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Methylenedianiline
4,4′-Methylenedianiline (MDA) is an organic compound with the formula CH2(C6H4NH2)2. It is a colorless solid, although commercial samples can appear yellow or brown. It is produced on an industrial scale, mainly as a precursor to polyurethanes. Synthesis and applications In the industrial production, MDA is produced by reaction of formaldehyde and aniline in the presence of hydrochloric acid. MDA is consumed mainly as a precursor to Methylene diphenyl diisocyanate (MDI). MDA is treated with phosgene to produce MDI. MDI is a precursor to many polyurethane foams. Lower quantities are used as hardeners in epoxy resins and adhesives, as well as in the production of high-performance polymers. Additionally, hydrogenation of MDA can be performed to produce 4,4,diaminodicyclohexylmethane, which is also used in polymer chemistry. Safety MDA is considered a potential occupational carcinogen by the US National Institute for Occupational Safety and Health. The Occupational Safe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4,4'-Diaminodicyclohexylmethane
4,4'-Diaminodicyclohexylmethane is the name for organic compounds with the formula CH2(C6H10NH2)2. It is classified as a diamine. In the epoxy industry it is often referred to as PACM, short for ''para''-diaminodicyclohexylmethane. It is used as a curing agent for epoxy resins It finds particular use in epoxy flooring. Another use is to produce diisocyanates, which are precursors to polyurethane. The mixture is a colorless solid, but typical samples are yellowish and oily. The compound is produced as a mixture of three isomers by the hydrogenation of methylenedianiline. These isomers are, in decreasing order of their yield from the hydrogenation, trans-trans, cis-trans, and a small amount of cis-cis. Uses This diamine is mainly used to make epoxy resin curing agents for CASE (Coatings, Adhesives, Sealants, and Elastomers) applications especially flooring. Another application arises from its reaction with phosgene to produce a cycloaliphatic diisocyanate Hydrogenated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amine
In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group (these may respectively be called alkylamines and arylamines; amines in which both types of substituent are attached to one nitrogen atom may be called alkylarylamines). Important amines include amino acids, biogenic amines, trimethylamine, and aniline; Inorganic derivatives of ammonia are also called amines, such as monochloramine (). The substituent is called an amino group. Compounds with a nitrogen atom attached to a carbonyl group, thus having the structure , are called amides and have different chemical properties from amines. Classification of amines Amines can be classified according to the nature and number of substituents on nitrogen. Aliphatic amines contain only H and alkyl substituents. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SVHC
A substance of very high concern (SVHC) is a chemical substance (or part of a group of chemical substances) concerning which it has been proposed that use within the European Union be subject to authorisation under the REACH Regulation. Indeed, listing of a substance as an SVHC by the European Chemicals Agency (ECHA) is the first step in the procedure for authorisation or restriction of use of a chemical. The first list of SVHCs was published on 28 October 2008 and the list has been updated many times to include new candidates. The most recent update occurred in January 2022 to include a total of 223 SVHC. Criteria The criteria are given in article 57 of the REACH Regulation. A substance ''may'' be proposed as an SVHC if it meets one or more of the following criteria: *it is carcinogenic; *it is mutagenic; *it is toxic for reproduction; *it is persistent, bioaccumulative and toxicAnnex XIII, REACH Regulation, at pp. 383–85. (PBT substances); *it is very persistent and very bio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dapsone
Dapsone, also known as 4,4'-sulfonyldianiline (SDA) or diaminodiphenyl sulfone (DDS), is an antibiotic commonly used in combination with rifampicin and clofazimine for the treatment of leprosy. It is a second-line medication for the treatment and prevention of pneumocystis pneumonia and for the prevention of toxoplasmosis in those who have poor immune function. Additionally, it has been used for acne, dermatitis herpetiformis, and various other skin conditions. Dapsone is available both topically and by mouth. Severe side effects may include a decrease in blood cells, red blood cell breakdown especially in those with glucose-6-phosphate dehydrogenase deficiency (G-6-PD), or hypersensitivity. Common side effects include nausea and loss of appetite. Other side effects include liver inflammation, methemoglobinemia, and a number of types of skin rashes. While the safety of use during pregnancy is not entirely clear some physicians recommend that it be continued in those with l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4,4'-Oxydianiline
4,4′-Oxydianiline (ODA) is an organic compound with the formula O( C6 H4 NH2)2. It is an ether derivative of aniline. This colourless solid is a useful monomer and cross-linking agent for polymers, especially the polyimides, such as Kapton. Uses 4,4′-Oxydianiline is used in the production of a wide variety of polymer resins. The primary use lies in the production of polyimide and poly(ester)imide resins. These resins are used for their temperature-resistant properties and are utilized in products including wire enamels, coatings, film, adhesives, insulating varnishes, coated fabrics, flame-retardant fibers, oil sealants and retainers, insulation for cables and printed circuits, and laminates and composite for aerospace vehicles. Other applications of 4,4′-oxydianiline include the production of poly(amide)imide resins (which are used in the manufacture of heat-resistant wire enamels and coatings), as an intermediate in the manufacture of epoxy resins and adhesives, and in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4,4'-Thiodianiline
