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Alexandru Balaban
Alexandru T. Balaban (born April 2, 1931 in Timișoara) is a Romanian chemist who made significant contributions to the fields of organic chemistry, theoretical chemistry, mathematical chemistry, and chemical graph theory. Early life and education Balaban was born in Timișoara, in the western part of Romania. His parents (Teodor and Florica Balaban) paid a lot of attention to Balaban's education, strongly encouraging his fascination with chemistry. In 1935 his family moved to Bucharest, where Balaban attended elementary school. After World War II, in 1945 they moved to Petroșani, where he finished high school. Alexandru Balaban enrolled the Politehnica University of Bucharest in 1949, where he was awarded a Ph.D. in chemistry on April 2, 1959. The topic of his Ph.D. thesis dealt with the restrictions catalyzed by anhydrous aluminium chloride. Career For more than forty years, Balaban held positions at the Chair of Organic Chemistry of the Politehnica University of Buchare ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alexandru T
Alexandru is the Romanian form of the name Alexander. Common diminutives are Alecu, Alex, and Sandu. Origin Etymologically, the name is derived from the Greek "Αλέξανδρος" (Aléxandros), meaning "defending men" or "protector of men", a compound of the verb "ἀλέξω" (alexō), "to ward off, to avert, to defend" and the noun "ἀνδρός" (andros), genitive of "ἀνήρ" (anēr), "man". It is an example of the widespread motif of Greek (or Indo-European more generally) names expressing "battle-prowess", in this case the ability to withstand or push back an enemy battle line. The earliest attested form of the name is the Mycenaean Greek feminine noun ''a-re-ka-sa-da-ra'', (transliterated as ''Alexandra''), written in Linear B syllabic script. The name was one of the titles ("epithets") given to the Greek goddess Hera and as such is usually taken to mean "one who comes to save warriors". In the Iliad, the character Paris is known also as Alexander. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Texas A&M University At Galveston
Texas A&M University at Galveston (TAMUG) is an ocean-oriented branch campus of Texas A&M University offering both undergraduate and graduate degrees that are awarded from Texas A&M University in College Station. Students enrolled at Texas A&M University at Galveston, known affectionately as 'Sea Aggies', share the benefits of students attending Texas A&M University (TAMU) campus in College Station. TAMUG is located on Pelican Island, offering benefits for its maritime focused majors. Academic programs are distinctively ocean-focused, and include marine biology, marine fisheries, marine engineering technology, marine sciences, marine transportation, maritime administration, maritime studies, maritime systems engineering, oceans and coastal resources, university studies (curriculum focused on marine environmental law and policy), and others (see below). It is the home of the Texas A&M Maritime Academy and has a Navy-option-only NROTC unit on campus. (Marine Corps-option NROTC ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theoretical Chemistry
Theoretical chemistry is the branch of chemistry which develops theoretical generalizations that are part of the theoretical arsenal of modern chemistry: for example, the concepts of chemical bonding, chemical reaction, valence, the surface of potential energy, molecular orbitals, orbital interactions, and molecule activation. Overview Theoretical chemistry unites principles and concepts common to all branches of chemistry. Within the framework of theoretical chemistry, there is a systematization of chemical laws, principles and rules, their refinement and detailing, the construction of a hierarchy. The central place in theoretical chemistry is occupied by the doctrine of the interconnection of the structure and properties of molecular systems. It uses mathematical and physical methods to explain the structures and dynamics of chemical systems and to correlate, understand, and predict their thermodynamic and kinetic properties. In the most general sense, it is explanation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boron
Boron is a chemical element with the symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the '' boron group'' it has three valence electrons for forming covalent bonds, resulting in many compounds such as boric acid, the mineral sodium borate, and the ultra-hard crystals of boron carbide and boron nitride. Boron is synthesized entirely by cosmic ray spallation and supernovae and not by stellar nucleosynthesis, so it is a low-abundance element in the Solar System and in the Earth's crust. It constitutes about 0.001 percent by weight of Earth's crust. It is concentrated on Earth by the water-solubility of its more common naturally occurring compounds, the borate minerals. These are mined industrially as evaporites, such as borax and kernite. The largest known deposits are in Turkey, the largest producer of boron minerals. Elemental boron is a meta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chelation
Chelation is a type of bonding of ions and molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These ligands are called chelants, chelators, chelating agents, or sequestering agents. They are usually organic compounds, but this is not a necessity, as in the case of zinc and its use as a maintenance therapy to prevent the absorption of copper in people with Wilson's disease. Chelation is useful in applications such as providing nutritional supplements, in chelation therapy to remove toxic metals from the body, as contrast agents in MRI scanning, in manufacturing using homogeneous catalysts, in chemical water treatment to assist in the removal of metals, and in fertilizers. Chelate effect The chelate effect is the greater affinity of chelating ligands for a metal ion than that of similar nonchelating (monodentate) ligands for the same metal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steric Effects
