Ксилен
From Wikimedia Commons, the free media repository. Reasonator PetScan Scholia Statistics. Hiru isomero ditu. Subcategories This category has the following 3 subcategories, out of 3 total.
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Видео урок: Химични формули
With the formula CH 3 2 C 6 H 4 , each of the three compounds has a central benzene ring with two methyl groups attached at substituents. They are all colorless, flammable liquids, some of which are of great industrial value. The mixture is referred to as both xylene and, more precisely, xylenes. Xylenes are an important petrochemical produced by catalytic reforming and also by coal carbonisation in the manufacture of coke fuel.
They also occur in crude oil in concentrations of about 0. Small quantities occur in gasoline and aircraft fuels. Xylenes are produced mainly as part of the BTX aromatics benzene , toluene , and xylenes extracted from the product of catalytic reforming known as reformate. The xylene mixture is a slightly greasy, colorless liquid commonly encountered as a solvent.
Several million tons are produced annually. Xylene was first isolated and named in by the French chemist Auguste Cahours — , having been discovered as a constituent of wood tar. Xylene exists in three isomeric forms. The isomers can be distinguished by the designations ortho - o - , meta - m - and para - p - , which specify to which carbon atoms of the benzene ring the two methyl groups are attached.
By counting the carbon atoms around the ring starting from one of the ring carbons bonded to a methyl group, and counting towards the second methyl group, the o -isomer has the IUPAC name of 1,2-dimethylbenzene, the m -isomer is 1,3-dimethylbenzene and the p -isomer is 1,4-dimethylbenzene. Of the three isomers, the p -isomer is the most industrially sought after since it can be oxidized to terephthalic acid.
Xylenes are produced by the methylation of toluene and benzene. These conversions are catalyzed by zeolites. ZSM-5 is used to facilitate some isomerization reactions leading to mass production of modern plastics. The chemical and physical properties of xylene differ according to the respective isomers.
The density of each isomer is around 0. Xylene in air can be smelled at concentrations as low as 0. Xylenes form azeotropes with water and a variety of alcohols. The demand for isophthalic acid is relatively modest so m -xylene is rarely sought and hence the utility of its conversion to the o - and p -isomers. Xylene is used as a solvent. In this application, with a mixture of isomers, it is often referred to as xylenes or xylol.
Solvent xylene often contains a small percentage of ethylbenzene. Like the individual isomers, the mixture is colorless, sweet-smelling, and highly flammable. Areas of application include the printing , rubber , and leather industries. It is a common component of ink, rubber , and adhesives. In dentistry, xylene can be used to dissolve gutta percha , a material used for endodontics root canal treatments.
In the petroleum industry, xylene is also a frequent component of paraffin solvents, used when the tubing becomes clogged with paraffin wax. For similar reasons, it is often the active ingredient in commercial products for ear wax cerumen removal. Xylene is used in the laboratory to make baths with dry ice to cool reaction vessels, [15] and as a solvent to remove synthetic immersion oil from the microscope objective in light microscopy.
After staining, microscope slides are put in xylene prior to mounting with a coverslip. Although conversion to terephthalic acid is the dominant chemical conversion, xylenes are precursors to other chemical compounds. For instance chlorination of both methyl groups gives the corresponding xylene dichlorides bis chloromethyl benzenes whilst mono-bromination yields xylyl bromide , a tear gas agent used in World War I.
The principal mechanism of detoxification is oxidation to methylbenzoic acid and hydroxylation to hydroxylene. The main effect of inhaling xylene vapor is depression of the central nervous system CNS , with symptoms such as headache, dizziness, nausea and vomiting. Long-term exposure may lead to headaches, irritability, depression, insomnia, agitation, extreme tiredness, tremors, hearing loss, impaired concentration and short-term memory loss.
There is very little information available that isolates xylene from other solvent exposures in the examination of these effects. Hearing disorders have been also linked to xylene exposure, both from studies with experimental animals, [21] [22] as well as clinical studies.
