Dehydrogenation is a chemical reaction that involves the removal of hydrogen, usually from an organic molecule. It is slightly more stable and active than that prepared by the impregnation method. This work presents a strategy to convert the Cr(VI) pollutant in wastewater into active Cr catalysts in one step by simultaneous photoreduction and deposition using ZrO2 nanoparticles as the photocatalyst and support. Reactions classified by the term typically involve the hydrocarbon first to react with a metal catalyst to create an organometallic complex in which the hydrocarbon is coordinated to the inner-sphere of a metal, either via an intermediate "alkane or arene complex" or as a transition state leading to a "M−C" intermediate. Get article recommendations from ACS based on references in your Mendeley library. Carbon–hydrogen bond functionalization is a type of reaction in which a carbon–hydrogen bond is cleaved and replaced with a carbon–X bond. These dehydrogenation is of interest in the synthesis of fine organic chemicals. Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. The inflexibility of the pincer-metal interaction confers high thermal stability to the resulting complexes. These intermediates are essential to the production of consumer goods. Unsaturated hydrocarbons containing two or more double bonds are known as alkadienes, alkatrienes, alkatetraenes, and so on. At its simplest, it is useful way of converting alkanes, which are relatively inert and thus low-valued, to olefins, which are reactive and thus more valuable. On the laboratory scale, quinones, especially 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) are effective. Understand the Dehydration of Alcohols with E1, E2 Mechanism i.e. Low-Carbon Technology and Chemical Reaction Engineering Laboratory, School of Chemical Engineering, Sichuan University, Chengdu 610065, P. R. China, Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610065, P. R. China, Turning Waste to Resource: An Example of Dehydrogenation Catalyst Cr/ZrO. https://doi.org/10.1016/j.jphotochem.2020.112735, https://doi.org/10.1016/j.synthmet.2020.116470. Catalysts are required for the reaction to be usable; non-catalytic hydrogenation takes place only at very high temperatures. Test Your Knowledge - and learn some interesting things along the way. More from Merriam-Webster on dehydrogenation, Britannica.com: Encyclopedia article about dehydrogenation. It is important because aldehydes are easily converted into many secondary products. Find more information about Crossref citation counts. This process has undergone continuous growth since its invention: Production capacity reached 6.6×106 tons in 1995. The usual strategy to activate oxygen in a controlled manner is to use molecular hydrogen or carbon monoxide as sacrificial reductants in presence of a heterogeneous catalyst, such that the activation barrier is lowered to < 10 kJ/mol and hence milder reaction conditions are required. Dehydrogenation of amines to nitriles using a variety of reagents, such as Iodine pentafluoride (IF5). The reaction is strongly endothermic, and therefore heat must be supplied to maintain the reaction temperature. It is a colorless gas with a faint petroleum-like odor. For example, the resulting aldehydes are hydrogenated to alcohols that are converted to detergents. Delivered to your inbox! 'Nip it in the butt' or 'Nip it in the bud'. Early examples of pincer ligands were anionic with a carbanion as the central donor site and flanking phosphine donors; these compounds are referred to as PCP pincers. Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free! Herman Pines was a Russian-American chemist. Hydrogenation reduces double and triple bonds in hydrocarbons. This stability is in part ascribed to the constrained geometry of the pincer, which inhibits cyclometallation of the organic substituents on the donor sites at each end. It is usually practiced as homogeneous catalysis. Propane dehydrogenation valves Reliable valve performance is critical in a propane dehydrogenation process. Pincer ligands are chelating agents that binds tightly to three adjacent coplanar sites in a meridional configuration. Typical dehydrogenation catalysts are based on iron(III) oxide, promoted by several percent potassium oxide or potassium carbonate. After earning a degree in chemical engineering at the École Supérieure de Chimie Industrielle de Lyon in France, he worked at Universal Oil Products from 1930 to 1952. Dehydrogenation is a chemical reaction that involves the removal of hydrogen, usually from an organic molecule.It is the reverse of hydrogenation.Dehydrogenation is important, both as a useful reaction and a serious problem. Send us feedback. Potential runaway situations require robust safety valve designs to provide relief systems in case of sudden pressure or temperature increases. Aromatization is a chemical reaction in which an aromatic system is formed from a single nonaromatic precursor. For example selenium dioxide (SeO 2, 10 equiv) has been used in the presence of an acid for oxidative dehydrogenation of tetrahydro-β-carbolines 49 to afford aromatic β-carbolines 50 . Build a city of skyscrapers—one synonym at a time. (A) Successive AD with release of hydrogen gas.The catalyst liberates H 2 from both starting compound and intermediate, exemplified by dehydrogenative coupling of primary alcohols with amines to form amides. Goldberg is most known for her work in inorganic and organometallic chemistry. In organic chemistry, an alkene is an unsaturated hydrocarbon that contains a carbon–carbon double bond. “Dehydrogenation.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/dehydrogenation. Karen Ila Goldberg is an American chemist, currently the Vagelos Professor of Energy Research at University of Pennsylvania. Alkenes have two hydrogen atoms fewer than the corresponding alkane with the same number of carbon atoms. Denis H. James William M. Castor, “Styrene” in. The term usually implies that a transition metal is involved in the C-H cleavage process. Scheme 1 illustrates this process. 250–400 °C in presence of iron oxide in combination with molybdenum and/or vanadium to produce formaldehyde according to the chemical equation: [7], A variety of dehydrogenation processes have been described for organic compounds. The intermediate of this first step can then undergo subsequent reactions to produce the functionalized product. Can you spell these 10 commonly misspelled words? 2 publications. Formation of protonated alcohol, Carbocation, Alkene formation. Enzymes that catalyze dehydrogenation are called dehydrogenases. Dehydrogenation strategies in organic synthesis. Your Mendeley pairing has expired. Hongbo He, Zhuangzhu Luo, Changlin Yu. Dehydrogenation definition is - the removal of hydrogen from a chemical compound. Aside from bonds to organyl fragments or molecules, bonds to 'inorganic' carbon, like carbon monoxide, cyanide, or carbide, are generally considered to be organometallic as well. It is named after chemist and Nobel laureate Sir Geoffrey Wilkinson, who first popularized its use. You’ve supercharged your research process with ACS and Mendeley! Alkenes are precursors to aldehydes, alcohols, polymers, and aromatics. Homogeneous catalysis refers to reactions where the catalyst is in the same phase as the reactants, principally in solution. Alkane metathesis is a class of chemical reaction in which an alkane is rearranged to give a longer or shorter alkane product. The resultant Cr/ZrO2 was found to be an active catalyst for selective dehydrogenation of ethane. Article Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. Helvetica Chimica Acta 1973 , 56 (4) , 1243-1251. The first is that the most favored reaction between oxygen and hydrocarbons is combustion.
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