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Raschig Hydroxylamine Process
The Raschig process for the production of hydroxylamine is one of three chemical processes developed by German chemist Friedrich Raschig. The main step in this process, patented by Raschig in 1887, is the reduction of nitrite with bisulfite towards hydroxylamine disulfonate, which is hydrolysed to hydroxylammonium sulfate. Most of the hydroxylamine produced is used in the manufacture of caprolactam, the precursor to the polymer Nylon 6. The commercially used Raschig process consists of the following steps: * ammonium carbonate solution is prepared by reacting ammonia, carbon dioxide and water *an alkaline solution of ammonium nitrite is formed by reacting ammonium carbonate solution with nitrogen oxides *ammonium nitrite is converted to hydroxylamine disulfonate with sulfur dioxide Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a colorless gas with a pungent smell that is r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroxylamine
Hydroxylamine (also known as hydroxyammonia) is an inorganic compound with the chemical formula . The compound exists as hygroscopic colorless crystals.Greenwood and Earnshaw. ''Chemistry of the Elements.'' 2nd Edition. Reed Educational and Professional Publishing Ltd. pp. 431–432. 1997. Hydroxylamine is almost always provided and used as an aqueous solution or more often as one of its salts such as hydroxylammonium sulfate, a water-soluble solid. Hydroxylamine and its salts are consumed almost exclusively to produce Nylon-6. The oxidation of to hydroxylamine is a step in biological nitrification. History Hydroxylamine was first prepared as hydroxylammonium chloride in 1865 by the German chemist Wilhelm Clemens Lossen (1838-1906); he reacted tin and hydrochloric acid in the presence of ethyl nitrate. It was first prepared in pure form in 1891 by the Dutch chemist Lobry de Bruyn and by the French chemist Léon Maurice Crismer (1858-1944). The coordination complex (zin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Process
In a scientific sense, a chemical process is a method or means of somehow changing one or more chemicals or chemical compounds. Such a chemical process can occur by itself or be caused by an outside force, and involves a chemical reaction of some sort. In an "engineering" sense, a chemical process is a method intended to be used in manufacturing or on an industrial scale (see Industrial process) to change the composition of chemical(s) or material(s), usually using technology similar or related to that used in chemical plants or the chemical industry. Neither of these definitions are exact in the sense that one can always tell definitively what is a chemical process and what is not; they are practical definitions. There is also significant overlap in these two definition variations. Because of the inexactness of the definition, chemists and other scientists use the term "chemical process" only in a general sense or in the engineering sense. However, in the "process (engine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Friedrich Raschig
Friedrich August Raschig (also called Fritz Raschig) (8 June 1863 – 4 February 1928) was a German chemist and politician. He was born in Brandenburg an der Havel. After he received his PhD in 1884 from the University of Berlin for his work with Robert Wilhelm Bunsen, he started working at the BASF company. In 1891 he opened his own chemical company in Ludwigshafen am Rhein (which still operates today as Raschig GmbH Company Website). He patented a number of chemical processes, particularly relating to s, one of which is now known as the Raschig phenol process, and nitrogen compounds—the [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrite
The nitrite polyatomic ion, ion has the chemical formula . Nitrite (mostly sodium nitrite) is widely used throughout chemical and pharmaceutical industries. The nitrite anion is a pervasive intermediate in the nitrogen cycle in nature. The name nitrite also refers to organic compounds having the –ONO group, which are esters of nitrous acid. Production Sodium nitrite is made industrially by passing a mixture of nitrogen oxides into aqueous sodium hydroxide or sodium carbonate solution: : : The product is purified by recrystallization. Alkali metal nitrites are thermally stable up to and beyond their melting point (441 °C for KNO2). Ammonium nitrite can be made from dinitrogen trioxide, N2O3, which is formally the anhydride of nitrous acid: :2 NH3 + H2O + N2O3 → 2 NH4NO2 Structure The nitrite ion has a symmetrical structure (C2v molecular point group, symmetry), with both N–O bonds having equal length and a bond angle of about 115°. In valence bond theory, it is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bisulfite
