Radioactive methanol

C-methyl iodide co-reaction with non-radioactive methanol... 

The active site concentration on the organochromium catalysts may be higher than that of the oxide catalysts. The activity usually assumes a more linear increase with chromium loading than on the oxide catalysts, at least up to 2% Cr. Yermakov and Zakharov, studying allyl-Cr(III)/silica catalysts, stopped the polymerization with radioactive methanol, and found that the kill mechanism is different from that on the oxide catalysts (59). The proton of the methanol, and not the alkoxide, became attached to the polymer. This suggests a polarity opposite to that of the oxide catalysts, with the site being more positive than the chain. 

Thus, at least a considerable fraction of the CO2 was derived by a direct reaction pathway involving radioactive methanol. 

Mixtures of CO + H2 and CO2 + H2 were reacted with one component, either CO or CO2, containing C label.Table 6 shows that on a mixed oxide catalyst, hardly any label appeared in the methanol end product from 00, but the use of C02 resulted in radioactive methanol. A side reaction of CO and water diluted considerably the radioactivity of the CO2 fraction after reaction. Reaction (8) was found valid on iron catalysts. Related studies (mainly those carried out in Moscow) have been summarised by Rozovskii.I ... 

Some radioactive methanol-acetic acid solutions from gel electrophoresis can be recycled via distillation and the methanol reused. The solution is neutralized prior to distillation to protect the distillation equipment from corrosion and to reduce the level of methyl acetate formed during the process. 

The slightly different physical properties of deuterium allow its concentration in ordinary hydrogen (or the concentration of a deuterium-containing compound in a hydrogen compound) to be determined. Exchange of deuterium and hydrogen occurs and can be used to elucidate the mechanism of reactions (i.e. the deuterium is a non-radioactive tracer). Methanol exchanges with deuterium oxide thus ... 

Synthetic chemical approaches to the preparation of carbon-14 labeled materials iavolve a number of basic building blocks prepared from barium [ CJ-carbonate (2). These are carbon [ C]-dioxide [ CJ-acetjlene [U— C]-ben2ene, where U = uniformly labeled [1- and 2- C]-sodium acetate, [ C]-methyl iodide, [ C]-methanol, sodium [ C]-cyanide, and [ CJ-urea. Many compHcated radiotracers are synthesized from these materials. Some examples are [l- C]-8,ll,14-eicosatrienoic acid [3435-80-1] inoxn. [ CJ-carbon dioxide, [ting-U— C]-phenyhsothiocyanate [77590-93-3] ftom [ " CJ-acetjlene, [7- " C]-norepinephrine [18155-53-8] from [l- " C]-acetic acid, [4- " C]-cholesterol [1976-77-8] from [ " CJ-methyl iodide, [l- " C]-glucose [4005-41-8] from sodium [ " C]-cyanide, and [2- " C]-uracil [626-07-3] [27017-27-2] from [ " C]-urea. All syntheses of the basic radioactive building blocks have been described (4). 

Table IV presents the results of the determination of polyethylene radioactivity after the decomposition of the active bonds in one-component catalysts by methanol, labeled in different positions. In the case of TiCU (169) and the catalyst Cr -CjHsU/SiCU (8, 140) in the initial state the insertion of tritium of the alcohol hydroxyl group into the polymer corresponds to the expected polarization of the metal-carbon bond determined by the difference in electronegativity of these elements. The decomposition of active bonds in this case seems to follow the scheme (25) (see Section V). But in the case of the chromium oxide catalyst and the catalyst obtained by hydrogen reduction of the supported chromium ir-allyl complexes (ir-allyl ligands being removed from the active center) (140) C14 of the...

Waszczuk P, Wieckowski A, Zelenay P, Gottesfeld S, Coutanceau C, Leger JM, Lamy C. 2001b. Adsorption of CO poison on fuel ceU nanoparticle electrodes from methanol solutions A radioactive labeling study. J Electroanal Chem 511 55-64. 

Coutanceau C, Hahn F, Waszczuk P, Wieckowski A, Lamy C, Leger J-M. 2002. Radioactive labeling study and FTIR measurements of methanol adsorption and oxidation on fuel cell catalysts. Fuel Cells 2 153-158. 

