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Ureas
image:Biotin_structure.svg, 220 px, Biotin, a water-soluble B vitamins, B vitamin, is a bicyclic urea. In chemistry, ureas are a class of organic compounds with the formula (R2N)2CO where R = H, alkyl, aryl, etc. Thus, in addition to describing the specific chemical compound urea ((H2N)2CO), urea is the name of a functional group that is found in many compounds and materials of both practical and theoretical interest. Generally ureas are colorless crystalline solids, which, owing to the presence of fewer hydrogen bonds, exhibit melting points lower than that of urea itself. Synthesis Ureas can be prepared many methods, but rarely by direct carbonation, which is the route to urea itself. Instead, methods can be classified according those that assemble the urea functionality and those that start with preformed urea. Assembly of N-substituted urea functionality Phosgenation entails the reaction of amines with phosgene, proceeding via the isocyanate (or carbamoyl chloride) as an i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Urea
Urea, also called carbamide (because it is a diamide of carbonic acid), is an organic compound with chemical formula . This amide has two Amine, amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest amide of carbamic acid. Urea serves an important role in the cellular metabolism of nitrogen-containing compounds by animals and is the main nitrogen-containing substance in the urine of mammals. ''Urea'' is Neo-Latin, , , itself from Proto-Indo-European ''*h₂worsom''. It is a colorless, odorless solid, highly soluble in water, and practically non-toxic ( is 15 g/kg for rats). Dissolved in water, it is neither acidic nor base (chemistry), alkaline. The body uses it in many processes, most notably metabolic waste#Nitrogen wastes, nitrogen excretion. The liver forms it by combining two ammonia molecules () with a carbon dioxide () molecule in the urea cycle. Urea is widely used in fertilizers as a source of nitrogen (N) and is an important ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biotin Structure
Biotin (also known as vitamin B7 or vitamin H) is one of the B vitamins. It is involved in a wide range of metabolic processes, both in humans and in other organisms, primarily related to the utilization of fats, carbohydrates, and amino acids. The name ''biotin'', borrowed from the German , derives from the Ancient Greek word (; 'life') and the suffix "-in" (a suffix used in chemistry usually to indicate 'forming'). Biotin appears as a white, needle-like crystalline solid. Chemical description Biotin is classified as a heterocyclic compound, with a sulfur-containing tetrahydrothiophene ring fused to a ureido group. A C5-carboxylic acid side chain is appended to the former ring. The ureido ring, containing the −N−CO−N− group, serves as the carbon dioxide carrier in carboxylation reactions. Biotin is a coenzyme for five carboxylase enzymes, which are involved in the catabolism of amino acids and fatty acids, synthesis of fatty acids, and gluconeogenesis. Biotinylation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetramethylurea
Tetramethylurea is the organic compound with the formula (Me2N)2CO. It is a substituted ureas, urea. This colorless liquid is used as an Protic solvent, aprotic-polar solvent, especially for aromatic compounds and is used e. g. for Grignard reagents. Tetramethylurea is a colorless liquid with mild aromatic odor. Unusual for an urea is the liquid state of tetramethylurea in a range of > 170 °C. Production It is obtained by the reaction of dimethylamine with phosgene in the presence of sodium hydroxide solution. A closely related method combines dimethylcarbamoyl chloride with excess dimethylamine. This reactions is highly exothermic. The removal of the resulting dimethylamine hydrochloride requires some effort. The reaction of diphenylcarbonate with dimethylamine in an autoclave is also effective. Tetramethylurea is formed upon the oxygenation of tetrakis(dimethylamino)ethylene (TDAE). Tetramethylurea is also a common by-product formed in Amide, amide bond fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isobutylidenediurea
Isobutylidenediurea (abbreviated IBDU) is an organic compound with the formula (CH3)2CHCH2. It is a derivative of urea (OC(NH2)2), which itself is highly soluble in water, but IBDU is not. It functions as a controlled-release fertiliser owing to its low solubility, which limits the rate of its hydrolysis to urea, which is a fast-acting fertiliser. It is produced by the condensation reaction of isobutyraldehyde and two equivalents of urea: : (CH3)2CHCHO + 2 OC(NH2)2 → (CH3)2CHCH2 + H2O The controlled-release process is the reverse of the above reaction, which only occurs after the IBDU dissolves. Related materials A number of CRF's have been developed based on urea. Related to IBDU is crotonylidene diurea (Crotodur). Simpler are various urea-formaldehyde materials such as ureaform, which consists of methylene diurea Methylene diurea (MDU) is the organic compound with the formula CH2(NHC(O)NH2)2. It is a white water-soluble solid. The compound is formed by the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bis(hydroxymethyl)urea
Bis(hydroxymethyl)urea is an organic compound with the formula OC(NHCH2OH)2. This white water-soluble solid is an intermediate in the formation of urea-formaldehyde resins. It forms upon treatment of urea with an excess of formaldehyde Formaldehyde ( , ) (systematic name methanal) is an organic compound with the chemical formula and structure , more precisely . The compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde. It is stored as ....{{ Ullmann , author = C. Nitschke , author2 = G. Scherr , title = Urea Derivatives , year = 2012, doi = 10.1002/14356007.o27_o04 References Ureas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transamidation
