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Green Catalysis, Green Chemistry, and Organic Syntheses for Sustainable Development
Published in Miguel A. Esteso, Ana Cristina Faria Ribeiro, A. K. Haghi, Chemistry and Chemical Engineering for Sustainable Development, 2020
Divya Mathew, Benny Thomas, K. S. Devaky
The formation of carbon–carbon bond is one of the most fundamental operations in organic chemistry. Formation of two carbon–carbon bonds in one reaction vessel is the basis of some of the most often used organic reactions like cycloaddition, annulations, and so on. The formation of three to six bonds effectively in one reaction vessel is definitely a severe challenge due to the multiplicity of reaction pathways available to reactive polyfunctional molecules and to numerous monofunctional molecules in the same reaction vessel. However, the success would provide rapid and efficient means for transforming simpler molecules into structurally much more complex, nonpolymeric, useful compounds. Over the years, various procedures have been developed for constructing three to six bonds in one-pot annulation reactions. The occurrence of imidazole moiety in natural products and pharmacologically active compounds has established a diverse array of synthetic approaches to these heterocycles. There are quite a lot of methods for the synthesis of highly substituted imidazole derivatives. The most used methods in the last decade are condensation of diones, aldehydes, primary amines and ammonia, N-alkylation of trisubstituted imidazoles, condensation of benzoin or benzoin acetate with aldehydes, and so on. The one-pot synthetic strategy offers the possibility of cost-effective and environmentally friendlier ways for large-scale synthesis of pyran annulated heterocyclic molecules of pharmaceutical interest.31
Electromechanical properties and applications of carbon nanotubes
Published in Michael J. O’Connell, Carbon Nanotubes Properties and Applications, 2018
In terms of mechanical properties, nanotubes are among the stiffest (Young’s modulus) and strongest (yield strength) materials yet measured. Their Young’s modulus is 0.64 TPa,6–8 roughly five times greater than steel, which matches theoretical predictions.9 Authors report inconsistent Young’s modulus values in the literature because some of them use the entire cross-sectional area that the nanotube occupies (as have I), while others use a ring of the thickness of graphene interlayer spacing (3.4 Å). Nanotubes are expected to withstand large strains of up to 6 to 10%.10 Some have been shown to survive up to 5.8%, which corresponds to a yield strength of 37 GPa,11 compared with ~300 MPa for steel. They are also quite flexible and can return to their original shape after bending and buckling.12 These exceptional properties can be explained by the strength of the carbon–carbon bond. They have led to interesting applications, including using a nanotube as a flexible, durable, high-aspect-ratio atomic force microscope (AFM) tip13 and electromechanical memories14 being developed by Nantero.* Some have even proposed that the unprecedented stiffness and strength could enable a space elevator,15 in which a nanotube-based cable would link a platform in geosynchronous orbit to the surface of the Earth, allowing transport to and from orbit via an elevator traversing the cable. Chapter 10 discusses nanotube mechanical properties in more detail.
Organic Chemistry Nomenclature
Published in Arthur W. Hounslow, Water Quality Data, 2018
The carbon atoms are joined to one another as chains, branched structures, or in rings. The carbon-carbon bonds may be single (sharing one electron pair), double (sharing two electron pairs), or triple (sharing three electron pairs). The most important ring structure, benzene, is one that consists of six carbon atoms and six hydrogen atoms in a planar ring. If a noncarbon atom replaces a carbon in a ring structure, the compound is called a heterocyclic compound. Most of the variation among organic compounds is caused by special groups of organic atoms attaching to the carbon atoms. They are called functional groups and contain at least one noncarbon atom. It is the presence of these groups that give organic compounds their unique properties. Organic compounds containing only carbon and hydrogen are called hydrocarbons. If they contain one or more halogen atoms they are called halogenated hydrocarbons. They may be divided into two groups, depending on whether the benzene ring is present or not. These are listed in Table 7.1.
Light, the universe and everything – 12 Herculean tasks for quantum cowboys and black diamond skiers
Published in Journal of Modern Optics, 2018
Girish Agarwal, Roland E. Allen, Iva Bezděková, Robert W. Boyd, Goong Chen, Ronald Hanson, Dean L. Hawthorne, Philip Hemmer, Moochan B. Kim, Olga Kocharovskaya, David M. Lee, Sebastian K. Lidström, Suzy Lidström, Harald Losert, Helmut Maier, John W. Neuberger, Miles J. Padgett, Mark Raizen, Surjeet Rajendran, Ernst Rasel, Wolfgang P. Schleich, Marlan O. Scully, Gavriil Shchedrin, Gennady Shvets, Alexei V. Sokolov, Anatoly Svidzinsky, Ronald L. Walsworth, Rainer Weiss, Frank Wilczek, Alan E. Willner, Eli Yablonovitch, Nikolay Zheludev
With high efficiency, and low cost, in hand, by following the scientific principle in Figure 29, solar electricity will be brought from the open field to nearby locations where it will be used for electrolysis of CO2 solutions, and the recycling of atmospheric carbon. There have been great strides in electrolysis which can produce various proportions of H2, CH4 and higher hydrocarbons as products. The carbon–carbon bond is particularly prized, since such compounds can be readily converted into diesel fuel and jet fuel. The study of such selective electrocatalytic surfaces is still in its infancy. Even if H2 were the only electrolysis product, there are industrial methods of using H2 to reduce CO2, and make useful liquid fuels, among many other materials.
Synthesis and characterization of Pd supported on methane diamine (propyl silane) functionalized Fe3O4 nanoparticles as a magnetic catalyst for synthesis of α-aminonitriles and 2-methoxy-2-phenylacetonitrile derivative via Strecker-type reaction under ambient and solvent-free conditions
Published in Inorganic and Nano-Metal Chemistry, 2021
Mingzhe Sun, Wei Liu, Wei Wu, Qun Li, Di Song, Li Yan, Majid Mohammadnia
The carbon–carbon bond formation is an essential process in organic compounds synthesis, and many procedures have been developed for accomplishing it. One of the most important procedures is the reaction of the carbonyl groups with a variety of carbon nucleophiles.[27] Acetals are a characteristic carbonyl protecting group and play a key role in natural products and in synthetic and medicinal chemistry.[43] In general, acetals have excellent stability from basic to neutral conditions and do not have any reactions with nucleophilic reagents, like organolithium reagents and Grignard reagents.