Photooxidation of Dimethyl Methylphosphonate on TiO₂ Powder

Abstract

The photooxidation of dimethyl methylphosphonate (DMMP) on powdered TiO 2 has been studied using UV irradiation in the range 2.1 eV to 5.0 eV. It has been found that the P-CH 3 and the P-OCH 3 moieties are destroyed together by photooxidation, producing adsorbed CO and CO 2 as well as formate ions and water. By working at 200 K the photooxidation process has been studied alone, whereas at room temperature both hydrolysis and photooxidation will occur together. An adsorbed PO 3 species is the final phosphorus-containing photooxidation product. High coverages of DMMP are not photooxidized due to site blockage for O 2 adsorption on the TiO 2 surface.

Fourier Transform Microwave Spectrum and ab Initio Study of Dimethyl Methylphosphonate

“…Although there were transitions in the general vicinity of all of the predicted a-type lines, they could not be fit together with the b-and c-types. Figure 5 shows a high-resolution scan near 13.5 GHz where the 4 14 -3 13 and the 4 04 -3 03 a-type pair is predicted. The two arrows at the bottom show the exact location of the two transitions as predicted from the b-and c-type fit.…”

Adsorption and Decomposition of CWA Simulants on Single Crystal and Nanostructured Metal Oxides

“…The only precedence for complete oxidation of DMMP by molecular oxygen at room temperature on TiO 2 involves the use of UV radiation to produce conductionband electrons, which activate the oxygen. [3][4][5] In this study, we observe the production of similar products, but in the dark and at room temperature.…”

“…The broad band at ~ 1560 cm -1 suggests the formation of formate or carboxylate on Au-TiO 2 . [2][3][4][5] In addition, bands around 2100 cm -1 show that the Au-TiO 2 is active enough to form surface-bound carbon monoxide, a clear indication of the DMMP oxidation. 3 In contrast, no CO bands have ever been detected on pure-TiO 2 following DMMP exposure in the absence of UV radiation.…”

“…[2][3][4][5] In addition, bands around 2100 cm -1 show that the Au-TiO 2 is active enough to form surface-bound carbon monoxide, a clear indication of the DMMP oxidation. 3 In contrast, no CO bands have ever been detected on pure-TiO 2 following DMMP exposure in the absence of UV radiation. The high reactivity of the Au-TiO 2 is likely due to a combination of factors, 6 including the presence of highly reactive surface oxygen.…”

Hybrid Organic-Inorganic Materials Based on Organophosphorus Derivatives

“…Most probably, coordination of the phosphoryl oxygen to the surface assists the condensation by increasing the electrophilicity of the P atom, thus facilitating the condensation of P-O-R groups with surface hydroxyls (Scheme 7) [124]. The chemisorption of gaseous phosphonate or phosphate esters on metal oxide surfaces has been extensively studied for the detection and the decontamination of pesticides and chemical warfare agents [182][183][184]. It is noteworthy that in the case of diethylphosphonate coupling molecules, the dissolution-precipitation mechanism discussed above was not observed for TiO 2 and Al 2 O 3 supports, even under severe conditions.…”