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Robert Behrend
Anton Friedrich Robert Behrend (17 December 1856 – 15 September 1926) was a German analytical organic chemist who made pioneering studies of stereochemistry and isomerism. He was also the first to synthesize uric acid and introduced potentiometric titration. The Behrend rearrangement reaction of nitrones is named after him. Behrend was born in Harburg to Karl, a trader and his wife Louise Elisabeth Margarethe Carol née Himbeck. He grew up in Hamburg. He joined the infantry regiment in 1876 and studied law for some time and then shifted to physics under Emil Gabriel Warburg. In 1877-78 he tried to study chemistry at Leipzig under Herman Kolbe but was not accepted as he knew nothing. He then worked under Gustav Heinrich Wiedemann and received a doctorate in organic chemistry in 1881. He became a professor in 1889 and in 1897, he moved to the Technical College of Hannover working on stereochemistry. He was among the first to synthesize uric acid, and cucurbituril In host-gu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harburg, Hamburg
Harburg is a Boroughs and quarters of Hamburg#Boroughs, borough of the city of Hamburg, Germany. It is also the name of Harburg (quarter), Harburg quarter in the borough, which used to be the capital of the Harburg (district), Harburg district in Lower Saxony. The borough of Harburg lies on the southern banks of the river Elbe and covers parts of the port of Hamburg as well as residential and rural areas. It had a population of 169,221 as of 2020. History Until 1937 Harburg belonged to the Prussian Province of Hanover, where it served as the capital of the Harburg (district), Harburg district. In 1927 it was merged with the nearby city of Wilhelmsburg, Hamburg, Wilhelmsburg to form the city of Harburg-Wilhelmsburg. Following the Greater Hamburg Act, Harburg was incorporated into the city of Hamburg along with several other independent cities such as Altona, Hamburg, Altona. Despite its incorporation into Hamburg, Harburg continued to be the capital of the Hanoverian district of H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potentiometric Titration
Potentiometric titration is a technique similar to direct titration of a redox reaction. It is a useful means of characterizing an acid. No indicator is used; instead the potential is measured across the analyte, typically an electrolyte solution. To do this, two electrodes are used, an indicator electrode (the glass electrode and metal ion indicator electrode) and a reference electrode. Reference electrodes generally used are hydrogen electrodes, calomel electrodes, and silver chloride electrodes. The indicator electrode forms an electrochemical half cell with the interested ions in the test solution. The reference electrode forms the other half cell. The overall electric potential is calculated as Ecell = Eind - Eref + Esol. Esol is the potential drop over the test solution between the two electrodes. Ecell is recorded at intervals as the titrant is added. A graph of potential against volume added can be drawn and the end point of the reaction is halfway between the jump in volta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1926 Deaths
Nineteen or 19 may refer to: * 19 (number), the natural number following 18 and preceding 20 * one of the years 19 BC, AD 19, 1919, 2019 Films * ''19'' (film), a 2001 Japanese film * ''Nineteen'' (film), a 1987 science fiction film Music * 19 (band), a Japanese pop music duo Albums * ''19'' (Adele album), 2008 * ''19'', a 2003 album by Alsou * ''19'', a 2006 album by Evan Yo * ''19'', a 2018 album by MHD * ''19'', one half of the double album ''63/19'' by Kool A.D. * ''Number Nineteen'', a 1971 album by American jazz pianist Mal Waldron * ''XIX'' (EP), a 2019 EP by 1the9 Songs * "19" (song), a 1985 song by British musician Paul Hardcastle. * "Nineteen", a song by Bad4Good from the 1992 album '' Refugee'' * "Nineteen", a song by Karma to Burn from the 2001 album ''Almost Heathen''. * "Nineteen" (song), a 2007 song by American singer Billy Ray Cyrus. * "Nineteen", a song by Tegan and Sara from the 2007 album '' The Con''. * "XIX" (song), a 2014 song by Slipkn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1856 Births
Events January–March * January 8 – Borax deposits are discovered in large quantities by John Veatch in California. * January 23 – American paddle steamer SS ''Pacific'' leaves Liverpool (England) for a transatlantic voyage on which she will be lost with all 186 on board. * January 24 – U.S. President Franklin Pierce declares the new Free-State Topeka government in "Bleeding Kansas" to be in rebellion. * January 26 – First Battle of Seattle: Marines from the suppress an indigenous uprising, in response to Governor Stevens' declaration of a "war of extermination" on Native communities. * January 29 ** The 223-mile North Carolina Railroad is completed from Goldsboro through Raleigh and Salisbury to Charlotte. ** Queen Victoria institutes the Victoria Cross as a British military decoration. * February ** The Tintic War breaks out in Utah. ** The National Dress Reform Association is founded in the United States to promote "rational" dress for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Katharina Behrend
Katharina Eleonore Behrend (July 22, 1888 – November 15, 1973) was a German-born Dutch photographer who is remembered for a wide variety of photographic genres including a nude self-portrait. Biography Born in Leipzig, she grew up in a well-to-do family as the daughter of Robert Behrend, a chemistry professor, later moving to Hanover. She carefully recorded the photographs she took from 1904 with her father's 9 x 12 cm camera, noting shutter-speed, aperture, location and the names of the people photographed. , Nederlands Fotomuseum. Retrieved 20 March 2013. Behrend's work is archived at the Nederlands Fotomuseum. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gustav Heinrich Wiedemann