The bisulfite ion (IUPAC-recommended nomenclature: hydrogensulfite) is the ion . Salts containing the ion are also known as "sulfite lyes". Sodium bisulfite is used interchangeably with sodium metabisulfite (Na2S2O5). Sodium metabisulfite dissolves in water to give a solution of Na+. :Na2S2O5 + H2O → 2Na SO3 Structure The bisulfite anion exists in solution as a mixture of two tautomers. One tautomer has the proton attached to one of the three oxygen atoms. In the second tautomer the proton resides on sulfur. The S-protonated tautomer has ''C''3v symmetry. The O-protonated tautomer has only ''C''s symmetry. Reactions Tautomerization There exist two tautomers of bisulfite. They interconvert readily but can be characterized individually by various spectroscopic methods. They have been observed by 17O NMR spectroscopy: :HSO3− SO2(OH)− ''K'' = 4.9 Acid-base reactions Solutions of bisulfite are typically prepared by treatment of sulfur dioxide with aqueous bas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfonate
In organosulfur chemistry, a sulfonate is a salt, anion or ester of a sulfonic acid. Its formula is , containing the functional group , where R is typically an organyl group, amino group or a halogen atom. Sulfonates are the conjugate bases of sulfonic acids. Sulfonates are generally stable in water, non- oxidizing, and colorless. Many useful compounds and even some biochemicals feature sulfonates. Sulfonate salts Anions with the general formula are called sulfonates. They are the conjugate bases of sulfonic acids with formula . As sulfonic acids tend to be strong acids, the corresponding sulfonates are weak bases. Due to the stability of sulfonate anions, the cations of sulfonate salts such as scandium triflate have application as Lewis acids. A classic preparation of sulfonates is the Strecker sulfite alkylation, in which an alkali sulfite salt displaces a halide, typically in the presence of an iodine catalyst: : An alternative is the condensation of a sulfonyl ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroxylammonium Sulfate
Hydroxylammonium sulfate is the inorganic compound with the formula H3OHsub>2SO4. A colorless solid, it is the sulfate salt of hydroxylamine. It is primarily used as an easily handled form of hydroxylamine, which is a volatile liquid. Production Hydroxylammonium sulfate is prepared industrially by protonation of hydroxylamine. The latter is produced by the hydrogenation of nitric oxide using a platinum catalyst: : Another route to is the Raschig process: aqueous ammonium nitrite is reduced by and at 0 °C to yield a hydroxylamido-''N'',''N''-disulfonate anion:: : This ammonium hydroxylamine disulfonate anion is then hydrolyzed to give hydroxylammonium sulfate: : Applications Almost all hydroxylamine and its salts are used to make precursors to nylons via cyclohexanone oxime. Many aldehydes and ketones undergo the same conversion to oximes. carboxylic acids and their derivatives (e.g. esters) convert to hydroxamic acids. Isocyanates to N-hydroxyureas. Nitriles react ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caprolactam
Caprolactam (CPL) is an organic compound with the chemical formula, formula (CH2)5C(O)NH. This colourless solid is a lactam (a cyclic amide) of caproic acid. Global demand for this compound is approximately five million tons per year, and the vast majority is used to make Nylon 6 filament, fiber, and plastics. Synthesis and production Caprolactam was first described in the late 1800s when it was prepared by the cyclization of ε-aminocaproic acid, the product of the hydrolysis of caprolactam. World demand for caprolactam was estimated to reach five million tons per year for 2015. 90% of caprolactam produced is used to make filament and fiber, 10% for plastics, and a small amount is used as a chemical intermediate. Due to its commercial significance, many methods have been developed for the production of caprolactam. It was estimated that 90% of all caprolactam is synthesised from cyclohexanone (1), which is first converted to its Cyclohexanone oxime, oxime (2). Treatment of this ox ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nylon 6
