共查询到20条相似文献,搜索用时 15 毫秒
1.
研究了1-1型钠盐对五种非 离子表面活性剂水溶液雾点的影响,有九种钠盐使雾点下降,下降的依次是IO^-3>OH^->F^->CH3COO^->BrO^-3<>Cl^->Br^_>ClO3^-≥NO^-3;有三种钠盐使雾点升高,升高的效率依次是CNS^->ClO^->I^-。 相似文献
2.
This article deals with the cloud point studies of ethoxylated sorbitan ester, Tween in the presence of glycols, and salts. Cloud point temperature of Tween 20 (5 mol dm?3) and Tween 80 (1 mol dm?3) has been determined in the presence of various salts in addition to glycols. The glycols chosen for these studies were triethylene glycol (TEG), and ethylene glycol mono butylether (EGMBE). At concentration below 0.02 M these salts have no significant effect on cloud point temperature in all cases. The cloud point temperature of Tween+TEG and Tween+EGMBE found to decrease in the presence of sodium chloride (NaCl) and potassium chloride (KCl). The cloud point temperature of Tween 20 + TEG and Tween 20 + EGMBE found to increase in the presence of urea and nicotinamide. The change in cloud point was found to be more in case of nicotinamide as compare to urea. The influence of an additive on the cloud point depends on how it affects the intermicellar interactions. An effort has been made to understand the interaction between solvent and additives leading to a change in solubility of Tween. 相似文献
3.
Jiani Gong Kaixin Yao Qihan Sun Yujia Sun Lijie Sun Changyao Liu Bo Xu Jiajing Tan Li Zhao Baocai Xu 《Molecules (Basel, Switzerland)》2022,27(14)
In recent years, there has been increasing interest in daily-use chemical products providing a pleasant scent. The added fragrance molecules may induce microstructural transitions of surfactant aggregates, which further affect the physical and chemical properties of the products. Here, the effects of four types of aromatic alcohols (cinnamyl alcohol, phenyl ethanol, phenyl methanol and anisyl alcohol) on cetyltrimethylammonium bromide (CTAB)/KBr aggregates were studied. The combined results from rheology, dynamic light scattering, and transmission electron microscopy measurements showed that cinnamyl alcohol induced significant micellar growth, while increases in micellar growth were less obvious for the other aromatic alcohols. The changes in the interfacial molarities of water, aromatic alcohol, and bromide ions during such transitions were studied using the chemical trapping method. Transitions resulting from added cinnamyl alcohol were accompanied by significant declines in interfacial water and bromide ion molarities, and a rise in interfacial alcohol molarity. The marked decrease in interfacial water molarity was not observed in previous studies of the octanol induced formation of wormlike micelles and vesicles, indicating that a different mechanism was presented in the current system. Nuclear magnetic resonance investigation showed that π–π stacking between cinnamyl alcohols, but not cation–π interactions between alcohols and CTAB headgroups, facilitated the tight packing of alcohol molecules in CTAB aggregates and the repulsion of water from the interfacial region. The current study may provide a theoretical basis for the morphological regulation of surfactant aggregates in the presence of additives. 相似文献
4.
Marcos de A. Bezerra André L. B. Conceição Sérgio L. C. Ferreira 《Mikrochimica acta》2006,154(1-2):149-152
This paper describes the development of a cloud point extraction procedure for the determination of manganese in saline effluents
by flame atomic absorption spectrometry (FAAS). The optimization step was performed using the Doehlert matrix involving the
following variables: buffer concentration, pH and centrifugation time. The validation process was assessed as: parameters
of the analytical curve, precision, effect of other ions in the proposed procedure, robustness test and accuracy. The proposed
procedure allows the determination of manganese with a detection limit (3δ/S) of 0.60 μg L−1, and a precision expressed as relative standard deviation (RSD) of 2.2 (n = 8) and 1.5% (n = 8) for a manganese concentration
of 1 and 5 μg L−1, respectively. The pre-concentration factor obtained was 84. The recovery achieved for the determination of manganese in
the presence of several other metal ions demonstrated that this procedure could be satisfactorily applied to the analysis
of environmental samples. The accuracy was confirmed by the analysis of CRM trace elements in water (NIST 1643d). This procedure
was applied to the determination of manganese in saline effluents of a petroleum refinery. For three analyzed samples the
manganese content varied between 44.9 and 67.9 μg L−1. 相似文献
5.
A convenient and environmentally benign method for reducing the carbonyl group in hydroxy- and amino- 9,10-anthracenediones, ortho (or para) acyl phenols and acyl anilines to a methylene group by zinc powder in an aqueous sodium hydroxide solution was reported. Based on theoretical calculations using the density functional theory (DFT), the mechanism of these reduction reactions was postulated. This mechanism can be applied to help predicting the reduced products of aryl ketones (or aldehydes) in an alkaline solution. 相似文献
6.
