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Macrocyclic Receptors for Sensing the Environmentally Important Gaseous Molecules
Published in Satish Kumar, Priya Ranjan Sahoo, Violet Rajeshwari Macwan, Jaspreet Kaur, Mukesh, Rachana Sahney, Macrocyclic Receptors for Environmental and Biosensing Applications, 2022
Satish Kumar, Priya Ranjan Sahoo, Violet Rajeshwari Macwan, Jaspreet Kaur, Mukesh, Rachana Sahney
Calix[4]arene derivatives (34 and 35) involving either one or two amino acids of a particular type, at the 1,3-bridge have been employed as a coating of QCM sensor for the detection of organic amines through covalent attachment between bi-sulfur atoms and the gold. The presence of two phenylalanine and two cysteine moieties resulted in the formation of a larger bridge at the lower rim of the calix[4arenes derivative which assisted the assembly of macrocyclic sensing material onto the surface of the gold electrode in a better manner as a comparison to the calixarene derivative with just two cysteine units resulting in a smaller bridge (34) (Fig. 5.28). The sensor with (35) exhibited better sensitivity for n-butylamine as compared to iso-butylamine or tert-butylamine vapors owing to the steric hindrance which a branched amine may offer during the formation of a complex with the host molecules (Li et al. 2004; Yuan–Yuan et al. 2005).
Surface Acidity and Catalytic Activity
Published in Benny K.G. Theng, Clay Mineral Catalysis of Organic Reactions, 2018
Similarly, the intercalatability or otherwise of the indicator does not materially affect the titratability of acid sites in expanding layer silicates, such as montmorillonite. When the titrant has reacted with all accessible sites with an acid strength equal to, or greater than, the pKa of the (Hammett) indicator, the indicator would be displaced from its location at the silicate surface (Frenkel 1974). On the other hand, steric factors related to the size and shape of the amine titrant used would affect the measurement of acid sites. This situation may be illustrated by the data for kaolinite where neither indicator nor titrant would be able to intercalate. Figure 2.12 shows that the titratable acidity, measured using a series of amines in the presence of Hammett indicators, decreases in the order n-butylamine > isobutylamine > n-octylamine > tert-butylamine > n-dodecylamine. In explanation, Solomon et al. (1971) suggested that the neutralizing power of amines increased with the length of, or area covered by, the alkyl chain.
Ion-Conducting Polymers
Published in Sajith Thottathil, Sabu Thomas, Nandakumar Kalarikkal, Didier Rouxel, Advanced Polymeric Materials for Sustainability and Innovations, 2018
The first step is purification of relevant reagents. Toluene as a solvent was purified over columns of alumina and copper (Q5). Tetrahydrofuran used for block copolymer synthesis was purified over alumina column and degassed by three freeze-pump-thaw cycles before use. Propylene (Airgas, research purity) was purified over columns of BASF catalyst R3-12, BASF catalyst R3-11, and 4 Å molecular sieves. Polymethylaluminoxane (PMAO-IP, 13 wt.% Al in toluene, Akzo Nobel) was dried in vacuum to remove residual trimethyl aluminum and used as a white solid powder. Sodium azide, PEO polymers (Mn: 3, 8, 16 and 38 kg/mol; polydispersity index PDI= Mw/Mn = 1.02-1.12, where Mw is the weight-averaged molecular weight), p-toluenesulfonyl chloride, sodium hydride (60% dispersion in mineral oil), tripropargyl amine (98%), tetrakis (acetonitrile) copper (I) hexafluorophosphate (97%), 2,6-lutidine (> 99%), boranetetrahydrofuran complex (1.0 M solution in THF, stabilized with 0.005 M N-isopropyl-N-methyl-tert-butylamine), propargyl bromide solution (80 wt.% in toluene), and copper bromide were purchased from Sigma-Aldrich and used as received. Acetonitrile (HPLC grade) was obtained from Mallinckrodt Baker and used as received. Benzyl azide (94%) purchased from Alfa-Aesar was used as received. CDCl3 from Cambridge Isotope Laboratories (CIL) was used as received. Dry Tetrahydrofuran (THF) for electrolyte preparation obtained from Sigma-Aldrich was used as received in an argon-filled glove box. Dry LiTFSI obtained from Novolyte under argon was brought into the glove box, and dried under vacuum in the glove box antechamber at 120°C for 3 days prior to use.
