|
Triazabicyclodecene
Triazabicyclodecene (1,5,7-triazabicyclo .4.0ec-5-ene or TBD) is an organic compound consisting of a bicyclic guanidine. For a charge-neutral compound, it is a relatively strong base that is effective for a variety of organic transformations. TBD is colorless solid that is soluble in a variety of solvents. Reactivity As a strong base, TBD fully deprotonates most phenols, carboxylic acids, and some carbon acids. It catalyzes a variety of reactions including Michael reactions, Henry reactions, transesterification reactions, and Knoevenagel condensations. Deprotonation at the 7-position gives a particularly electron-rich ligand as manifested in the redox properties of ditungsten tetra(hpp). The conjugate acid of TBD is the preferred cation among the guanidinium hypoiodites, which are specialized oxidizing agents for various types of organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon� ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guanidines
Guanidine is the compound with the formula HNC(NH2)2. It is a colourless solid that dissolves in polar solvents. It is a strong base that is used in the production of plastics and explosives. It is found in urine predominantly in patients experiencing renal failure. A guanidine moiety also appears in larger organic molecules, including on the side chain of arginine. Structure Guanidine can be thought of as a nitrogenous analogue of carbonic acid. That is, the C=O group in carbonic acid is replaced by a C=NH group, and each OH is replaced by a group. A detailed crystallographic analysis of guanidine was elucidated 148 years after its first synthesis, despite the simplicity of the molecule. In 2013, the positions of the hydrogen atoms and their displacement parameters were accurately determined using single-crystal neutron diffraction. Production Guanidine can be obtained from natural sources, being first isolated in 1861 by Adolph Strecker via the oxidative degradation of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guanidine
Guanidine is the compound with the formula HNC(NH2)2. It is a colourless solid that dissolves in polar solvents. It is a strong base that is used in the production of plastics and explosives. It is found in urine predominantly in patients experiencing renal failure. A guanidine moiety also appears in larger organic molecules, including on the side chain of arginine. Structure Guanidine can be thought of as a nitrogenous analogue of carbonic acid. That is, the C=O group in carbonic acid is replaced by a C=NH group, and each OH is replaced by a group. A detailed crystallographic analysis of guanidine was elucidated 148 years after its first synthesis, despite the simplicity of the molecule. In 2013, the positions of the hydrogen atoms and their displacement parameters were accurately determined using single-crystal neutron diffraction. Production Guanidine can be obtained from natural sources, being first isolated in 1861 by Adolph Strecker via the oxidative degradation of an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guanidinium Hypoiodite
Ammonium hypoiodites are a class of reactive intermediates used in certain organic oxidation reactions. They consist of either ammonium itself or an alkylammonium with various substituents as cation, paired with a hypoiodite anion as the active oxidant. The hypoiodite is generated in situ from the analogous iodide reagent using peroxides, oxone, peracids, or other strong oxidizing agents. The hypoiodite is then capable of oxidizing various organic substrates. The iodide is regenerated, meaning the reaction runs with the iodide/hypoiodite as a catalyst in the presence of excess of the original strong oxidizing agent. Ammonium hypoiodites are capable of oxidizing benzylic methyl groups, initiating oxidative dearomatization, and oxidative decarboxylation of β-ketolactones. Similar to the β-ketolactone reaction, oxidative ether formation can be performed at the alpha position of various ketones. Using chiral ammonium cations can give high enantioselectivity of the alpha-etherificati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sigma-Aldrich
Sigma-Aldrich (formally MilliporeSigma) is an American chemical, life science, and biotechnology company owned by the multinational chemical conglomerate Merck Group. Sigma-Aldrich was created in 1975 by the merger of Sigma Chemical Company and Aldrich Chemical Company. It grew through various acquisitions until it had over 9,600 employees and was listed on the Fortune 1000. The company has two United States headquarters, in St. Louis and Burlington, MA and has operations in approximately 40 countries. In 2015, the multinational chemical conglomerate Merck Group acquired Sigma-Aldrich for $17 billion. The company is currently a part of Merck's life science business and in combination with Merck's earlier acquired Millipore Corporation, Millipore, operates as MilliporeSigma. It is headquartered in Burlington, Massachusetts, United States. History Sigma Chemical Company of St. Louis and Aldrich Chemical Company of Milwaukee were both American specialty chemical companies when they ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ligand