In subsequent smdies, it was shown that, atfer hydrolysis, about 42% of the total radioactive residue in grain may be identified as 4-fert-butylcyclohexanone. Moreover, 34-90% of the TRR was extracted by heating the plant material under reflux with a mixture of methanol and hydrochloric acid. The performance of that method was properly demonstrated by individual fortification experiments with the parent compound and the three primary metabolites (bold in Figure 1). 

Radioactive 11C-methyl labeling for study of methanol co-reaction with methyl iodide on Fe -Beta zeolite... 

The adsorption of methanol as well as methyl iodide was complete at ambient temperature on Fe-Beta-300 (917 m2/g surface area) since radioactive gas was not detected at catalyst outlet. Only a small part of methyl iodide (conversion rate was 10-25 %) while most part of methanol was converted (conversion rate was 60-90 %) up to... 

Figure 1. Radio-signals of UC- products in nC-methanol conversion (a) at 300 °C and nC-methanol conversion with non-radioactive CH3I (b) at 350 °C.

C-methanol co-reaction with non-radioactive methyl iodide on Fe-Beta-300 The 11 C-methanol with non-radioactive methyl iodide was investigated to study the modification of the methanol reaction mechanism in co-reaction with methyl iodide. 

The radioactive signals of radio-GC show the 1 -methanol derivates and its common derivates with non radioactive methyl iodide (Fig. lb). The nC-methanol derivates take part in new molecule formation with non-radioactive methyl iodide or/and its derivates on catalyst surface. The C-methyl iodide as a newly formed radioactive product was detected while the selectivity to hydrocarbons sharply decreased (Fig. 2b). 

The radiochemical assays were done as follows At the end of a polymerisation experiment, when the conductivity had become constant, a ten-fold excess of tritiated water was added from a burette (see Figure 1), the cell was warmed rapidly to room temperature, and any polymer which had been precipitated during the polymerisation was allowed to re-dissolve. It was always noted that no hydrolysis occurred until the solutions reached 0 °C. This could be seen from a rapid drop of conductivity to a very low value. The solvent and most of the tritiated water were then distilled out, within about 15 minutes. The polymer was then dissolved in toluene, also run from a burette into the reaction vessel, which was then cut from the vacuum line. The polymer was precipitated in methanol and prepared for the determinations of radioactivity and DP. For the radiochemical assay the polymers were dissolved in toluene, re-precipitated in methanol, dried, weighed, re-dissolved in toluene, and the activity determined. The processes of precipitation and dissolution were repeated until the activity of the polymer became constant, (up to 7 repetitions). It was assumed that when the activity had become constant, all the excess of tritium had been removed. 

Of the total radioactivity in fish, ether extracted 78.26, petroleum ether 10.79, and methanol 10.95%. Percent composition of each of these fractions is shown in vertical column. 

About 84% of the radioactivity in the excreta was extracted with methanol, another 9% was extracted with a 1% hydrochloric acid/ methanol mixture leaving about 7% unextracted. It was found by TLC that 75% of the methanol-soluble radioactivity was due to the presence of unchanged robenidine (Figure 3). Metabolites 1, 2, and 3 accounted for 7, 2 and 0.7% of the extractable radioactivity, respectively. 

The nature of the radioactivity in the water, soil and fish from the carbon-14 DDT experiment was examined by thin-layer chromatography as shown in Figure 5. The radioactivity in the water was very polar in nature and did not migrate appreciably from the origin. About 78% of the radioactivity in the soil was extracted with methanol. The major metabolite in the extractable fraction was DDD which represented 33% of the total radioactivity. The reductive dechlorination of DDT to DDD is a known pathway under anaerobic conditions and has been shown to be due to microbial metabolism (5). Since carbon-14 DDT was incor-... 

In the fish, the last element in the food chain web, methanol extracted about 58% of the radioactivity resulting from the carbon-14 robenidine treatment leaving 42% unextracted, indicating that robenidine was being extensively degraded by fish into very polar nonextractable products. 

Figure 8. TLC of the methanol-soluble radioactivity in the fish from the UC-robenidine model ecosystem...

---