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Pyrogallol Ethers
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. Polyhydroxybenzenes are relatively electron-rich. One manifestation is the easy C-acetylation of pyrogallol. Uses It was once used in hair dyeing, dyeing of suturing materials. It also has antiseptic properties. In alkaline solution, pyrogallol undergoes deprotonation. Such solutions absorb oxygen from the air, turning brown. This conversion can be used to determine t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CRC Handbook Of Chemistry And Physics
The ''CRC Handbook of Chemistry and Physics'' is a comprehensive one-volume reference resource for science research. First published in 1914, it is currently () in its 105th edition, published in 2024. It is known colloquially among chemists as the "Rubber Bible", as CRC originally stood for "Chemical Rubber Company". As late as the 1962–1963 edition (3604 pages), the ''Handbook'' contained myriad information for every branch of science and engineering. Sections in that edition include: Mathematics, Properties and Physical Constants, Chemical Tables, Properties of Matter, Heat, Hygrometric and Barometric Tables, Sound, Quantities and Units, and Miscellaneous. ''Mathematical Tables from Handbook of Chemistry and Physics'' was originally published as a supplement to the handbook up to the 9th edition (1952); afterwards, the 10th edition (1956) was published separately as '' CRC Standard Mathematical Tables''. Earlier editions included sections such as "Antidotes of Poisons", ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroquinone
Hydroquinone, also known as benzene-1,4-diol or quinol, is an aromatic organic compound that is a type of phenol, a derivative of benzene, having the chemical formula C6H4(OH)2. It has two hydroxyl groups bonded to a benzene ring in a ''para'' position. It is a white granular solid. Substituted derivatives of this parent compound are also referred to as hydroquinones. The name "hydroquinone" was coined by Friedrich Wöhler in 1843. In 2022, it was the 268th most commonly prescribed medication in the United States, with more than 900,000 prescriptions. Production Hydroquinone is produced industrially in two main ways.Phillip M. Hudnall "Hydroquinone" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. 2005 Wiley-VCH, Weinheim. . * The most widely used route is similar to the cumene process in reaction mechanism and involves the dialkylation of benzene with propene to give 1,4-diisopropylbenzene. This compound reacts with air to afford the bis(hydrop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenidone
Phenidone (1-phenyl-3-pyrazolidinone) is an organic compound that is primarily used as a photographic developer. It has five to ten times the developing power as Metol, capable of achieving the same level of development in both less time and at a lower concentration. It also has low toxicity and unlike some other developers, does not cause dermatitis Dermatitis is a term used for different types of skin inflammation, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened ... upon skin contact.''Merck Index of Chemicals and Drugs, 9th ed.'' monograph 7115 As a developer, Phenidone is typically used in conjunction with hydroquinone for black and white photography and performs better at lower pH levels. Phenidone is Ilford's trademark for this material, which was first filed on Feb. 24, 1953, but has since expired. Although the compound was first prepared in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ascorbic Acid
Ascorbic acid is an organic compound with formula , originally called hexuronic acid. It is a white solid, but impure samples can appear yellowish. It dissolves freely in water to give mildly acidic solutions. It is a mild reducing agent. Ascorbic acid exists as two enantiomers (mirror-image isomers), commonly denoted "" (for "levo") and "" (for "dextro"). The isomer is the one most often encountered: it occurs naturally in many foods, and is one form (" vitamer") of vitamin C, an essential nutrient for humans and many animals. Deficiency of vitamin C causes scurvy, formerly a major disease of sailors in long sea voyages. It is used as a food additive and a dietary supplement for its antioxidant properties. The "" form ( erythorbic acid) can be made by chemical synthesis, but has no significant biological role. Etymology The term ''ascorbic'' means antiscruvy and denotes the ability to fight off scurvy. It is related to combating Vitamin C deficiency. History The antiscor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkali
In chemistry, an alkali (; from the Arabic word , ) is a basic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0. The adjective alkaline, and less often, alkalescent, is commonly used in English as a synonym for basic, especially for bases soluble in water. This broad use of the term is likely to have come about because alkalis were the first bases known to obey the Arrhenius definition of a base, and they are still among the most common bases. Etymology The word ''alkali'' is derived from Arabic ''al qalīy'' (or ''alkali''), meaning (see calcination), referring to the original source of alkaline substances. A water-extract of burned plant ashes, called potash and composed mostly of potassium carbonate, was mildly basic. After heating this substance with calcium hydroxide (''slaked lime''), a far more strongly basic substance known as ''caustic potash ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triethanolamine
Triethanolamine, or TEOA, is an organic compound with the chemical formula . It is a colourless, viscous liquid. It is both a tertiary amine and a triol. A triol is a molecule with three alcohol groups. Approximately 150,000 tonnes were produced in 1999. It is a colourless compound although samples may appear yellow because of impurities. Production Triethanolamine is produced from the reaction of ethylene oxide with aqueous ammonia, also produced are ethanolamine and diethanolamine. The ratio of the products can be controlled by changing the stoichiometry of the reactants. : Applications Triethanolamine is used primarily in making surfactants, such as for emulsifier. It is a common ingredient in formulations used for both industrial and consumer products. The triethanolamine neutralizes fatty acids, adjusts and buffers the pH, and solubilizes oils and other ingredients that are not completely soluble in water. Triethanolammonium salts in some cases are more soluble ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jay DeFehr
Jays are a paraphyletic grouping of passerine birds within the family (biology), family Corvidae. Although the term "jay" folk taxonomy, carries no taxonomic weight, most or all of the birds referred to as jays share a few similarities: they are small to medium-sized, usually have colorful feathers and are quite noisy. These superificial characteristics set them apart from most other corvids such as crows, ravens, jackdaws, Rook (bird), rooks and magpies, which are larger and have darker plumage. Many so-called "jays" are genetically closer to these other corvids than other jays, however. Systematics and species Jays are not a monophyletic group. Anatomical and molecular evidence indicates they can be divided into a New World and an Old World lineage (the latter including the ground jays and the piapiac), while the grey jays of the genus ''Perisoreus'' form a group of their own.http://www.nrm.se/download/18.4e32c81078a8d9249800021299/Corvidae%5B1%5D.pdf PDF fulltext The black ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
