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Alkyl Halides and Substitution Reactions
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
A substitution reaction is characterized by one atom or group replacing another atom or group at an sp3-atom (usually carbon). This transformation is made possible by the presence of a polarized bond in an alkyl halide (C—Cl, C—Br, or C—I), where the carbon is electron deficient and has a polarity of δ+. That carbon is most likely to react with an electron donating species. What is a nucleophile?
Preparation of macroporous ion-exchange resin organic amine composite material by using waste plastics and its application in CO2 capture
Published in Environmental Technology, 2023
Xinmin Liu, Yanjie Niu, Yuqing Huang, Xuexia Qiu, Qingjie Guo
Optimised structures of the electrostatic potential are shown in Figure 8. The red and blue colours indicate the negative and positive regions, respectively. The darker the colour, the greater the absolute value of the electrostatic potential. In the electrostatic potential diagram of polybutadiene-polystyrene, the H atom of meta position on the benzene ring is darker red, and the negative electrostatic potential is larger. The more susceptible to attack by the electrophile, the electrophilic substitution reaction occurs, and MCER was prepared. In the MCER electrostatic potential diagram, the –SO3Na of MCER has a strong positive potential and is vulnerable to the attack group with negative potential. The electron energy of MCER-DEA is calculated to be 1.14 ev (1 ev=96.5 kJ/mol) by formula 2, indicating that MCER formed an acid–base coordination with DEA, and MCER-DEA was prepared.
New experimental low-cost nanoscience technology for formulation of silver nanoparticles-activated carbon composite as a promising antiviral, biocide, and efficient catalyst
Published in Journal of Experimental Nanoscience, 2022
H. A. Fetouh, H. M. Abd-Elnaby, M. S. Alsubaie, E. R. Sallam
The zero valent silver nanoparticle (Ag0) binding Ar–Cl giving organometallic (Ag0–Ar) complexes that are thermally stable due to the presence of fluoro atom at para position and absence of H atom in β position. Activated carbon is a conventional adsorbent [70], while AgNPs@AC is a nonconventional adsorbent but it is effective catalyst. For the above nucleophilic substitution reaction: addition of hydrazine (double nucleophile and removal of chloride ion leaving group occurs following mechanism of Zwitter ion and Meisenheimer complex (MC) depending on structural geometry of reactants and products. Bond length (C–Cl) reaction center, make hydrazination reaction followed second-order kinetics. Chloride abstraction occurs in rapid step, hydrazine attack ipso carbon carry chloride ion. In NO2 group, the nitrogen atom is more electron negative than the oxygen atom. This SNAr of the activated substrate occurs through addition–elimination or nucleophilic substitution mechanism (Ad–E, SNAr), Schemes 2 and 3.
Anisotropic derivatives of (-)-L-lactic acid and their nanocomposites
Published in Liquid Crystals, 2018
V. S. Bezborodov, S. G. Mikhalyonok, N. M. Kuz’menok, A. S. Arol, G. A. Shandryuk, A. S. Merekalov, O. A. Otmakhova, G. N. Bondarenko, R. V. Talroze
The esterification of (S)-2-(4-bromobutyloxy)propionic acid (13a) with 4-hydroxy-4ʹ-cyanobiphenyl (16) and hydroxy derivatives (8b,c) in the presence of dicyclohexylcarbodiimide afforded 4-cyano-4ʹ-biphenyl (17) and aryl ethers of (S)-2-(4-bromobutyloxy)propionic acid (18b,c), which were isolated and purified by column chromatography (see Scheme 6). The synthesised 4-cyano-4ʹ-biphenyl (S)-2-(4-bromobutyloxy)propionate (17) was used as a substrate in the nucleophilic substitution reaction with lithium acrylate for the preparation of modified monomeric ester (19). However, it was not possible to obtain the needed monomer (19) under the experimental conditions. 4-Cyano-4ʹ-biphenyl ester of acrylic acid (22) was isolated as the main product of this reaction. This unexpected result may have been due to the presence of water in the reaction mixture causing the hydrolysis of lithium acrylate and the formation of lithium hydroxide, the presence of which promotes the decomposition of aryl ethers (17 and 19). The phenolate anion (21), which is a strong enough nucleophile, is formed as a result of these transformations. The interaction of the phenolate anion (21) with alkyl acrylate (20) and, possibly, with ether (19) leads to the formation of the main reaction product (22).