Gustav Heinrich Wiedemann (; 2 October 1826 – 24 March 1899) was a German physicist and scientific author. Life Wiedemann was born in Berlin the son of a merchant who died two years later. Following the death of his mother in 1842 he lived with his grandparents. After attending a private school as well as the Cölnische Humanistische Gymnasium, he entered the University of Berlin in 1844 where took his doctor's degree three years later under the supervision of Heinrich Gustav Magnus. His thesis on that occasion was devoted to a question in organic chemistry, for he held the opinion that the study of chemistry is an indispensable preliminary to the pursuit of physics, which was his ultimate aim. In Berlin he made the acquaintance of Hermann von Helmholtz at the house of Heinrich Gustav Magnus and was one of the founders of the Berlin Physical Society. In 1854 he left Germany to take on the role of Professor of Physics in Basel, nine years later he moved to Braunschweig and in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hermann Kolbe
Adolph Wilhelm Hermann Kolbe (27 September 1818 – 25 November 1884) was a major contributor to the birth of modern organic chemistry. He was a professor at Marburg and Leipzig. Kolbe was the first to apply the term synthesis in a chemical context, and contributed to the philosophical demise of vitalism through synthesis of the organic substance acetic acid from carbon disulfide, and also contributed to the development of structural theory. This was done via modifications to the idea of "radicals" and accurate prediction of the existence of secondary and tertiary alcohols, and to the emerging array of organic reactions through his Kolbe electrolysis of carboxylate salts, the Kolbe-Schmitt reaction in the preparation of aspirin and the Kolbe nitrile synthesis. After studies with Wöhler and Bunsen, Kolbe was involved with the early internationalization of chemistry through work in London (with Frankland). He was elected to the Royal Swedish Academy of Sciences, and won the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emil Warburg
Emil Gabriel Warburg (; 9 March 1846 – 28 July 1931) was a German physicist who during his career was professor of physics at the Universities of Strassburg, Freiburg and Berlin. He was president of the Deutsche Physikalische Gesellschaft 1899–1905. His name is notably associated with the Warburg element of electrochemistry. Among his students were James Franck (Nobel Prize in Physics, 1925), Eduard Grüneisen, Robert Pohl, Erich Regener and Hans von Euler-Chelpin (Nobel Prize in Chemistry, 1929). He carried out research in the areas of kinetic theory of gases, electrical conductivity, gas discharges, heat radiation, ferromagnetism and photochemistry. He was a member of the Warburg family, and the father of Otto Heinrich Warburg (Nobel Prize in Physiology, 1931). He was a friend of Albert Einstein. See also *Magnetic refrigeration Magnetic refrigeration is a cooling technology based on the magnetocaloric effect. This technique can be used to attain extremely low tem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harburg (quarter)
Harburg () is a quarter (''Stadtteil'') in the Harburg borough (''Bezirk'') of Hamburg, Germany. It used to be the capital of the Harburg district in Lower Saxony. In 2020, the population was 25,979. History A castle named Horeburg, meaning swamp castle, was probably erected by the counts of Stade, to secure the eastern border of the county. The oldest records mentioning the castle date back to 1133 and 1137. Outside the castle a settlement developed. As to religion Harburg belonged to the Diocese of Verden (till 1648). In 1257 the area became part of the Duchy of Brunswick and Lunenburg. After its dynastic partition in 1267 Harburg was part of the Brunswick-Lunenburgian Principality of Lunenburg (Celle). In 1288 the settlement outside the castle was granted municipal rights and in 1297 town privileges. The town was then the centre of the Bailiwick of Harburg (Vogtei Harburg). After Duke Otto (1495–1549), who co-ruled Lunenburg-Celle with his brother Duke Ernest I ''the Co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrones
In organic chemistry, a nitrone is a functional group consisting of an ''N''-oxide of an imine. The general structure is , where R’ is not a hydrogen. A nitrone is a 1,3-dipole, and is used in 1,3-dipolar cycloadditions. Other reactions of nitrones are known, including formal +3cycloadditions to form 6-membered rings, as well as formal +2cycloadditions to form 7-membered rings. Generation of nitrones Nitrones are generated most often either by the oxidation of hydroxylamines or condensation of monosubstituted hydroxylamines with carbonyl compounds (ketones or aldehydes). The most general reagent used for the oxidation of hydroxylamines is mercury(II) oxide. Carbonyl condensation methods avoid issues of site selectivity associated with the oxidation of hydroxylamines with two sets of (alpha) hydrogens. A significant problem associated with many reactive nitrones is dimerization. This issue is alleviated experimentally by employing an excess of the nitrone or increasing th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isomer
In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Isomers do not necessarily share similar chemical or physical properties. Two main forms of isomerism are structural or constitutional isomerism, in which ''bonds'' between the atoms differ; and stereoisomerism or spatial isomerism, in which the bonds are the same but the ''relative positions'' of the atoms differ. Isomeric relationships form a hierarchy. Two chemicals might be the same constitutional isomer, but upon deeper analysis be stereoisomers of each other. Two molecules that are the same stereoisomer as each other might be in different conformational forms or be different isotopologues. The depth of analysis depends on the field of study or the chemical and physical properties of interest. The English word "isomer" () is a back-for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