In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electron pairs, often through Lewis acids and bases, Lewis bases. The nature of metal–ligand bonding can range from covalent bond, covalent to ionic bond, ionic. Furthermore, the metal–ligand bond order can range from one to three. Ligands are viewed as Lewis bases, although rare cases are known to involve Lewis acids and bases, Lewis acidic "ligands". Metals and metalloids are bound to ligands in almost all circumstances, although gaseous "naked" metal ions can be generated in a high vacuum. Ligands in a complex dictate the reactivity (chemistry), reactivity of the central atom, including ligand substitution rates, the reactivity of the ligands themselves, and redox. Ligand selection requires critical consideration in many practical are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catalysts
Catalysis () is the increase in reaction rate, rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quickly, very small amounts of catalyst often suffice; mixing, surface area, and temperature are important factors in reaction rate. Catalysts generally react with one or more reactants to form reaction intermediate, intermediates that subsequently give the final reaction product, in the process of regenerating the catalyst. The rate increase occurs because the catalyst allows the reaction to occur by an alternative mechanism which may be much faster than the noncatalyzed mechanism. However the noncatalyzed mechanism does remain possible, so that the total rate (catalyzed plus noncatalyzed) can only increase in the presence of the catalyst and never decrease. Catalysis may be classified as either homogeneous catalysis, homogeneou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
7-Methyl-TBD
7-Methyl-1,5,7-triazabicyclo .4.0ec-5-ene (mTBD) is a bicyclic strong guanidine base (p''K''a = 25.43 in CH3CN and p''K''a = 17.9 in THF). mTBD, like 1,5,7-triazabicyclo .4.0ec-5-ene and other guanidine super bases, can be used as a catalyst in a variety of chemical reactions. It also reacts with CO2, which could make it useful for carbon capture and storage. When brought into contact with some acids, mTBD reacts to form an ionic liquid. Some of these ionic liquids can dissolve cellulose Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important s .... References {{DEFAULTSORT:Methyl-1,5,7-triazabicyclo(4.4.0)dec-5-ene, 7- Catalysts Guanidines Pyrimidopyrimidines Amines Reagents for organic chemistry Superbases ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxidizing Agent
An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ''electron donor''). In other words, an oxidizer is any substance that oxidizes another substance. The oxidation state, which describes the degree of loss of electrons, of the oxidizer decreases while that of the reductant increases; this is expressed by saying that oxidizers "undergo reduction" and "are reduced" while reducers "undergo oxidation" and "are oxidized". Common oxidizing agents are oxygen, hydrogen peroxide, and the halogens. In one sense, an oxidizing agent is a chemical species that undergoes a chemical reaction in which it gains one or more electrons. In that sense, it is one component in an oxidation–reduction (redox) reaction. In the second sense, an oxidizing agent is a chemical species that transfers electronegative atoms, usually oxygen, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cation
An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convention. The net charge of an ion is not zero because its total number of electrons is unequal to its total number of protons. A cation is a positively charged ion with fewer electrons than protons (e.g. K+ ( potassium ion)) while an anion is a negatively charged ion with more electrons than protons (e.g. Cl− ( chloride ion) and OH− ( hydroxide ion)). Opposite electric charges are pulled towards one another by electrostatic force, so cations and anions attract each other and readily form ionic compounds. Ions consisting of only a single atom are termed ''monatomic ions'', ''atomic ions'' or ''simple ions'', while ions consisting of two or more atoms are termed polyatomic ions or ''molecular ions''. If only a + or − is present, it indic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conjugate Acid
A conjugate acid, within the Brønsted–Lowry acid–base theory, is a chemical compound formed when an acid gives a proton () to a base—in other words, it is a base with a hydrogen ion added to it, as it loses a hydrogen ion in the reverse reaction. On the other hand, a conjugate base is what remains after an acid has donated a proton during a chemical reaction. Hence, a conjugate base is a substance formed by the removal of a proton from an acid, as it can gain a hydrogen ion in the reverse reaction. Because some acids can give multiple protons, the conjugate base of an acid may itself be acidic. In summary, this can be represented as the following chemical reaction: \text + \text \; \ce \; \text + \text Johannes Nicolaus Brønsted and Martin Lowry introduced the Brønsted–Lowry theory, which said that any compound that can give a proton to another compound is an acid, and the compound that receives the proton is a base. A proton is a subatomic particle in the n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
