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Dimethylphosphite
Dimethyl hydrogen phosphite (DMHP), also known as Dimethylphosphite, is an organophosphorus compound with the formula (CH3O)2P(O)H. It is a reagent for generating other organophosphorus compounds, exploiting the high reactivity of the P-H bond. The molecule is tetrahedral. It is a colorless liquid. The compounds can be prepared by methanolysis of phosphorus trichloride or by heating diethylphosphite in methanol. Due to the presence of hydrogen, a "soft" ligand, the compound resonates. DMHP exists in chemical equilibrium, in two structures. One of the structures has a lone electron cloud, which is nucleophilically attacking the remaining tetrahedral structure. Due to the structural equilibrium tending towards the phosphonate, this reaction is slow, needing a chemical or electromagnetic catalyst (heat). This tautomeric nature of DMHP made it desirable as a precursor to the G-series compounds, and it was the most successful among all other phosphonate precursors. The now obsolete ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diethylphosphite
Diethylphosphite is the organophosphorus compound with the formula (C2H5O)2P(O)H. It is a popular reagent for generating other organophosphorus compounds, exploiting the high reactivity of the P-H bond. Diethylphosphite is a colorless liquid. The molecule is tetrahedral. Synthesis and properties The compound was probably prepared in the 1850s by combining phosphorus trichloride and ethanol, but intentional preparations came later. It arises as follows: :PCl3 + 3 C2H5OH → (C2H5O)2P(O)H + 2 HCl + C2H5Cl Many derivatives can be prepared similarly. Despite being named as a phosphite it exists overwhelmingly in its phosphonate form, , a property it shares with its parent acid phosphorous acid; despite this many of its reactions are difficult to rationalise without assuming the existence of the following tautomerism equilibrium between phosphorus(V) and phosphorus(III) forms: :(C2H5O)2PV(O)H ⇌ (C2H5O)2PIII(OH) Reactions Alkoxide exchange Diethylphosphite undergoes transesterific ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organophosphorus Compound
Organophosphorus compounds are organic compounds containing phosphorus. They are used primarily in pest control as an alternative to chlorinated hydrocarbons that persist in the environment. Some organophosphorus compounds are highly effective insecticides, although some are extremely toxic to humans, including sarin and VX nerve agents. Organophosphorus chemistry is the corresponding science of the properties and reactivity of organophosphorus compounds. Phosphorus, like nitrogen, is in group 15 of the periodic table, and thus phosphorus compounds and nitrogen compounds have many similar properties. The definition of organophosphorus compounds is variable, which can lead to confusion. In industrial and environmental chemistry, an organophosphorus compound need contain only an organic substituent, but need not have a direct phosphorus-carbon (P-C) bond. Thus a large proportion of pesticides (e.g., malathion), are often included in this class of compounds. Phosphorus can adopt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrahedral Molecular Geometry
In a tetrahedral molecular geometry, a central atom is located at the center with four substituents that are located at the corners of a tetrahedron. The bond angles are cos−1(−) = 109.4712206...° ≈ 109.5° when all four substituents are the same, as in methane () as well as its heavier analogues. Methane and other perfectly symmetrical tetrahedral molecules belong to point group Td, but most tetrahedral molecules have lower symmetry. Tetrahedral molecules can be chiral. Tetrahedral bond angle The bond angle for a symmetric tetrahedral molecule such as CH4 may be calculated using the dot product of two vectors. As shown in the diagram, the molecule can be inscribed in a cube with the tetravalent atom (e.g. carbon) at the cube centre which is the origin of coordinates, O. The four monovalent atoms (e.g. hydrogens) are at four corners of the cube (A, B, C, D) chosen so that no two atoms are at adjacent corners linked by only one cube edge. If the edge length of the cube ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphorus Trichloride