Nylon 6 or polycaprolactam is a polymer, in particular semicrystalline polyamide. Unlike most other nylons, nylon 6 is not a condensation polymer, but instead is formed by ring-opening polymerization; this makes it a special case in the comparison between condensation and addition polymers. Its competition with nylon 66 and the example it set have also shaped the economics of the synthetic fibre industry. It is sold under numerous trade names including Perlon (Germany), Dederon (former East Germany), Nylatron, Capron, Ultramid, Akulon, Kapron (former Soviet Union and satellite states), Rugopa (Turkey) and Durethan. History Polycaprolactam was developed by Paul Schlack at IG Farben in late 1930s (first synthesized in 1938) to reproduce the properties of Nylon 66 without violating the patent on its production. (Around the same time, Kohei Hoshino at Toray also succeeded in synthesizing nylon 6.) It was marketed as Perlon, and industrial production with a capacity of 3,500 tons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ullmann's Encyclopedia Of Industrial Chemistry
''Ullmann's Encyclopedia of Industrial Chemistry'' is a major reference work related to Chemical industry, industrial chemistry by chemist Fritz Ullmann, first published in 1914, and exclusively in German as "Enzyklopädie der Technischen Chemie" until 1984. History Ullmann's Encyclopedia of Industrial Chemistry is a major reference work related to industrial chemistry by chemist Fritz Ullmann. Its first edition was published in German by Fritz Ullmann in 1914. The fourth edition, published 1972 to 1984, already contained 25 volumes. The fifth edition, published 1985 to 1996, was the first version available in English. In 1997, the first online version was published. The year 2014 marked its Centennial, centenary. Ullmann's Encyclopedia was in its seventh edition, in 40 volumes, including one index volume and more than 1,050 articles (200 more than the sixth edition), approximately 30,000 pages, 22,000 images, 8,000 tables, 19,000 references and 85,000 indices. Editions * 19 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammonium Carbonate
Ammonium carbonate is a chemical compound with the chemical formula . It is an ammonium salt of carbonic acid. It is composed of ammonium cations and carbonate anions . Since ammonium carbonate readily degrades to gaseous ammonia and carbon dioxide upon heating, it is used as a leavening agent and also as smelling salt. It is also known as baker's ammonia and is a predecessor to the more modern leavening agents baking soda and baking powder. It is a component of what was formerly known as sal volatile and salt of hartshorn, and produces a pungent smell when baked. It comes in the form of a white powder or block, with a molar mass of 96.09 g/mol and a density of 1.50 g/cm3. It is a strong electrolyte. Production Ammonium carbonate is produced by combining carbon dioxide and aqueous ammonia. About 80,000 tons/year were produced as of 1997. : An orthorhombic ammonium carbonate monohydrate is known (). It crystallizes in an ammonia solution exposed in a carbon dioxide-rich atmos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammonium Nitrite
Ammonium nitrite is a chemical compound with the chemical formula . It is the ammonium salt of nitrous acid. It is composed of ammonium cations and nitrite anions . It is not used in pure isolated form since it is highly unstable and decomposes into water and nitrogen, even at room temperature. Preparation Ammonium nitrite forms naturally in the air and can be prepared by the absorption of equal parts nitrogen dioxide and nitric oxide in aqueous ammonia. It can also be synthesized by oxidizing ammonia with ozone or hydrogen peroxide, or in a precipitation reaction of barium or lead nitrite with ammonium sulfate, or silver nitrite with ammonium chloride, or ammonium perchlorate with potassium nitrite Potassium nitrite (distinct from potassium nitrate) is the inorganic compound with the chemical formula . It is an ionic salt of potassium ions K+ and nitrite ions NO2−, which forms a white or slightly yellow, hygroscopic crystalline powder that .... The precipitate is filtered of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
