KINETIC-STUDIES ON THE FORMATION OF N-NITROSO COMPOUNDS .11. NITROSATION OF DIMETHYLAMINE BY NITRITE ESTERS IN AQUEOUS BASIC-MEDIA

A kinetic study of the mechanism of the nitrosation of dimethylamine (DMA) by propyl nitrite (PrONO) in basic media to yield N-nitrosodimethylamine (NDMA) has found the rate equation to be {Mathematical expression} where [DMA] and [PrONO] are total concentrations. At 298.2 K and I=0.25 M, k2=(6.59±0.13)·10-2M-1 s-1 and K1=(1.16±0.07)·10-11M. The observed influence of ionic strength, the kinetic results obtained in water/tetrahydrofuran mixtures and in heavy water (kH/kD=2.09), and the value of ΔS# (-158 JK-1 mol-1) suggest that the nitrosating agent PrONO attacks the free amine to create a tetracentric transition state and that this is the rate controlling step of the reaction. Experiments carried out with other nitrite esters have shown there to be a correlation satisfying Taft's equation between their structure and their reactivity with DMA (ρ*=3.89), which allows the rate constant for nitrous acid to be calculated. © 1986 Springer-Verlag.