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Guaiacol
Guaiacol () is an organic compound with the formula C6H4(OH)(OCH3). It is a phenolic compound containing an methoxy functional group. Guaiacol appears as a viscous colorless oil, although aged or impure samples are often yellowish. It occurs widely in nature and is a common product of the pyrolysis of wood. Occurrence Guaiacol is usually derived from guaiacum or wood creosote. It is produced by a variety of plants. It is also found in essential oils from celery seeds, tobacco leaves, orange leaves, and lemon peels. The pure substance is colorless, but samples become yellow upon exposure to air and light. The compound is present in wood smoke, resulting from the pyrolysis of lignin. The compound contributes to the flavor of many substances such as whiskey and roasted coffee. Preparation The compound was first isolated by Otto Unverdorben in 1826. Guaiacol is produced by methylation of ''o''-catechol, for example using potash and dimethyl sulfate: :C6H4(OH)2 + (CH3O)2SO2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Creosote
Creosote is a category of carbonaceous chemicals formed by the distillation of various tars and pyrolysis of plant-derived material, such as wood or fossil fuel. They are typically used as preservatives or antiseptics. Some creosote types were used historically as a treatment for components of seagoing and outdoor wood structures to prevent rot (e.g., bridgework and railroad ties, see image). Samples may be found commonly inside chimney flues, where the coal or wood burns under variable conditions, producing soot and tarry smoke. Creosotes are the principal chemicals responsible for the stability, scent, and flavor characteristic of smoked meat; the name is derived . The two main kinds recognized in industry are coal-tar creosote and wood-tar creosote. The coal-tar variety, having stronger and more toxic properties, has chiefly been used as a preservative for wood; coal-tar creosote was also formerly used as an escharotic, to burn malignant skin tissue, and in dentistry, to pre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mequinol
Mequinol, MeHQ or 4-methoxyphenol, is a phenol used in dermatology and organic chemistry. Uses Dermatology Mequinol is a common active ingredient in topical drugs used for skin depigmentation. As a topical drug mequinol is often mixed with tretinoin, a topical retinoid. A common formulation for this drug is an ethanolic solution of 2% mequinol and 0.01% tretinoin by mass. Dermatologists commonly prescribe the drug to treat liver spots. Lower dosages of mequinol have been used in conjunction with a Q-switched laser to depigment skin in patients with disseminated idiopathic vitiligo. Organic chemistry In organic chemistry 4-methoxyphenol is used as a polymerisation inhibitor (e.g. acrylates or styrene monomers). Preparation 4-Methoxyphenol is produced from p-benzoquinone and methanol via a free radical reaction. Safety People can be exposed to 4-methoxyphenol in the workplace by breathing it in, skin absorption, swallowing it, skin contact, and eye contact. The Nationa ... [...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] |
Smoke
Smoke is a suspension of airborne particulates and gases emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrained or otherwise mixed into the mass. It is commonly an unwanted by-product of fires (including stoves, candles, internal combustion engines, oil lamps, and fireplaces), but may also be used for pest control ( fumigation), communication ( smoke signals), defensive and offensive capabilities in the military (smoke screen), cooking, or smoking (tobacco, cannabis, etc.). It is used in rituals where incense, sage, or resin is burned to produce a smell for spiritual or magical purposes. It can also be a flavoring agent and preservative. Smoke inhalation is the primary cause of death in victims of indoor fires. The smoke kills by a combination of thermal damage, poisoning and pulmonary irritation caused by carbon monoxide, hydrogen cyanide and other combustion products. Smoke is an aerosol (or mist) of solid particl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
O-Anisidine
''o''-Anisidine (2-anisidine) is an organic compound with the formula CH3OC6H4NH2. A colorless liquid, commercial samples can appear yellow owing to air oxidation. It is one of three isomers of the methoxy-containing aniline derivative. Production and use It is prepared via methanolysis of 2-chloronitrobenzene: :NaOCH3 + ClC6H4NO2 → CH3OC6H4NO2 + NaCl The resulting ''o''-nitroanisole is reduced to ''o''-anisidine. ''o''-Anisidine is used in the manufacture of dyes. It is nitrated to give 4-nitroanisidine. It is also a precursor to ''o''-dianisidine. One special use is as a heartwood indicator. An acid solution of ''o''-anisidine is diazotized by adding a sodium nitrite solution. This mixture is applied to the wood and by reaction with polyphenols in the heartwood a reddish brown azo dye is formed. : Safety and environmental aspects ''o''-Anisidine is a dangerous pollutant from the production of dyes. It is listed as RCRA hazardous waste Hazardous waste is w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potash
Potash () includes various mined and manufactured salts that contain potassium in water-soluble form.Potash USGS 2008 Minerals Yearbook The name derives from ''pot ash'', plant ashes or soaked in water in a pot, the primary means of manufacturing potash before the . The word '''' is derived from ''potash''. Potash is produced worldwide in amounts exceeding 90 million |
Dimethyl Sulfate
