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Organic Chemistry
Published in Steven L. Hoenig, Basic Chemical Concepts and Tables, 2019
Organic compounds that have the same chemical formula but are attached to one another in different ways are called isomers. Isomers that have the same chemical formula and are attached to one another in same way but whose orientation to one another differ are called stereoisomers. There are several different types of isomers that are encountered in organic chemistry.
Per- and Polyfluoroalkyl Substances
Published in Caitlin H. Bell, Margaret Gentile, Erica Kalve, Ian Ross, John Horst, Suthan Suthersan, Emerging Contaminants Handbook, 2019
Ian Ross, Erica Kalve, Jeff McDonough, Jake Hurst, Jonathan A L Miles, Tessa Pancras
Many PFASs may comprise isomers, which are mixtures of linear and branched forms. Isomers are compounds with the same empirical chemical formula but different molecular structures, and they contain the same number of atoms of each element but have different arrangements of their atoms. PFASs may contain linear perfluoroalkyl groups, meaning that the carbon atoms in the perfluoroalkyl chain are connected together in a single straight line. There can be only one linear isomer in the perfluoroalkyl moiety for PFASs of a specific perfluoroalkyl chain length. Alternatively, branched isomers can contain multiple branches in the carbon backbone of the perfluoroalkyl moiety, meaning at least one carbon atom is bonded to more than two carbon atoms. There can be multiple branched chain isomers of each chain length, which increases with the length of the carbon chain. PFOS is reported to be routinely present in many environmental samples as a mixture of the linear isomer and 10 branched isomers (Riddell et al., 2009; Rayne and Friesen 2008), whereas 89 isomers are theoretically possible (Rayne and Friesen 2008). Examples of the structural formula of linear and branched PFOS are presented in Figure 3.3.
Mechanical and microscopic properties of alkali-activated fly-ash-stabilised construction and demolition waste
Published in European Journal of Environmental and Civil Engineering, 2023
Lihua Li, Haoqi Zhang, Henglin Xiao, Yaoyao Pei, Jinzhong Wang
The diffraction pattern of FA appears broad and wide ‘drum peak’ within the range of 15°–35° (2θ), signifying the existence of a typical amorphous phase. The ‘drum peak’ of the diffraction pattern of the mixture reduces after the alkaline activation occurs, probably caused by two reasons. The first reason could be the dilution of the construction waste soil, whereas the second reason could be the occurrence of alkaline activation reaction, which consumes the amorphous phase. The activation reaction also causes the peaks of these ridges to shift to the right, roughly between 20° and 40° (2θ), which represents the formation of hydrated calcium aluminosilicate (C-A-S-H) and hydrated sodium aluminosilicate (N-A-S-H) in the amorphous phase (Kamilla et al., 2010). At the same time, the XRD analysis detected the presence of orthorhombic calcium zeolite (Gismondine; chemical formula is CaAl2Si2O8H2O; structural formula is CaOAl2O32SiO24H2O). However, hydrated aluminosilicate was not detected; the reason may be that its amount was too small to be detected. It is mentioned in the literature (Hui et al., 2005; Wang et al., 2008; Williams & Roberts, 2009) that the zeolite phase is converted from the C, N-A-S-H gel of the amorphous phase.
Stabilisation of clay soil with polymers through electrokinetic technique
Published in European Journal of Environmental and Civil Engineering, 2022
A. R. Estabragh, M. Moghadas, A. A. Javadi, J. Abdollahi
Polyethylene oxide (PEO) is a polymer with chemical formula (–(CH2CH2O)n–) that is obtained by polymerisation of ethylene oxide. It is commercially available over a wide range of molecular weights. PEO with different molecular weights has different applications and physical properties (e.g. viscosity) due to the chain length effects. It is in liquid or low melting solid state depending on its molecular weight. Therefore, it is a compound with many applications from industrial manufacturing to medicine. It has low toxicity and is a water soluble polymer. The PEO used in this research was a white powder with melting point 65–67 °C. Its bulk density and particle size were 0.3–0.5 kg/L and 1000 um, respectively. The PEO used had a low molecular weight (200,000 g/mol) with neutral charge.
A new Co(II)-bearing coordination polymer: structural characterization and treatment effect on CVB3-induced myocarditis via suppressing inflammatory response
Published in Inorganic and Nano-Metal Chemistry, 2020
Li-Jun Yu, Dong-Song Bai, Wen-Li Tang, Fu-Long Bi, Ming Zhao, Zhi-Hu Li
Coordination polymers (CPs) are assembled from organic molecules as linkers and metal clusters as joints and often result in robust framework structures with nano-sized pores.[6] Such a modular synthetic approach can yield highly predictable 2D or 3D topologies, providing unprecedented structural control, which is seldom found in other conventional solid-state materials.[7,8] The CPs have become increasingly important materials in sustainable material chemistry. Among the many potential applications that can be extrapolated from these properties are gas storage, molecular separation, chemical catalysis, sensing, ion exchange, and biomedicine. Transition metal complexes that include multidentate aromatic ligands, with square planar N4 or N2O2 coordination, have various suitable biological properties.[9–14] Transition metal complexes play a vital role in nucleic acid chemistry due to their diverse applications such as in sequence-specific binding, as structural probes and as therapeutic agents. For instance, cobalt as a human essential element in the active site of vitamin B12, which indirectly regulates the synthesis of DNA, has attracted many biological and organometallic chemists who have investigated cobalt complexes with the aim of medical applications, due to their significant bioactivity.[15–18] In this study, by employment of the mixed-ligand approach, a new Co(II)-based coordination polymer with the chemical formula of [Co(ox)(ditb)] (1, ox = oxalic acid, ditb = 1,4-di(1H-1,2,4-triazol-1-yl)butane). The chemical composing of 1 has been studied via the elemental analysis and the structural arrangement has been probed via the single-crystal X-ray diffraction, which reveal that complex 1 features a two-dimensional (2D)-layered structure composed of a large three-dimensional voids formed by four Co(II) centers, two oxalic acid and two ditb linkage units. Furthermore, a green hand grinding technique has been implemented to reduce the particle size of the complex 1 to generate nanoscale 1 (denoted as nano 1 hereafter). In biological study, the CVB3-induced myocarditis animal model was constructed, and then, the nano 1 was injected into mice for the in vivo protection activity evaluation. The myocardial pathological score indicated that the inflammatory cell infiltration, necrosis, and interstitial edema in CVB3-induced myocarditis model were significantly alleviated by compound treatment. In addition to this, the ELISA data of the IL-1 and TNF-α suggested the compound significantly reduced the inflammatory response in myocardial tissue, which explain the protective effect of compound in myocarditis.