The aqueous polymerization of acrylamide initiated by the potassium persulfate/lactic acid system catalyzed by Ag+ ions has been studied iodometrically over the temperature range from 35 to 50 ± 0.2°C. The rate of polymerization is governed by the expression Rp ∞ [M]0.8[K2S2O8]1.0[Ag]1.0 The deviation from normal kinetics has been studied. A tentative mechanism of initiation is suggested. The overall energy of activation is 5.52 kcal/mol. 相似文献
The use of ionic liquids with fluoride anion (IL‐F) is challenging because of side reactions. Neat 1‐allyl‐3‐methylimidazolium fluoride (AlMeImF) is used as a solvent in microwave‐assisted acylation of cellulose. The results are disappointing due to side reactions in the IL proper, and F–‐mediated hydrolysis of the produced ester. A dramatic improvement is observed, when AlMeImF/DMSO mixture is employed. The results are comparable to those obtained when pure 1‐allyl‐3‐methylimidazolium chloride is employed. FTIR spectroscopy shows that dissolving a carboxylic acid anhydride in IL‐F leads to the formation of acyl fluoride. Thus ILs are far from being “spectator” solvents. The new approach (use of IL‐F/DMSO) is attractive because of its efficiency, low cost, and applicability to the derivatization of any polymer.
Surface-mounted metal–organic frameworks (SURMOFs) show promising behavior for a manifold of applications. As MOF thin films are often unsuitable for conventional characterization techniques, understanding their advantageous properties over their bulk counterparts presents a great analytical challenge. In this work, we demonstrate that MOFs can be grown on calcium fluoride (CaF2) windows after proper functionalization. As CaF2 is optically (in the IR and UV/Vis range of the spectrum) transparent, this makes it possible to study SURMOFs using conventional spectroscopic tools typically used during catalysis or gas sorption. Hence, we have measured HKUST-1 during the adsorption of CO and NO. We show that no copper oxide impurities are observed and also confirm that SURMOFs grown by a layer-by-layer (LbL) approach possess Cu+ species in paddlewheel confirmation, but 1.9 times less than in bulk HKUST-1. The developed methodology paves the way for studying the interaction of any adsorbed gases with thin films, not limited to MOFs, low temperatures, or these specific probe molecules, pushing the boundaries of our current understanding of functional porous materials. 相似文献
The aim of present investigation was to prepare nanoparticles of chitosan and perform batch and column studies with them to study their defluoridation capacity. The nanoparticles of chitosan were characterized by techniques like FTIR, SEM, TEM, etc. Effect of initial fluoride concentration, adsorbent dose, pH and temperature were studied in the batch studies. Effect of bed height, flow rate, and inlet concentration on the column performance were studied. Performance of packed columns were described through the concept of breakthrough curves and column parameters were predicted as a function of bed heights. The breakthrough curves were defined by the Adams-Bohart and Wolborska models. 相似文献
Amines are prevalent in drugs, natural products, materials, catalysts etc.. The reaction of C=N in imines is one of the most important approaches to synthesize amines1. Sulfinyl group as an excellent chiral auxiliary and activator of the C=N bond for nucl… 相似文献
Imines, Im, such as MeN=C(Ph)H (5), 2-methyl 4,5-dihydrothiazole (8a), 2-methyl 4,5-dihydrooxazole (8b) and MeN=C(OMe)Me (13) add to the α-carbon atom of the vinylidene ligand in [(CO)5Cr=C=CMe2] (4) to give isolable zwitterionic adducts, [(CO)5Cr−–C(=CMe2)(Im+)]. The reaction of [(CO)5W=C=CPh2] (12) with 13 also yields an adduct, [(CO)5W−–C(=CPh2){NMe=C(OMe)Me}+] (15), whereas from the corresponding reaction of 4 with xanthylideneimine, H–N=C(C6H4)2O (16), a carbene complex, [(CO)5Cr=C(i-Pr)–N=C(C6H4)2O] (17), is obtained. Complex 17 presumably is formed by initial addition of 16 to 4 and subsequently rapid rearrangement. In solution, the adduct [(CO)5Cr−–C(=CMe2)(NMe=C(Ph)H)+] (6) slowly cyclizes to form the 2-azetidin-1-ylidene complex [(CO)5Cr=
Me2] (7). In contrast, when solution of those zwitterions are heated that are formed by addition of 4,5-dihydrothiazole or 4,5-dihydrooxazole to 4, no cyclization is observed but rather the formation of 4,5-dihydrothiazole and 4,5-dihydrooxazole complexes, respectively. The structures of two adducts, [(CO)5Cr−–C(=CMe2)(Im+)] (Im=MeN=C(Ph)H, 2-methyl 4,5-dihydrothiazole) and of the substitution product [(CO)5W(2-methyl 4,5-dihydrothiazole)] have been established by X-ray structural analyses. 相似文献