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Friedrich Krafft
Friedrich Krafft (February 21, 1852 in Bonn – June 3, 1923 in Heidelberg) was a German chemist. He studied with Friedrich August Kekulé von Stradonitz, Rudolf Clausius and Gerhard vom Rath. In colloidal chemistry, the Krafft temperature is named after him. In organic chemistry, the Krafft degradation reaction is named after him."Bradford P. Mundy, Michael G. Ellerd, Frank G. Favaloro, " Name reactions and reagents in organic synthesis", 2nd edition. Wiley and Sons, 2005, p.61. This reaction is a conversion of a carboxylic acid, typically of high molecular weight, into the next lower homolog. He also established the boiling point of noble metals and synthesised aromatic compounds containing selenium and tellurium Tellurium is a chemical element with the symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionally fou .... Selec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Friedrich Krafft (HeidICON 28697) (cropped)
Friedrich Krafft (February 21, 1852 in Bonn – June 3, 1923 in Heidelberg) was a German chemist. He studied with Friedrich August Kekulé von Stradonitz, Rudolf Clausius and Gerhard vom Rath. In colloidal chemistry, the Krafft temperature is named after him. In organic chemistry, the Krafft degradation reaction is named after him."Bradford P. Mundy, Michael G. Ellerd, Frank G. Favaloro, " Name reactions and reagents in organic synthesis", 2nd edition. Wiley and Sons, 2005, p.61. This reaction is a conversion of a carboxylic acid, typically of high molecular weight, into the next lower homolog. He also established the boiling point of noble metals and synthesised aromatic compounds containing selenium and tellurium. Selected publications * ''Kurzes Lehrbuch der Chemie'' (Short Handbook of Chemistry), Leipzig and Vienna, Franz Denticke: ** Volume 1: ''Anorgan. Chemie'' (Inorganic Chemistry); 1891Digital 3rd edition from 1898by the University and State Library Düsseldorf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homolog (chemistry)
In chemistry, homology is the appearance of homologues. A homologue (also spelled as homolog) is a compound belonging to a series of compounds differing from each other by a repeating unit, such as a methylene bridge −−, a peptide residue, etc. A homolog is a special case of an analog. Examples are alkanes and compounds with alkyl side chains of different length (the repeating unit being a methylene group -CH2-). Periodic table On the periodic table, homologous elements share many electrochemical properties and appear in the same group (column) of the table. For example, all noble gases are colorless, monatomic gases with very low reactivity. These similarities are due to similar structure in their outer shells of valence electrons. Mendeleev used the prefix eka- for an unknown element below a known one in the same group. See also * Homologous series * Analog * Congener * Structure–activity relationship The structure–activity relationship (SAR) is the rela ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1852 Births
Year 185 ( CLXXXV) was a common year starting on Friday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Lascivius and Atilius (or, less frequently, year 938 ''Ab urbe condita''). The denomination 185 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years. Events By place Roman Empire * Nobles of Britain demand that Emperor Commodus rescind all power given to Tigidius Perennis, who is eventually executed. * Publius Helvius Pertinax is made governor of Britain and quells a mutiny of the British Roman legions who wanted him to become emperor. The disgruntled usurpers go on to attempt to assassinate the governor. * Tigidius Perennis, his family and many others are executed for conspiring against Commodus. * Commodus drains Rome's treasury to put on gladiatorial spectacles and confiscates property to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scientists From Bonn
A scientist is a person who conducts scientific research to advance knowledge in an area of the natural sciences. In classical antiquity, there was no real ancient analog of a modern scientist. Instead, philosophers engaged in the philosophical study of nature called natural philosophy, a precursor of natural science. Though Thales (circa 624-545 BC) was arguably the first scientist for describing how cosmic events may be seen as natural, not necessarily caused by gods,Frank N. Magill''The Ancient World: Dictionary of World Biography'', Volume 1 Routledge, 2003 it was not until the 19th century that the term ''scientist'' came into regular use after it was coined by the theologian, philosopher, and historian of science William Whewell in 1833. In modern times, many scientists have advanced degrees in an area of science and pursue careers in various sectors of the economy such as academia, industry, government, and nonprofit environments.'''' History The roles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
19th-century German Chemists
The 19th (nineteenth) century began on 1 January 1801 ( MDCCCI), and ended on 31 December 1900 ( MCM). The 19th century was the ninth century of the 2nd millennium. The 19th century was characterized by vast social upheaval. Slavery was abolished in much of Europe and the Americas. The First Industrial Revolution, though it began in the late 18th century, expanding beyond its British homeland for the first time during this century, particularly remaking the economies and societies of the Low Countries, the Rhineland, Northern Italy, and the Northeastern United States. A few decades later, the Second Industrial Revolution led to ever more massive urbanization and much higher levels of productivity, profit, and prosperity, a pattern that continued into the 20th century. The Islamic gunpowder empires fell into decline and European imperialism brought much of South Asia, Southeast Asia, and almost all of Africa under colonial rule. It was also marked by the collapse of the larg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University And State Library Düsseldorf