Phosphorus trichloride is an inorganic compound with the chemical formula PCl3. A colorless liquid when pure, it is an important industrial chemical, being used for the manufacture of phosphites and other organophosphorus compounds. It is toxic and reacts readily with water to release hydrogen chloride. History Phosphorus trichloride was first prepared in 1808 by the French chemists Joseph Louis Gay-Lussac and Louis Jacques Thénard by heating calomel (Hg2Cl2) with phosphorus. Later during the same year, the English chemist Humphry Davy produced phosphorus trichloride by burning phosphorus in chlorine gas. Preparation World production exceeds one-third of a million tonnes. Phosphorus trichloride is prepared industrially by the reaction of chlorine with white phosphorus, using phosphorus trichloride as the solvent. In this continuous process PCl3 is removed as it is formed in order to avoid the formation of PCl5. :P4 + 6 Cl2 → 4 PCl3 Structure and spectroscopy It has a trig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleophile
In chemistry, a nucleophile is a chemical species that forms bonds by donating an electron pair. All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they are Lewis bases. ''Nucleophilic'' describes the affinity of a nucleophile to bond with positively charged atomic nuclei. Nucleophilicity, sometimes referred to as nucleophile strength, refers to a substance's nucleophilic character and is often used to compare the affinity of atoms. Neutral nucleophilic reactions with solvents such as alcohols and water are named solvolysis. Nucleophiles may take part in nucleophilic substitution, whereby a nucleophile becomes attracted to a full or partial positive charge, and nucleophilic addition. Nucleophilicity is closely related to basicity. History The terms ''nucleophile'' and ''electrophile'' were introduced by Christopher Kelk Ingold in 1933, replacing the terms ''anionoid'' and ''cationoid' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphonate
In organic chemistry, phosphonates or phosphonic acids are organophosphorus compounds containing groups (where R = alkyl, aryl, or just hydrogen). Phosphonic acids, typically handled as salts, are generally nonvolatile solids that are poorly soluble in organic solvents, but soluble in water and common alcohols. Many commercially important compounds are phosphonates, including glyphosate (the active molecule of the herbicide Roundup), and ethephon, a widely used plant growth regulator. Bisphosphonates are popular drugs for treatment of osteoporosis.Svara, J.; Weferling, N.; Hofmann, T. "Phosphorus Compounds, Organic," in ''Ullmann's Encyclopedia of Industrial Chemistry'', Wiley-VCH, Weinheim, 2008. . In biochemistry and medicinal chemistry, phosphonate groups are used as stable bioisoteres for phosphate, such as in the antiviral nucleotide analog, Tenofovir, one of the cornerstones of anti-HIV therapy. And there is an indication that phosphonate derivatives are "promising ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Otto Ambros
Otto Ambros (19 May 1901 – 23 July 1990) was a German chemist and Nazi war criminal. He is known for his wartime work on synthetic rubber (polybutadiene, or "Buna rubber") and nerve agents (sarin and tabun). After the war he was tried at Nuremberg and convicted of crimes against humanity for his use of slave labor from the Auschwitz III–Monowitz concentration camp. Early life The son of a university professor, Ambros attended school and passed his Abitur exam in Munich. In 1920 he went to the University of Munich to study chemistry and agricultural science. In 1925 he gained a doctorate, studying under the 1915 Nobel Prize for Chemistry winner, Richard Willstätter. Career Beginning in 1926, Ambros worked at BASF in Ludwigshafen. In 1930 he spent a year studying in the Far East. From 1934 he worked at IG Farben, becoming head of their Schkopau plant in 1935. His division of IG Farben developed chemical weapons, including the nerve agents sarin (in 1938) and soman (in 1944 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sarin
Sarin (NATO designation GB G-series, "B"">Nerve_agent#G-series.html" ;"title="hort for Nerve agent#G-series">G-series, "B" is an extremely toxic synthetic organophosphorus compound.Sarin (GB) Emergency Response Safety and Health Database. National Institute for Occupational Safety and Health. Accessed April 20, 2009. A colourless, odourless , it is used as a due to its extreme potency as a . Exposure is lethal even at very low concen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
