selenious acid synthesis

Hydrogen selenide and telluride are stronger reducing agents than the sulfides, with the reducing power increasing in the order H2S, H2Se, H2Te, in line with the decreasing thermal stability of the hydrides. The reaction of phosphorus pseudohalogens with tricoordinate phosphorus compounds offers an alternative route to symmetrical monoselenopyrophosphates (47,48). This extremely exothermic reaction must be conducted at −100 to −95 °C under anhydrous conditions. Mono- and di-selenium compounds (196–197) are synthesized by reaction of selenous acid and the corresponding sulfur derivatives (Scheme 86) 〈75KGS275, 76KGS1361〉. In the tellurium series the bis(2,4-dinitrophenylhydrazone) of 1,3-cyclopentadione and tellurium dioxide give only 2% of (208). Reacts exothermically with many reducing agents including hydroiodic acid, sulfurous acid, sodium hyposulfite, hydroxylamine salts, hydrazine salts, hypophosphorous acid, phosphorous acid [Merck]. Linear Formula H 2 SeO 3. 6-Chloro or 6-methoxy derivatives of the compounds (195–197) afford the corresponding 6-amino derivatives by a nucleophilic displacement reaction using anilines, dimethylamine and piperidine (Scheme 85) 〈77KGS1499〉. 6.7.6). Further purification was achieved by column chromatography on silica gel, eluting with benzene and chloroform, or by recrystallisation from 1:1 v/v benzene–light petroleum. Thus, the diaminopyrimidines (191) produce the [1,2,5]selenadiazolo[3,4-d]pyrimidine derivatives (192) (50–65%) (Equation (29)) 〈08CB3957, 58JOC1940, 67JHC96〉. Compound (200a) is thermally stable and is unreactive towards bromine and concentrated sulfuric acid at room temperature. It had been shown that the toxicity of Se is largely due to changes that occur in the tertiary structure of proteins in cases where Se substitutes for S. However, oxidative stress [12, 13] and reactive oxygen species (ROS) may also be factors in Se toxicity [14, 15] associated with carcinogenesis, cytotoxicity, and genotoxicity [16, 17]. Selene(IV) as selenious acid is precipitated by hydrogen sulfide in 0.4 M hydrochloric acid. The mass spectral data for compounds (198) and (199) are compared with their sulfur analogs and the spectral data show the high degree of stability of the three analogs studied. Selenium is a nonmetal element with the atomic number 34 and the chemical symbol Se. Selenium pE-pH diagram at 25°C, 1 bar pressure and zero ionic strength for dissolved Se activity of 10–10 mol/L. Selenium dioxide and tellurium dioxide react with 1,3-diketone dioximes unsubstituted at position 2, to give compounds (198) and (199), respectively. In both these systems selenium is introduced into the ring using an aqueous solution of selenous acid. Selective reaction of dialkyl trimethylsilyl phosphites with O,O-dialkyl O-trimethylsilyl phosphoroselenonates and sulfuryl chloride provides tetra-alkyl monoselenopyrophosphates (58a–f) in excellent yields (Fig. By continuing you agree to the use of cookies. Alternative procedures use copper sulfate and phosphoric acid instead. Philip Knowles, in Comprehensive Heterocyclic Chemistry II, 1996. As a crystalline solid, the compound can be seen as pyramidal molecules that are interconnected with hydrogen bonds. Interestingly, bis(dialkylphosphoryl) diselenides (76) and (79) are obtained from an analogous reaction of the salts of O,O-dialkyl hydrogen phosphoroselenoates with bis(dialkylphosphoryl) disulfides (5). Selenous acid 98% Synonym: Selenious acid CAS Number 7783-00-8. Grey, metallic selenium is the only crystalline3,57,58 and the ordinary commercial form of the element. [7], Selenious acid is a key component of the Mecke reagent used for drug checking. This process deposits a coating of copper selenide and is fundamentally different from other bluing processes which generate black iron oxide. The major use is in protecting and changing the color of steel, especially steel parts on firearms. in laboratory preparation of glyoxal (ethane-1,2-dione) from acetaldehyde. The semiconducting elements of Group VI, selenium and tellurium, form the hydrides hydrogen selenide, H2Se, and hydrogen telluride, H2Te. Selenic acid, H2SeO4, has been obtained by the oxidation of selenous acid with strong oxidizing agents. Selenium monochloride and tellurium tetrachloride give identical results (Scheme 88) 〈49JCS274, 79BSF(2)199〉. Similar reactions involving nitrene or carbene insertions have been used to prepare other type A systems. Serves as an oxidizing agent. CRC Handbook of Chemistry and Physics. We use cookies to help provide and enhance our service and tailor content and ads.

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