The University and State Library Düsseldorf (german: Universitäts- und Landesbibliothek Düsseldorf, abbreviated ULB Düsseldorf) is a central service institution of Heinrich Heine University. Along with Bonn and Münster, it is also one of the three State Libraries of North Rhine-Westphalia. Tradition and Modernity From 1965 to 1969, the University and Library Düsseldorf gradually developed out of the Medical Academy in Düsseldorf. There is no real founding year of the ULB, but the foundation stone for an integrated library system was laid when the former State and City Library of Düsseldorf was taken over by the university in 1970 and merged with the Central Library of the former Medical Academy. Structure and Holdings The ULB consists of one central library and four decentralized locations. Management and media processing are organized centrally. Catalogues, databases, e-books and e-journals are accessible throughout the whole university as well as at home via the li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tellurium
Tellurium is a chemical element with the symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionally found in native form as elemental crystals. Tellurium is far more common in the Universe as a whole than on Earth. Its extreme rarity in the Earth's crust, comparable to that of platinum, is due partly to its formation of a volatile hydride that caused tellurium to be lost to space as a gas during the hot nebular formation of Earth.Anderson, Don L.; "Chemical Composition of the Mantle" in ''Theory of the Earth'', pp. 147-175 Tellurium-bearing compounds were first discovered in 1782 in a gold mine in Kleinschlatten, Transylvania (now Zlatna, Romania) by Austrian mineralogist Franz-Joseph Müller von Reichenstein, although it was Martin Heinrich Klaproth who named the new element in 1798 after the Latin 'earth'. Gold telluride mine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selenium
Selenium is a chemical element with the symbol Se and atomic number 34. It is a nonmetal (more rarely considered a metalloid) with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, and also has similarities to arsenic. It seldom occurs in its elemental state or as pure ore compounds in the Earth's crust. Selenium – from Greek ( 'Moon') – was discovered in 1817 by , who noted the similarity of the new element to the previously discovered tellurium (named for the Earth). Selenium is found in metal sulfide ores, where it partially replaces the sulfur. Commercially, selenium is produced as a byproduct in the refining of these ores, most often during production. Minerals that are pure selenide or selenate compounds are known but rare. The chief commercial uses for selenium today are glassmaking and pigments. Selenium is a semiconductor and is used in photocells. Applications in electronics, once important, have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noble Metals
A noble metal is ordinarily regarded as a metallic chemical element that is generally resistant to corrosion and is usually found in nature in its raw form. Gold, platinum, and the other platinum group metals ( ruthenium, rhodium, palladium, osmium, iridium) are most often so classified. Silver, copper and mercury are sometimes included as noble metals, however less often as each of these usually occurs in nature combined with sulfur. In more specialized fields of study and applications the number of elements counted as noble metals can be smaller or larger. In physics, there are only three noble metals: copper, silver and gold. In dentistry, silver is not always counted as a noble metal since it is subject to corrosion when present in the mouth. In chemistry, the term noble metal is sometimes applied more broadly to any metallic or semimetallic element that does not react with a weak acid and give off hydrogen gas in the process. This broader set includes copper, mercury, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boiling Point
The boiling point of a substance is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the surrounding environmental pressure. A liquid in a partial vacuum has a lower boiling point than when that liquid is at atmospheric pressure. A liquid at low pressure has a lower boiling point than when that liquid is at atmospheric pressure. Because of this, water boils at under standard pressure at sea level, but at at altitude. For a given pressure, different liquids will boil at different temperatures. The normal boiling point (also called the atmospheric boiling point or the atmospheric pressure boiling point) of a liquid is the special case in which the vapor pressure of the liquid equals the defined atmospheric pressure at sea level, one atmosphere. At that temperature, the vapor pressure of the liquid becomes sufficient to overcome atmosphe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carboxylic Acid
In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic acids occur widely. Important examples include the amino acids and fatty acids. Deprotonation of a carboxylic acid gives a carboxylate anion. Examples and nomenclature Carboxylic acids are commonly identified by their trivial names. They at oftentimes have the suffix ''-ic acid''. IUPAC-recommended names also exist; in this system, carboxylic acids have an ''-oic acid'' suffix. For example, butyric acid (C3H7CO2H) is butanoic acid by IUPAC guidelines. For nomenclature of complex molecules containing a carboxylic acid, the carboxyl can be considered position one of the parent chain even if there are other substituents, such as 3-chloropropanoic acid. Alternately, it can be named as a "carboxy" or "carboxylic acid" substituent on ano ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bonn
The federal city of Bonn ( lat, Bonna) is a city on the banks of the Rhine in the German state of North Rhine-Westphalia, with a population of over 300,000. About south-southeast of Cologne, Bonn is in the southernmost part of the Rhine-Ruhr region, Germany's largest metropolitan area, with over 11 million inhabitants. It is a university city and the birthplace of Ludwig van Beethoven. Founded in the 1st century BC as a Roman settlement in the province Germania Inferior, Bonn is one of Germany's oldest cities. It was the capital city of the Electorate of Cologne from 1597 to 1794, and residence of the Archbishops and Prince-electors of Cologne. From 1949 to 1990, Bonn was the capital of West Germany, and Germany's present constitution, the Basic Law, was declared in the city in 1949. The era when Bonn served as the capital of West Germany is referred to by historians as the Bonn Republic. From 1990 to 1999, Bonn served as the seat of government – but no longer capital ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
