23731-40-0Relevant articles and documents
Formation of complex organic molecules in methanol and methanol-carbon monoxide ices exposed to ionizing radiation - A combined FTIR and reflectron time-of-flight mass spectrometry study
Maity, Surajit,Kaiser, Ralf I.,Jones, Brant M.
, p. 3081 - 3114 (2015/02/05)
The radiation induced chemical processing of methanol and methanol-carbon monoxide ices at 5.5 K exposed to ionizing radiation in the form of energetic electrons and subsequent temperature programmed desorption is reported in this study. The endogenous formation of complex organic molecules was monitored online and in situ via infrared spectroscopy in the solid state and post irradiation with temperature programmed desorption (TPD) using highly sensitive reflectron time-of-flight (ReTOF) mass spectrometry coupled with single photoionization at 10.49 eV. Infrared spectroscopic analysis of the processed ice systems resulted in the identification of simple molecules including the hydroxymethyl radical (CH2OH), formyl radical (HCO), methane (CH4), formaldehyde (H2CO), carbon dioxide (CO2), ethylene glycol (HOCH2CH2OH), glycolaldehyde (HOCH2CHO), methyl formate (HCOOCH3), and ketene (H2CCO). In addition, ReTOF mass spectrometry of subliming molecules following temperature programmed desorption definitely identified several closed shell C/H/O bearing organics including ketene (H2CCO), acetaldehyde (CH3COH), ethanol (C2H5OH), dimethyl ether (CH3OCH3), glyoxal (HCOCOH), glycolaldehyde (HOCH2CHO), ethene-1,2-diol (HOCHCHOH), ethylene glycol (HOCH2CH2OH), methoxy methanol (CH3OCH2OH) and glycerol (CH2OHCHOHCH2OH) in the processed ice systems. Additionally, an abundant amount of molecules yet to be specifically identified were observed sublimating from the irradiated ices including isomers with the formula C3H(x=4,6,8)O, C4H(x=8,10)O, C3H(x=4,6,8)O2, C4H(x=6,8)O2, C3H(x=4,6)O3, C4H8O3, C4H(x=4,6,8)O4, C5H(x=6,8)O4 and C5H(x=6,8)O5. The last group of molecules containing four to five oxygen atoms observed sublimating from the processed ice samples include an astrobiologically important class of sugars relevant to RNA, phospholipids and energy storage. Experiments are currently being designed to elucidate their chemical structure. In addition, several reaction pathways were identified in the irradiated ices of mixed isotopes based upon the results of both in situ FTIR analysis and TPD ReTOF gas phase analysis. In general, the results of this study provide crucial information on the formation of a variety of classes of organics including alcohols, ketones, aldehydes, esters, ethers, and sugars within the bulk ices upon exposure to ionizing radiation that are relevant to the molecular clouds within the interstellar medium.
Ag/Au mixed sites promote oxidative coupling of methanol on the alloy surface
Xu, Bingjun,Siler, Cassandra G. F.,Madix, Robert J.,Friend, Cynthia M.
, p. 4646 - 4652 (2014/05/06)
Nanoporous gold, a dilute alloy of Ag in Au, activates molecular oxygen and promotes the oxygen-assisted catalytic coupling of methanol. Because this trace amount of Ag inherent to nanoporous gold has been proposed as the source of oxygen activation, a thin film Ag/Au alloy surface was studied as a model system for probing the origin of this reactivity. Thin alloy layers of Ag xAu1-x, with 0.15≤x≤0.40, were examined for dioxygen activation and methanol self-coupling. These alloy surfaces recombine atomic oxygen at different temperatures depending on the alloy composition. Total conversion of methanol to selective oxidation products, that is, formaldehyde and methyl formate, was achieved at low initial oxygen coverage and at low temperature. Reaction channels for methyl formate formation occurred on both Au and Au/Ag mixed sites with a ratio, as was predicted from the local 2-dimensional composition. Activation and promotion: Au/Au mixed sites promotes selective oxidation of methanol to formaldehyde and methyl formate without producing any CO2 (see scheme).
Broensted Basicity of Atomic Oxygen on the Au(110) Surface: Reactions with Methanol, Acetylene, Water, and Ethylene
Outka, Duane A.,Madix, R. J.
, p. 1708 - 1714 (2007/10/02)
The adsorption and reactions of methanol, acetylene, water, and ethylene were investigated on clean and oxidized Au(110) surfaces by temperature-programmed reaction spectroscopy.All of these molecules are only weakly and molecularly adsorbed on the clean Au(110) surface.Methanol, acetylene, and water, however, react with the oxidized surface.Methanol, activated by 0.25 monolayer of oxygen adatoms, reacts to form water, methyl formate, hydrogen, and carbon dioxide.A stable methoxy intermediate is identified in these reactions.Acetylene reacts to form water and carbon dioxide, and water is more strongly bonded to the Au(110) surface in the presence of oxygen adatoms.Ethylene is the only one of these molecules which does not react with oxygen adatoms on Au(110).This pattern of reactivity parallels that associated with the acidity of these molecules as measured in the gas phase which has been observed on Cu(110) and Ag(110) surfaces.These results complete the studies necessary to demonstrate the Broensted base character of oxygen adatoms on all of the group 1B metals.
