemical reactivity. The hydrolysis rate order of acetals containing no, one or two chlorine atoms: non-chlorinated > monochloro > dichloro, is just the opposite than what has been found for acetamides. Thus, safener activity of acetals increases with decreasing chemical reac­ tivity. The opposite reactivity order of acetamides and acetals can be explained by the different mechanisms of their hydrolysis. Dichloroacetals may not be effective safeners in their original structure. In plants, however, they can be biologically activated to active safeners by a trans­ formation other than hydrolysis. 
  Reference    Z. Naturforsch. 46c, 810—814 (1991); received March 26 1991 
  Published    1991 
  Keywords    Acetals, Hydrolysis, Herbicides, Herbicide Safeners, Zea mays (L) 
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 TEI-XML for    default:Reihe_C/46/ZNC-1991-46c-0810.pdf 
 Identifier    ZNC-1991-46c-0810 
 Volume    46