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The Gmelin rare earths handbook lists 1522 °C and 1550 °C as two melting points given in the literature, the most recent reference [Handbook on the chemistry and physics of rare earths, vol.12 (1989)] is given with 1529 °C.
Anthracene is a solid polycyclic aromatic hydrocarbon (PAH) of formula C 14 H 10, consisting of three fused benzene rings. It is a component of coal tar . Anthracene is used in the production of the red dye alizarin and other dyes, as a scintillator to detect high energy particles, as production of pharmaceutical drugs.
Maleic anhydride is a classic substrate for Diels-Alder reactions. [9] It was used for work in 1928, on the reaction between maleic anhydride and 1,3-butadiene, for which Otto Paul Hermann Diels and Kurt Alder were awarded the Nobel Prize in 1950. It is through this reaction that maleic anhydride is converted to many pesticides and pharmaceuticals.
9,10-Dihydroanthracene is an organic compound that is derived from the polycyclic aromatic hydrocarbon anthracene. Several isomers of dihydroanthracene are known, but the 9,10 derivative is most common. It is a colourless solid that is used as a carrier of H 2 as a hydrogen-donor. [2]
Anthracene, being less aromatic (and therefore more reactive for Diels–Alder syntheses) in its central ring can form a 9,10 adduct with maleic anhydride at 80 °C and even with acetylene, a weak dienophile, at 250 °C. [32]
Citraconic acid can be produced, albeit inefficiently, by oxidation of xylene and methylbutanols. The acid displays the unusual property of spontaneously forming the anhydride, which, unlike maleic anhydride, is a liquid at room temperature. [2] Steps in conversion of citric acid to citraconic acid.
There are several current industrial methods to produce 9,10-anthraquinone: The oxidation of anthracene. Chromium(VI) is the typical oxidant. The Friedel-Crafts reaction of benzene and phthalic anhydride in presence of AlCl 3. o-Benzoylbenzoic acid is an intermediate.
The patent describes the reaction of the alkenes with excess maleic anhydride at 200 °C in an autoclave. The excess alkene is removed by distillation in vacuo, the resulting alkenyl succinic anhydride hydrolyzed with dilute sodium hydroxide solution and the disodium salt reacted with an acid to achieve an alkenebutanedioic acid.