Dimethyl sulfate (DMS) is a chemical compound with formula (CH3O)2SO2. As the diester of methanol and sulfuric acid, its formula is often written as ( CH3)2 SO4 or Me2SO4, where CH3 or Me is methyl. Me2SO4 is mainly used as a methylating agent in organic synthesis. Me2SO4 is a colourless oily liquid with a slight onion-like odour (although smelling it would represent significant exposure). Like all strong alkylating agents, Me2SO4 is extremely toxic. Its use as a laboratory reagent has been superseded to some extent by methyl triflate, CF3SO3CH3, the methyl ester of trifluoromethanesulfonic acid. History Dimethyl sulfate was discovered in the early 19th century in an impure form. J. P. Claesson later extensively studied its preparation. It was investigated as a candidate for possible use chemical warfare in World War I in 75% to 25% mixture with methyl chlorosulfonate (CH3ClO3S) called "C-stoff" in Germany, or with chlorosulfonic acid called "Rationite" in France. Product ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimethyl Sulfate
Dimethyl sulfate (DMS) is a chemical compound with formula (CH3O)2SO2. As the diester of methanol and sulfuric acid, its formula is often written as ( CH3)2 SO4 or Me2SO4, where CH3 or Me is methyl. Me2SO4 is mainly used as a methylating agent in organic synthesis. Me2SO4 is a colourless oily liquid with a slight onion-like odour (although smelling it would represent significant exposure). Like all strong alkylating agents, Me2SO4 is extremely toxic. Its use as a laboratory reagent has been superseded to some extent by methyl triflate, CF3SO3CH3, the methyl ester of trifluoromethanesulfonic acid. History Dimethyl sulfate was discovered in the early 19th century in an impure form. J. P. Claesson later extensively studied its preparation. It was investigated as a candidate for possible use chemical warfare in World War I in 75% to 25% mixture with methyl chlorosulfonate (CH3ClO3S) called "C-stoff" in Germany, or with chlorosulfonic acid called "Rationite" in France. Product ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methoxyphenol
Methoxyphenol or hydroxyanisole may refer to: * 2-Methoxyphenol (guaiacol, ''o''-methoxyphenol, methylcatechol, 2-hydroxyanisole) * 3-Methoxyphenol (''m''-methoxyphenol, ''m''-guaiacol, resorcinol monomethyl ether, 3-hydroxyanisole, ''m''-hydroxyanisole) * 4-Methoxyphenol Mequinol, MeHQ or 4-methoxyphenol, is a phenol used in dermatology and organic chemistry. Uses Dermatology Mequinol is a common active ingredient in topical drugs used for skin depigmentation. As a topical drug mequinol is often mixed with treti ... (mequinol, para-guaiacol, 4-hydroxyanisole) {{Chemistry index Phenol ethers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anisole
Anisole, or methoxybenzene, is an organic compound with the formula CH3OC6H5. It is a colorless liquid with a smell reminiscent of anise seed, and in fact many of its derivatives are found in natural and artificial fragrances. The compound is mainly made synthetically and is a precursor to other synthetic compounds. It is an ether. Anisole is a standard reagent of both practical and pedagogical value. It can be prepared by the Williamson ether synthesis; sodium phenoxide is reacted with a methyl halide to yield anisole. Reactivity Anisole undergoes electrophilic aromatic substitution reaction at a faster speed than benzene, which in turn reacts more quickly than nitrobenzene. The methoxy group is an ortho/para directing group, which means that electrophilic substitution preferentially occurs at these three sites. The enhanced nucleophilicity of anisole vs. benzene reflects the influence of the methoxy group, which renders the ring more electron-rich. The methoxy group str ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methylation
In the chemical sciences, methylation denotes the addition of a methyl group on a substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replacing a hydrogen atom. These terms are commonly used in chemistry, biochemistry, soil science, and the biological sciences. In biological systems, methylation is catalyzed by enzymes; such methylation can be involved in modification of heavy metals, regulation of gene expression, regulation of protein function, and RNA processing. In vitro methylation of tissue samples is also one method for reducing certain histological staining artifacts. The reverse of methylation is demethylation. In biology In biological systems, methylation is accomplished by enzymes. Methylation can modify heavy metals, regulate gene expression, RNA processing and protein function. It has been recognized as a key process underlying epigenetics. Methanogenesis Methanogenesis, the process th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Demethylation
Demethylation is the chemical process resulting in the removal of a methyl group (CH3) from a molecule. A common way of demethylation is the replacement of a methyl group by a hydrogen atom, resulting in a net loss of one carbon and two hydrogen atoms. The counterpart of demethylation is methylation. In biochemistry In biochemical systems, the process of demethylation is catalyzed by demethylases. These enzymes oxidize N-methyl groups, which occur in histones and some forms of DNA: :R2N-CH3 + O → R2N-H + CH2O One such oxidative enzyme family is the cytochrome P450. Alpha-ketoglutarate-dependent hydroxylases are active for demethylation of DNA, operating by a similar pathway. These reactions exploit the weak C-H bond adjacent to amines. In particular, 5-methylcytosines in DNA can be demethylated by TET enzymes as illustrated in the figure. TET enzymes are dioxygenases in the family of alpha-ketoglutarate-dependent hydroxylases. A TET enzyme is an alpha-ketoglut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
