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Developer (photography)
In the processing of photographic films, plates or papers, the photographic developer (or just developer) is one or more chemicals that convert the latent image to a visible image. Developing agents achieve this conversion by reducing the silver halides, which are pale-colored, into silver metal, which is black (when a fine particle).Karlheinz Keller et al. ''Photography'' in ''Ullmann's Encyclopedia of Industrial Chemistry'', 2005, Wiley-VCH, Weinheim. The conversion occurs within the gelatine matrix. The special feature of photography is that the developer acts more quickly on those particles of silver halides that have been exposed to light. Paper left in developer will eventually reduce all the silver halides and turn black. Generally, the longer a developer is allowed to work, the darker the image. Chemical composition of developers The developer typically consists of a mixture of chemical compounds prepared as an aqueous solution. For black-and-white photography, three ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antipyrin
Phenazone (INN and BAN; also known as phenazon, antipyrine (USAN), or analgesine) is an analgesic (pain reducing), antipyretic (fever reducing) and anti-inflammatory drug. While it predates the term, it is often classified as a nonsteroidal anti-inflammatory drug (NSAID). Phenazone was one of the earliest synthetic medications — when it was patented in 1883, the only synthetic medical chemicals on the market were chloral hydrate, a sedative (as well as at least one derivative of that chemical), trimethylamine, and iodol (tetraiodopyrrol), an early antiseptic. One of the earliest widely used analgesics and antipyretics, phenazone was gradually replaced in common use by other medications including phenacetin (itself later withdrawn because of safety concerns), aspirin, paracetamol and modern NSAIDs such as ibuprofen. However, it is still available in several countries either as an over-the-counter or prescribed drug. History Ludwig Knorr was the first to synthesize phenazone, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferrous Citrate
Ferrous citrate, also known as iron(II) citrate or iron(2+) citrate, describes coordination complexes containing citrate anions with Fe2+ formed in aqueous solution. Although a number of complexes are possible (or even likely), only one complex has been crystallized. That complex is the coordination polymer with the formula e(H2O)6sup>2+2.2H2O, where C6H5O73- is HOC(CH2CO2−)2(CO2−, i.e., the triple conjugate base of citric acid wherein the three carboxylic acid groups are ionized. Ferrous citrates are all paramagnetic, reflecting the weak crystal field of the carboxylate ligands. Ferrous citrates are produced by treating disodium citrate with sources of iron(II) aquo complexes, such as iron(II) sulfate. Ferrous citrates are all highly unstable in air, converting to ferric citrates. It is a nutrient supplement approved by the FDA. See also * Iron(III) citrate * Ammonium ferric citrate Ammonium ferric citrate (also known as Ferric Ammonium Citrate or Ammoniacal fe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferrous Lactate
Ferrous lactate, or iron(II) lactate, is chemical compound with idealized formula (H2O)n. No compound has been characterized to establish composition, purity, or structure. Production Iron(II) lactate can be produced through several reactions, among which are calcium lactate with iron(II) sulfate according to the following reaction: ::Ca(C3H5O3)2(aq) + FeSO4(aq)->CaSO4v + Fe(C3H5O3)2(aq) Another route yielding iron(II) lactate is to combine lactic acid with calcium carbonate and iron(II) sulfate. Uses Iron (II) lactate is used as a reagent in the production of proton-exchange membrane fuel cells (PEMFCs), specifically in the production of cathode catalytic converters used in these cells. It is an acidity regulator and, since it oxidizes on contact with air, it has found use as a color retention agent for foodstuffs such as olives. It is also used to food fortification, fortify foods with iron, as a remedy for anemia due to iron deficiency, and as a nutritional supplement in tabl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroxylamine
Hydroxylamine is an inorganic compound with the formula . The material is a white crystalline, hygroscopic compound.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. It is consumed almost exclusively to produce Nylon-6. It is also an intermediate in biological nitrification. 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 , known as Crismer's salt, releases hydroxylamine upon heating. Production Hydroxylamine or its salts can be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferrous Oxalate
Ferrous oxalate, or iron(II) oxalate, is an inorganic compound with the formula FeC2O4 where is typically 2. These are orange compounds, poorly soluble in water. Structure The dihydrate FeC2O4 is a coordination polymer, consisting of chains of oxalate-bridged ferrous centers, each with two aquo ligands. When heated, it dehydrates and decomposes into a mixture of iron oxides and pyrophoric iron metal, with release of carbon dioxide, carbon monoxide, and water. Natural occurrence Anhydrous iron(II) oxalate is as yet (2020) unknown among minerals. However, the dihydrate is known, as humboldtine. A related, though much more complex mineral is stepanovite, Na g(H2O)6Fe(C2O4)3]·3H2O - an example of trioxalatoferrate(II). See also A number of other iron oxalates are known * Iron(III) oxalate * Potassium ferrioxalate Potassium ferrioxalate, also called potassium trisoxalatoferrate or potassium tris(oxalato)ferrate(III) is a chemical compound with the formula []. It often occurs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catechol
Catechol ( or ), also known as pyrocatechol or 1,2-dihydroxybenzene, is a toxic organic compound with the molecular formula . It is the ''ortho'' isomer of the three isomeric benzenediols. This colorless compound occurs naturally in trace amounts. It was first discovered by destructive distillation of the plant extract catechin. About 20,000 tonnes of catechol are now synthetically produced annually as a commodity organic chemical, mainly as a precursor to pesticides, flavors, and fragrances. Catechol occurs as feathery white crystals that are very rapidly soluble in water. Isolation and synthesis Catechol was first isolated in 1839 by Edgar Hugo Emil Reinsch (1809–1884) by distilling it from the solid tannic preparation catechin, which is the residuum of catechu, the boiled or concentrated juice of ''Mimosa catechu'' (''Acacia catechu''). Upon heating catechin above its decomposition point, a substance that Reinsch first named ''Brenz-Katechusäure'' (burned catechu acid) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrogallol
Pyrogallol is an organic compound with the formula C6H3(OH)3. It is a water-soluble, white solid although samples are typically brownish because of its sensitivity toward oxygen. It is one of three isomers of benzenetriols. Production and reactions It is produced in the manner first reported by Scheele in 1786: heating gallic acid to induce decarboxylation. Gallic acid is also obtained from tannin. Many alternative routes have been devised. One preparation involves treating ''para''-chlorophenoldisulfonic acid with potassium hydroxide, a variant on the time-honored route to phenols from sulfonic acids. When in alkaline solution, pyrogallol undergoes deprotonation of one or more phenolic groups. Such solutions absorb oxygen from the air, turning brown. This conversion can be used to determine the amount of oxygen in a gas sample, notably by the use of the Orsat apparatus. Polyhydroxybenzenes are relatively electron-rich. One manifestation is the easy C-acetylation of pyrog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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