Steric effects arise from the spatial arrangement of atoms. When atoms come close together there is a rise in the energy of the molecule. Steric effects are nonbonding interactions that influence the shape ( conformation) and reactivity of ions and molecules. Steric effects complement electronic effects, which dictate the shape and reactivity of molecules. Steric repulsive forces between overlapping electron clouds result in structured groupings of molecules stabilized by the way that opposites attract and like charges repel. Steric hindrance Steric hindrance is a consequence of steric effects. Steric hindrance is the slowing of chemical reactions due to steric bulk. It is usually manifested in ''intermolecular reactions'', whereas discussion of steric effects often focus on ''intramolecular interactions''. Steric hindrance is often exploited to control selectivity, such as slowing unwanted side-reactions. Steric hindrance between adjacent groups can also affect torsiona ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steric Effects
Steric effects arise from the spatial arrangement of atoms. When atoms come close together there is a rise in the energy of the molecule. Steric effects are nonbonding interactions that influence the shape ( conformation) and reactivity of ions and molecules. Steric effects complement electronic effects, which dictate the shape and reactivity of molecules. Steric repulsive forces between overlapping electron clouds result in structured groupings of molecules stabilized by the way that opposites attract and like charges repel. Steric hindrance Steric hindrance is a consequence of steric effects. Steric hindrance is the slowing of chemical reactions due to steric bulk. It is usually manifested in ''intermolecular reactions'', whereas discussion of steric effects often focus on ''intramolecular interactions''. Steric hindrance is often exploited to control selectivity, such as slowing unwanted side-reactions. Steric hindrance between adjacent groups can also affect torsiona ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DPPH
DPPH is a common abbreviation for the organic chemical compound 2,2-diphenyl-1-picrylhydrazyl. It is a dark-colored crystalline powder composed of stable free radical molecules. DPPH has two major applications, both in laboratory research: one is a monitor of chemical reactions involving radicals, most notably it is a common antioxidant assay, and another is a standard of the position and intensity of electron paramagnetic resonance signals. Properties and applications DPPH has several crystalline forms which differ by the lattice symmetry and melting point. The commercial powder is a mixture of phases which melts at ~130 °C. DPPH-I (m.p. 106 °C) is orthorhombic, DPPH-II (m.p. 137 °C) is amorphous and DPPH-III (m.p. 128–129 °C) is triclinic. DPPH is a well-known radical and a trap ("scavenger") for other radicals. Therefore, rate reduction of a chemical reaction upon addition of DPPH is used as an indicator of the radical nature of that r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Naphthalene
Naphthalene is an organic compound with formula . It is the simplest polycyclic aromatic hydrocarbon, and is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass. As an aromatic hydrocarbon, naphthalene's structure consists of a fused pair of benzene rings. It is best known as the main ingredient of traditional mothballs. History In the early 1820s, two separate reports described a white solid with a pungent odor derived from the distillation of coal tar. In 1821, John Kidd cited these two disclosures and then described many of this substance's properties and the means of its production. He proposed the name ''naphthaline'', as it had been derived from a kind of naphtha (a broad term encompassing any volatile, flammable liquid hydrocarbon mixture, including coal tar). Naphthalene's chemical formula was determined by Michael Faraday in 1826. The structure of two fused benzene rings was proposed by Emil Erlen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indolizine
Indolizine is an heterocyclic compound with the formula C8H7N). It is an uncommon isomer of indole with the nitrogen located at a ring fusion position. The saturated analogs are indolizidine, which are found in a variety of alkaloids such as swainsonine Swainsonine is an indolizidine alkaloid. It is a potent inhibitor of Golgi alpha-mannosidase II, an immunomodulator, and a potential chemotherapy drug. As a toxin in locoweed (likely its primary toxin) it also is a significant cause of economi .... References External links Chemical synthesis of indolizines {{heterocyclic-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Azlactone Synthesis
Oxazolone is a chemical compound and functional group, with the molecular formula C3H3NO2. It was named in-line with the Hantzsch–Widman nomenclature and is part of a large family of oxazole based compounds. There are a total of 5 structural isomers of oxazolone; 3 according to the location of the carbonyl group and 2 more according to the location of the double bound C=X (with X= N or C): *2-(3''H'')oxazolone *2-(5''H'')oxazolone *4-(5''H'')-oxazolone *5-(2''H'')-oxazolone *5-(4''H'')-oxazolone The 4-oxazolone motif, which is also formally a lactam, is present in a number of drugs ( fenozolone, thozalinone, cyclazodone, reclazepam etc.). Substituted 5-oxazolones may also be regarded as the cyclization products of ''N''- acyl α-amino acids, making them lactones, and are sometimes referred to as azlactones. See also * Münchnone * Oxazole * Oxazolidone 2-Oxazolidone is a heterocyclic organic compound containing both nitrogen and oxygen in a 5-membered ring. Oxazolidinone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aluminium Chloride
Aluminium chloride, also known as aluminium trichloride, is an inorganic compound with the formula . It forms hexahydrate with the formula , containing six water molecules of hydration. Both are colourless crystals, but samples are often contaminated with iron(III) chloride, giving a yellow color. The anhydrous material is important commercially. It has a low melting and boiling point. It is mainly produced and consumed in the production of aluminium metal, but large amounts are also used in other areas of the chemical industry. The compound is often cited as a Lewis acid. It is an example of an inorganic compound that reversibly changes from a polymer to a monomer at mild temperature. Structure Anhydrous adopts three structures, depending on the temperature and the state (solid, liquid, gas). Solid has a sheet-like layered structure with cubic close-packed chloride ions. In this framework, the Al centres exhibit octahedral coordination geometry. In contrast, has a more mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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