4,4′-Thiodianiline (TDA) is the organosulfur compound with the formula (H2NC6H4)2S. It is classified as a diamine and a thioether. A colorless solid, it is used as a precursor to dyes. An analogue of TDA is dapsone. Synthesis Sulfur is boiled in excess aniline over several hours to produce three isomers (1,1′; 1,4; 4,4′) of TDA. The same journal documents syntheses of similar and overlapping compounds by Merz and Weith in 1871, and K. A. Hoffman in 1894. A study by Nietzki and Bothof shows indications that including an oxide of lead may maximize the yield of the 4,4′ variant that this page refers to. Uses TDA was used as a chemical intermediate in the production of three dyes: CI mordant yellow 16, milling red G and milling red FR, as well as the medicine Dapsone. TDA has also been used in the synthesis of polyimine vitrimers. Production TDA is no longer produced in the USA. Toxicity TDA has caused mutations in some strains of ''Salmonella typhimurium'' and has ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Essex
Essex () is a county in the East of England. One of the home counties, it borders Suffolk and Cambridgeshire to the north, the North Sea to the east, Hertfordshire to the west, Kent across the estuary of the River Thames to the south, and Greater London to the south and south-west. There are three cities in Essex: Southend, Colchester and Chelmsford, in order of population. For the purposes of government statistics, Essex is placed in the East of England region. There are four definitions of the extent of Essex, the widest being the ancient county. Next, the largest is the former postal county, followed by the ceremonial county, with the smallest being the administrative county—the area administered by the County Council, which excludes the two unitary authorities of Thurrock and Southend-on-Sea. The ceremonial county occupies the eastern part of what was, during the Early Middle Ages, the Anglo-Saxon Kingdom of Essex. As well as rural areas and urban areas, it forms ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epping, Essex
Epping is a market town and civil parish in the Epping Forest district of the County of Essex, England. The town is northeast from the centre of London, is surrounded by the northern end of Epping Forest, and on a ridge of land between the River Roding and River Lea valleys. Epping is the terminus for London Underground's Central line. The town has a number of historic Grade I and II and Grade III listed buildings. The weekly market, which dates to 1253, is held each Monday. In 2001 the parish had a population of 11,047 which increased to 11,461 at the 2011 Census. Epping became twinned with the German town of Eppingen in north-west Baden-Württemberg in 1981. History "Epinga", a small community of a few scattered farms and a chapel on the edge of the forest, is mentioned in the ''Domesday Book'' of 1086. However, the settlement referred to is known today as Epping Upland. It is not known for certain when the present-day Epping was first settled. By the mid-12th century a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ECHA
The European Chemicals Agency (ECHA; ) is an agency of the European Union which manages the technical and administrative aspects of the implementation of the European Union regulation called Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH). ECHA is the driving force among regulatory authorities in implementing the EU's chemicals legislation. ECHA has to ascertain that companies comply with the legislation, advances the safe use of chemicals, provides information on chemicals and addresses chemicals of concern. It is located in Helsinki, Finland. ECHA is an independent and mature regulatory agency established by REACH. It is not a subsidiary entity of the European Commission. The agency, currently headed by Acting Executive Director Shay O’Malley, started working on 1 June 2007. Establishment The ECHA was created by European Union regulation dating from 18 December 2006 to manage the then-new legislation to regulate the manufacture and use of chemic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carcinogen
A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive substances are considered carcinogens, but their carcinogenic activity is attributed to the radiation, for example gamma rays and alpha particles, which they emit. Common examples of non-radioactive carcinogens are inhaled asbestos, certain dioxins, and tobacco smoke. Although the public generally associates carcinogenicity with synthetic chemicals, it is equally likely to arise from both natural and synthetic substances. Carcinogens are not necessarily immediately toxic; thus, their effect can be insidious. Carcinogens, as mentioned, are agents in the environment capable of contributing to cancer growth. Carcinogens can be categorized into two different types: activation-dependent and activation-independent, and each nature impacts their level ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element is therefore not a compound. A compound can be transformed into a different substance by a chemical reaction, which may involve interactions with other substances. In this process, bonds between atoms may be broken and/or new bonds formed. There are four major types of compounds, distinguished by how the constituent atoms are bonded together. Molecular compounds are held together by covalent bonds; ionic compounds are held together by ionic bonds; intermetallic compounds are held together by metallic bonds; coordination complexes are held together by coordinate covalent bonds. Non-stoichiometric compounds form a disputed marginal case. A chemical formula specifies the number of atoms of each element in a compound molecule, using the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
