| Abstrakt: |
Clay‐organic complexes of urea‐d4, methylurea‐d3, and I,I‐dimethylurea‐d2with montmorillonite were examined by infrared spectroscopy in an effort to add to our understanding of the mechanism of adsorption of the substituted urea herbicides in soils. The complexes were examined in the infrared as dried thin self‐supporting films. Deteration techniques were used to correlate infrared spectra with molecular structure. Urea‐d4was found to be adsorbed in the interlayer space by montmorillonite through coordination of the carbonyl with the exchange cations. The degree of coordination with the exchangeable cation was least for Ca, intermediate for Ni (II), and largest for Al, representing alkaline earth cation‐clay, transition metal cation‐clay, and acid clay, respectively. Methylurea‐d3and I,1‐dimethylurea‐d2reacted with montmorillonite through the carbonyl in a manner similar to urea. The reaction of dimethylurea with montmorillonite was limited by the presence of the methyl groups to the extent that its reaction was the same with Al or Ni as the exchange cation. The amino groups of urea, methylurea, and I,I‐dimethylurea appear relatively inactive as bonding sites. |