Transamidation is a chemical reaction in which an amide reacts with an amine to generate a new amide: :RC(O)NR'2 + HNR"2 → RC(O)NR"2 + HNR'2 The reaction is typically very slow, but it can be accelerated with Lewis acid and organometallic catalysts. Primary amides (RC(O)NH2) are more amenable to this reaction. Ureas In contrast to the reluctance of amides as substrates, urea is more susceptible to this exchange process. Transamidation is practiced, sometimes even on an industrial scale, to prepare a variety of N-substituted ureas: :(H2N)2CO + R2NH → (R2N)(H2N)CO + NH3 :(R2N)(H2N)CO + R2NH → (R2N)2CO + NH3 Methylurea, precursor to theobromine, is produced from methylamine and urea. Phenylurea is produced similarly but from anilinium chloride:{{cite journal , title=Arylureas II. Urea Method p-Ethoxyphenylurea , journal=Org. Synth. , year=1951 , volume=31 , page=11 , doi=10.15227/orgsyn.031.0011 :(H2N)2CO + 6H5NH3l → (C6H5(H)N)(H2N)CO + NH4C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBDU
Isobutylidenediurea (abbreviated IBDU) is an organic compound with the formula (CH3)2CHCH2. It is a derivative of urea (OC(NH2)2), which itself is highly soluble in water, but IBDU is not. It functions as a controlled-release fertiliser owing to its low solubility, which limits the rate of its hydrolysis to urea, which is a fast-acting fertiliser. It is produced by the condensation reaction of isobutyraldehyde and two equivalents of urea: : (CH3)2CHCHO + 2 OC(NH2)2 → (CH3)2CHCH2 + H2O The controlled-release process is the reverse of the above reaction, which only occurs after the IBDU dissolves. Related materials A number of CRF's have been developed based on urea. Related to IBDU is crotonylidene diurea (Crotodur). Simpler are various urea-formaldehyde materials such as ureaform, which consists of methylene diurea and dimethylene triurea Dimethylene triurea (DMTU) is the organic compound with the formula (H2NC(O)NHCH2NH)2CO. It is a white water-soluble solid. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biuret
Biuret ( ) is a chemical compound with the chemical formula . It is a white solid that is soluble in hot water. A variety of organic derivatives are known. The term "biuret" also describes a family of organic compounds with the chemical formula , where are hydrogen, organyl or other groups. Also known as carbamylurea, it results from the condensation of two equivalents of urea. It is a common undesirable impurity in urea-based fertilizers, as biuret is toxic to plants. Preparation and structure The parent compound can be prepared by heating urea at 150 °C for ~6 hours until it gets slightly cloudy, then recrystallizing from water. After that, it can be recrystallized repeatedly from 2% sodium hydroxide solution and water to finally get base-free crystalline needles of the monohydrate which are free of cyanuric acid. While heating, a lot of ammonia is expelled: : Under related conditions, pyrolysis of urea affords triuret . In general, organic biurets (those with alkyl or aryl gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dulcin
Dulcin is an artificial sweetener about 250 times sweeter than sugar, discovered in 1883 by the Polish chemist Józef (Joseph) Berlinerblau (27 August 1859 – 1935). It was first mass-produced about seven years later. Although it was discovered only five years after saccharin, it never enjoyed the latter compound's market success. Nevertheless, it was an important sweetener of the early 20th century and had an advantage over saccharin in that it did not possess a bitter aftertaste. Early medical tests marked the substance as safe for human consumption, and it was considered ideal for diabetics. However, an FDA study in 1951 raised many questions about its safety, resulting in its removal from the market in 1954 after animal testing revealed chronic toxicity. The FDA has also said that "the Federal Security Administrator regards these chemicals as poisonous substances which have no place in any food." In Japan, poisoning accidents by dulcin occurred frequently, and use of du ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isocyanate
In organic chemistry, isocyanate is the functional group with the formula . Organic compounds that contain an isocyanate group are referred to as isocyanates. An organic compound with two isocyanate groups is known as a diisocyanate. Diisocyanates are manufactured for the production of polyurethanes, a class of polymers. Isocyanates should not be confused with cyanate esters and isocyanides, very different families of compounds. The cyanate (cyanate ester) functional group () is arranged differently from the isocyanate group (). Isocyanides have the connectivity , lacking the oxygen of the cyanate groups. Structure and bonding In terms of bonding, isocyanates are closely related to carbon dioxide (CO2) and carbodiimides (C(NR)2). The C−N=C=O unit that defines isocyanates is planar, and the N=C=O linkage is nearly linear. In phenyl isocyanate, the C=N and C=O distances are respectively 1.195 and 1.173 Å. The C−N=C angle is 134.9° and the N=C=O angle is 173.1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theobromine
Theobromine, also known as xantheose, is the principal alkaloid of ''Theobroma cacao'' (cacao plant). Theobromine is slightly water-soluble (330 mg/L) with a bitter taste. In industry, theobromine is used as an additive and precursor to some cosmetics. It is found in chocolate, as well as in a number of other foods, including tea (''Camellia sinensis''), some American hollies ( yaupon and guayusa) and the kola nut. It is a white or colourless solid, but commercial samples can appear yellowish. Theobromine, a metabolite of caffeine, is processed in the liver into xanthine and methyluric acid, peaks in the blood 2–3 hours after ingestion due to its fat solubility, and primarily acts by inhibiting adenosine receptors with minor phosphodiesterase inhibition. It is a mild heart stimulant and bronchodilator in humans with limited central nervous system effects. It can be toxic or fatal to animals like dogs and cats due to their slower metabolism of the compound. Structu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
