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Other Modification Processes
Published in Dick Sandberg, Andreja Kutnar, Olov Karlsson, Dennis Jones, Wood Modification Technologies, 2021
Dick Sandberg, Andreja Kutnar, Olov Karlsson, Dennis Jones
When Kraft lignin from conifer woods is dissolved in an IL based on imidazolium cations, the solubility varies with the anion in the following order: (CF3SO3)− ≈ (MeSO4)2 ≫ (OAc)− > (HCOO)− ≫ Cl− ≈ Br− ≫ (BF4)− ≫ (PF6)− (Pu et al., 2007). In some cases, due to the high cost of ILs and their high viscosities, a polar organic solvent, such as dimethylsulfoxide (DMSO) or N,N-dimethylformamide (DMF), has been used to dissolve lignin (Mai et al., 2014; Pinkert et al., 2011). Other ILs that have been used include 1-butyl-4-methylpyridinium hexafluorophosphate (Pu et al., 2007) and a range of protic pyridinium ILs, such as pyridinium formate, pyridinium acetate and pyridinium propionate (Rashid et al., 2016).
Acid Zeolite Catalysis
Published in Subhash Bhatia, Zeolite Catalysis: Principles and Applications, 2020
Infrared spectroscopic studies10 of ammonia and pyridine adsorbed on solid surface make it possible to distinguish between Bronsted and Lewis acid and to assess the amounts of Bronsted and Lewis acid independenUy. For example, ammonia can adsorb on a surface physically as NH3; it can be bonded to a Lewis acid site as coordinatively bound NH3; or it can be adsorbed on a Bronsted acid site as NH4+. Each of these species is independently identifiable from its characteristic infrared (IR) adsorption bonds. Pyridine similarly adsorbs on Lewis acid sites as coordinatively bound pyridine and on Bronsted acid sites as the pyridinium ion. These two species can also be distinguished by their IR spectra, allowing the numbers of Lewis and Bronsted acid sites on a surface to be determined quantitatively.
Oxidation Reactions
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
Pyridinium chlorochromate (PCC) and pyridinium dichromate (PDC) are Cr(VI) reagents that have been structurally modified to diminish their oxidizing power and improve their solubility in organic solvents. The structures are shown in the figure. Note that pyridinium is the conjugate acid of the reaction of pyridine and a Brønsted–Lowry acid. See Section 16.6 for a discussion of heteroaromatic compounds such as pyridine.
Designing of new cationic surfactant based micellar systems as drug carriers: an investigation into the drug cell membrane interactions
Published in Journal of Dispersion Science and Technology, 2019
Rabia Talat, Summaira Fayyaz, Saqib Ali, Nasir Khalid, Ali Haider, Afzal Shah, Faizan Ullah
Among the family of cationic surfactants, surface properties of 1-alkyl-4-alkyl pyridinium compounds have been widely studied. The pyridinium based surfactants have been known for their wide range of applications e.g. corrosion inhibition, textile processing, oil recovery, emulsion polymerization, use in cosmetics and mineral flotation. In particular, biological applications of pyridinium salts include their use as drugs, gene delivery agents, DNA extraction and antimicrobial properties.[14,15] Herein we report the synthesis and characterization of pyridinium based cationic surfactants and their potential biological as well as drug carrier applications.