The reactions of H and D atoms with thin films of formaldehyde and methanol at cryogenic temperatures

The reactions of H and D atoms with solid formaldehyde (H2CO) and methanol (CH3OH) were investigated in the temperature region of 10 - 30 K. From the reaction of H with solid H2CO at 10 K, CO, CH3OH, and paraformaldehyde (polyoxymethylene) were the major products, with yields of about 1% or less under the experimental conditions. The yields of these products decrease steeply with an increase in temperature, and they become negligible at similar to 25 K. From the reaction of D with solid H2CO at 10 K, CO, HDCO, CH2DOD, and paraformaldehyde were formed. The branching ratio of the reaction [D + HCO --> CO + HD] to [D + HCO --> HDCO] was measured to be about 1: 6. The ratio of the yield of CH3OH from the reaction [H + H2CO] to that of CH2DOD from the reaction [D + H2CO] is similar to 7: 1; i.e., there is a marked isotope effect on the addition reaction of H and D to H2CO. In the reaction of H and D with CH3OH, H2CO was not detected as a reaction product.