Radiation chemistry of acetals. Part 1. Photolysis (λ 185 nm) of formaldehyde dimethyl acetal in the liquid phase

Abstract

In the photolysis (λ 185 nm) of liquid formaldehyde dimethyl acetal the following products are formed (quantum yields in parentheses) : hydrogen (0.04), methane (0.22), ethane (0.01), formaldehyde (>0.15), methanol (0.35), methyl formate (0.17₅), dimethyl ether (0.13), methyl ethyl ether (0.02₅), acetaldehyde dimethyl acetal (0.04), formaldehyde methyl ethyl acetal (0.04), 1,2-dimethoxyethane (0.025), methoxyacetaldehyde dimethyl acetal (0.07₄), formaldehyde methoxyethyl methyl acetal (0.05₄), and dehydro-dimers (0.1). It is concluded that the photolysis is largely governed by reactions (i)–(v). Reaction (i) and (iv) include cage disproportionation processes. H₂C(OCH₃)₂ [graphic omitted] HCOOCH₃+ CH₄ϕ= 0.18 (i), H₂C(OCH₃)₂ [graphic omitted] CH₃OCH₂O˙+˙CH₃ϕ= 0.17 (ii), H₂C(OCH₃)₂ [graphic omitted] CH₃OCH₂˙+˙OCH₃ϕ= 0.18 (iii), H₂C(OCH₃)₂ [graphic omitted] CH₂O + CH₃OCH₃ϕ= 0.13 (iv), H₂C(OCH₃)₂ [graphic omitted] H˙+˙CH₂OCH₂OCH₃+ HĊ(OCH₃)₂ϕ= 0.04 (v)