R. Wrobel et al., Reactions of dimethyl ether with atomic oxygen: A matrix isolation and a quantum chemical study, J PHYS CH A, 103(19), 1999, pp. 3693-3705
The reaction of dimethyl ether (1) with atomic oxygen generated by photolys
is of ozone or N2O was examined in low-temperature matrices. The major reac
tion products are two conformers of methoxymethanol (5). IR absorptions of
the products were assigned by isotopic labeling (O-18 and D) and DFT calcul
ations at the B3LYP/ 6-311++G(d,p) level of theory. The mechanism of the fo
rmation of 5, in particular H abstraction from 1 by atomic oxygen ((OP)-P-3
and (OD)-D-1), was investigated using UMP, UCCSD(T), and UDFT. In both the
H abstraction and the O(D-1) insertion reaction, the out-of-plane C-H bond
s of 1 are preferentially attacked since the inplane C-H bonds are about 10
kcal/mol stronger. In the case of a reaction with O(P-3), an Arrhenius act
ivation energy of 3.5 kcal/mol is calculated at 298 K, which compares well
with an experimental value of 2.85 kcal/mol. In the exit channel of the rea
ction, a radical-radical complex between CH3CH2. and . OH (-2.7 kcal/mol re
lative to separated products) is found. The latter is the starting point fo
r the formation of 5 and helps to rationalize the stereoselectivity of the
reaction leading to particular conformations of 5.