NMR study of hydrothermal reactions of dichloromethane with and without alkali

Hydrothermal reactions of considerably concentrated (ca. 1 M; M = mol dm(-3 )) dichloromethane, CH2Cl2, were investigated with and without alkali in th e temperature range of 150-300 degreesC by using batch reactors, such as an autoclave and sealed glass tubes. H-1, H-2, and C-13 NMR spectra were take n at room temperature as a function of reaction time to analyze the quenche d reactants, intermediates, and products. In the presence of NaOH at 2 M, t he complete dechlorination was achieved in 270 min at 250 degreesC and in 6 0 min at 300 degreesC. Such gaseous by-products as CO, CO2, and H-2 were ge nerated by the decomposition of the disproportionation product, HCOO-. With out alkali. CH2(OH)2 could be detected by H-1 and C-13 NMR as an intermedia te in the hydrolysis of CH2Cl2, before such Cannizzaro products as methanol and formate ion were formed. The mechanism of the hydrothermal reactions o f CH2Cl2 is discussed in terms of the hydrolysis intermediate, CH2(OH)(2).