Abstract
We measured the absolute rate constants for the hydrogen peroxide oxidation of two different octyl dimethyl amines in isopropanol/water mixtures at 23°C. The amines were 1-octyl dimethyl amine (1) and 2-ethylhexyl dimethyl amine (2); their structures were analogous to those most often encountered in commercial alkyl dimethyl amine oxide production. The observed first-order rate constants for the disappearance of amine across a range of H2O2 concentrations (0.5–8 M) indicated that the overall rate was first-order in amine and 3/2-order in H2O2. Calculations showed k 1=0.16 M−1h−1, k 2=0.046 M−1h−1, and k 1/k 2=3.5. The rates appeared to decrease with increasing steric hindrance around the nitrogen atom. We also investigated the effect of water on the reaction rates. When [H2O]<∼4.5 M in isopropanol, the rates increased with increasing [H2O]; for [H2O]>∼4.5 M, the rates were insensitive to [H2O].
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Gee, J.C., Williamson, R.C. Kinetics of hydrogen peroxide oxidation of alkyl dimethyl amines. J Amer Oil Chem Soc 74, 65–67 (1997). https://doi.org/10.1007/s11746-997-0121-1
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DOI: https://doi.org/10.1007/s11746-997-0121-1