Xylene is also a skin irritant and strips the skin of its oils, making it more permeable to other chemicals. The use of impervious gloves and masks, along with respirators where appropriate, is recommended to avoid occupational health issues from xylene exposure.
Xylenes are metabolized to methylhippuric acids. From Wikipedia, the free encyclopedia. The three possible xylene isomers: o -xylene , m -xylene , and p -xylene. From p. Accessed United States Environmental Protection Agency.
Retrieved 8 February J Oral Maxillofac Pathol. Analytical Chemistry. UC Davis Chem Wiki. Histotechnology: A Self-Instructional Text 3 ed. American Society for Clinical Pathology Press.
Journal of Oral and Maxillofacial Pathology. Archived from the original PDF on October 22, July Ear and Hearing. April November Journal of the American Academy of Audiology. International Archives of Occupational and Environmental Health. Occupational and Environmental Medicine. Categories : Alkylbenzenes Hazardous air pollutants Hydrocarbon solvents Soil contamination Commodity chemicals Petrochemicals Aromatic solvents Occupational safety and health.
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Namespaces Article Talk. Views Read Edit View history. In other projects Wikimedia Commons. By using this site, you agree to the Terms of Use and Privacy Policy. Systematic name. CAS number. Density and phase. Soluble in non-polar solvents such as aromatic hydrocarbons. Xylenes [9].
EU classification. Toluene , mesitylene , benzene , ethylbenzene. Wikimedia Commons has media related to Xylenes.
Тези 15 растения отстраняват токсините, според NASA
Последна актуализация: Агар-агар, прах. Загуби при сушене o C, 5 ч. Адипинова киселина , Fluka - кат. Температура на топене: 15 2 — о С. Парно налягане: 0, hPa 18,5 o C. R: 36; S:
Category:Xylenes
Мениджър Мениджър. Антуриум Anthurium andraeanum. Овлажнява въздуха, като го насища с водни пари. Това растение също поглъща ксилол и толуол и ги превръща в безвредни вещества. Както показва изследването, въздухът в помещенията съдържа голям брой вредни вещества като бензен, трихоретилен, амоняк и др. Ето и топ 15 на растенията, които може да посадите в дома си, за да намалите вредния ефект от тези замърсители. Едно от най-добрите растения, които виреят на сянка. Но имайте предвид: растението е отровно и трябва да се пази от деца и животни.
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Препарат Ксилен — это средство для лечения ринитов местного воздействия, часто используемое в ЛОР практике. Ксилен выпускается в виде капель, предназначенных для закапывания в носовые ходы. Препарат продается во флаконах из полиэтиленового материала объемом 10 мл. На кончике флаконе располагается специально встроенная насадка в виде капельницы, чтобы пациенту удобно было рассчитывать дозу. К препарату прилагается подробная инструкция, которую следует внимательно изучить перед началом терапии.
Category:Xylometazoline
Здравейте,някой има ли готови шаблони или дали може да изработи по тези модели. Трябват ми за сладкарство да не са от хартия. Моля за съвет. Ще си продавам плотера които още стои в кашон. Jump to.
12 стайни растения, с които се диша по-лесно
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Когато в края на те години, специалисти от НАСА са изследвали различни начини за пречистване на въздуха в помещения в космоса, те открили, че някои стайни растения могат да филтрират въздуха. За наше щастие, растенията могат да ни осигурят чист въздух в затворени помещения и на Земята, който понякога е много по-замърсен от външния въздух. Снимка: mnn. Лилията на мира може да се пребори и с толуен и ксилен. Това растение е светлолюбиво сукулентно и лесно се отглежда.
From Wikimedia Commons, the free media repository. Trace amine-associated receptor 4 agonist. Reasonator PetScan Scholia Statistics. Media in category "Xylometazoline" The following 6 files are in this category, out of 6 total. Nasal spray. Xylometazoline ball-and-stick animation.
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Поздравте меня у меня родился сын!
Да, действительно. Так бывает.
Браво, мне кажется это блестящая мысль