Guanidine based copper(II) complexes: synthesis, structural elucidation, and biological evaluation
Published in Inorganic and Nano-Metal Chemistry, 2022
Muhammad Said, Hizbullah Khan, Ghulam Murtaza, Muhammad Sirajuddin, Amin Badshah, Syed Muhammad Salman, Rukhsana Gul
Organic solvents, chemicals and reagents were purchased from E. Merck, Fluka and Sigma-Aldrich. Copper(II) acetate, potassium thiocyanate, mercury(II) chloride, thionyl chloride, benzoic acid, copper(II) chloride, magnesium sulfate, 2,6-dichloroaniline, DMF, chloroform, methanol, n-hexane and p-toludine were processed without foster refinement. Triethylamine, dibutylamine, sec- butylamine, n-butylamine, isobutylamine, tert-butylamine, propylamine and isopropylamine were purified through distillation. In addition, the solvents such as alcohols, chloroform, acetone, n-hexane, dichloromethane and petroleum ether were first distilled, purified, and dried in an established manner. Finally their saturation with nitrogen, storage over molecular sieves of 4 Å and degassing was achieved.[36]
A review of the effect of biodiesel on the corrosion behavior of metals/alloys in diesel engines
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Anh Tuan Hoang, Meisam Tabatabaei, Mortaza Aghbashlo
Amine-based corrosion inhibitors, i.e., ethylenediamine (EDA), n-butylamine (nBA), and tert-butylamine (TBA) were also investigated for the cast iron-based parts of a diesel engine by Fazal, Haseeb, and Masjuki (2011b). After a 50-d SIT, the corrosion rate of grey cast iron (composition (wt.%): 3% carbon, 1.84% silica, 0.098% phosphorus, 0.089% sulfur and iron) was analyzed, and the inhibition efficiencies of the additives used were found to be EDA > TBA > nBA. In a different study, Fazal et al. (2016) explored the corrosion rates of cast iron (CI) and low carbon steel (LCS) in B100 at room temperature with (250 ppm) and without a number of additives. The achieved results indicated that tert-butylamine (TBA) inhibitor could reduce the corrosion rates of CI and LCS by 1.8 µm/y and 3.15 µm/y, respectively, compared to the TBA-free biodiesel sample. Moreover, they also claimed more significant reductions in corrosion rates of CI and LCS in response to the application of other additives such as benzotriazole (BTA), butylated-hydroxy-toluene (BHT), and Pyrogallol (PY) (Fazal et al. 2016). In a more recent investigation, the effectiveness of TBA and butylated hydroxyanisole (BHA) on copper was evaluated by Fazal et al. (2018b). They found TBA as a highly effective corrosion inhibitor for copper. The formation of nitrogen-based compounds (Cu(NO3)2.3H2O) on the copper surface when exposed to biodiesel was highlighted as the main reason decreasing the corrosion rate (Fazal et al. 2018b). Similarly, the formation of a layer of Fe(NO3)3.9H2O on the surface of cast iron (CI) and low carbon steel (LCS) when biodiesel was doped with TBA was claimed to have increased the resistance of the mentioned metals/alloys to biodiesel-caused corrosion (Fazal et al. 2016). Therefore, it could be concluded that amine-based corrosion inhibitors are capable of creating an effective barrier on the metal surfaces, preventing their exposure to biodiesel and/or oxidation products and consequently, increasing their corrosion resistance. A summary of the results of different studies investigating the efficiency of various corrosion inhibitors in biodiesel is tabulated in Table 3.