Dr. Rosa María Tejedor Dr. Santiago Uriel Sara Graus Dr. Teresa Sierra Dr. José Luis Serrano Dr. Rosa M. Claramunt Dr. Concepción López Dr. Marta Pérez‐Torralba Dr. Ibon Alkorta Dr. José Elguero 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(19):6044-6051
Achiral compounds 4‐methoxy‐4‐(p‐methoxyphenyl)cyclohexanoneethylene ketal ( 2 ), 4‐hydroxy‐4‐(p‐methoxy phenyl)cyclohexanoneethylene ketal ( 3 ), and 3,5‐dimethyl‐4‐nitropyrazole ( 4 ) crystallized in chiral structures and the samples showed an enantiomeric excess. We have determined the absolute structures of these compounds by using X‐ray diffraction with copper radiation at low temperatures. Moreover, we have also established the prevalent absolute structures in these samples, by comparing their calculated and solid‐state vibrational circular dichroism (VCD) spectra. The consistency of this method was confirmed by using (R,R)‐2,8‐diiodo‐4,10‐dimethyl‐6 H,12H‐5,11‐methano‐dibenzo[b,f][1,5]diazocine, Tröger′s base, (R,R)‐ 1 , as a chiral compound of known absolute configuration. 相似文献
7.
An efficient, facile, and rapid oxidation of alcohols to the corresponding aldehydes or ketones with a stoichiometric amount of iodosobenzene (PhIO) in the presence of catalytic amounts of 2,2,6,6-tetramethyl-1-piperidinyloxyl free radical (TEMPO), KBr, and a surfactant, such as SDS (sodium dodecylsulfate), was reported. The oxidation proceeded in water at room temperature to afford aldehydes or ketones in excellent yields and high selectivity without overoxidation to carboxylic acids. Selective oxidation of primary alcohols in the presence of secondary alcohols was also achieved with the catalytic system of PhIO/TEMPO/KBr/SDS. A possible mechanism for the oxidation was supposed. 相似文献
8.
Barahman Movassagh Amir Mossadegh 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2275-2278
Abstract A convenient method for the synthesis of alkyl aryl- and diaryl sulfides by the reaction of diphenyliodonium iodide and disulfides in the presence of Zn/AlCl 3 system in acetonitrile is reported. 相似文献
9.
10.
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.
11.
GOUDARZIAFSHAR Hamid GHORBANI-CHOGHAMARANI Arash NIKOORAZM Mohsen NASERIFAR Zahra 《中国化学》2009,27(9):1801-1804
Highly efficient selective oxidation of sulfides to sulfoxides by NaNO2 and silica sulfuric acid catalyzed with KBr or NaBr has been reported. This oxidation was carried out in the presence of wet SiO2 (50% w/w) in acetonitrile at room temperature with good to excellent yields. 相似文献
12.
Neslihan Saki Burcak Icli Orkun Cevheroglu Engin U. Akkaya 《Journal of inclusion phenomena and macrocyclic chemistry》2006,55(3-4):219-222
In an attempted synthesis of peripherally pyridine-substituted cucurbituril, an unexpected cyclized product was obtained. A careful NMR analysis followed by mass spectrometry and preliminary crystallographic analyses, helped us in resolving the structure. The structure has two quaternized pyridine functionalities and a groove suitable as a potential receptor site. In addition, just like the parent glycoluril structure, two remaining urea-derived nitrogens can be alkylated by alkyl halides. Thus, we believe this high yielding reaction may become an entry point to a new class of anion receptors. 相似文献
13.
Ali Fouad Adel A. Marzouk Montaser Sh. A. Shaykoon Samy M. Ibrahim Sobhy M. El-Adl Ashraf Ghanem 《Molecules (Basel, Switzerland)》2021,26(12)
Daptomycin, a macrocyclic antibiotic, is here used as a new chiral selector in preparation of chiral stationary phase (CSP) in a recently prepared polymer monolithic capillary. The latter is prepared using the copolymerization of the monomers glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EGDMA) in the presence of daptomycin in water. Under reversed phase conditions (RP), the prepared capillaries were tested for the enantioselective nanoliquid chromatographic separation of fifty of the racemic drugs of different pharmacological groups, such as adrenergic blockers, H1-blockers, NSAIDs, antifungal drugs, and others. Baseline separation was attained for many drugs under RP-HPLC. Daptomycin expands the horizon of chiral selectors in HPLC. 相似文献
14.
15.
Reaction of 3‐Hydroxyquinoline‐2,4‐diones with Inorganic Thiocyanates in the Presence of Ammonium or Alkylammonium Ions: the Unexpected Replacement of a Hydroxy Group by an Amino Group 下载免费PDF全文
Antonín Klásek Ondřej Rudolf Michal Rouchal Antonín Lyčka 《Helvetica chimica acta》2015,98(3):318-335
3‐Hydroxyquinoline‐2,4‐diones react with KSCN in the presence of the NH$\rm{{_{4}^{+}}}$ ions to generate 2,3‐dihydro‐3‐thioxoimidazo[1,5‐c]quinazolin‐5(6H)‐ones, 2,3‐dihydro‐2‐thioxo‐1H‐imidazo[4,5‐c]quinolin‐4(5H)‐ones, and products of molecular rearrangement of the 3‐aminoquinolinedione intermediates. Starting compounds with a benzyl (Bn) group at C(3) afford 3‐aminoquinolinediones, even when only AcONH4 is used. The results of the reaction between 3‐hydroxyquinoline‐2,4‐diones and KSCN in the presence of BuNH2 show that replacing a OH group with a secondary NH2 group is also possible. 相似文献
16.
Titania sol‐gel modified gold electrode (TSGMGE) was prepared with the usage of a new proposed cold deposition method at ?10 °C. Scanning electron microscope (SEM) operating at 30 kV was used to obtain micrographs of unmodified and modified electrodes. The obtained results showed that this procedure yields a sol‐gel with high porosity in comparison to conventional methods. The modified Au electrode was fabricated by trapping the L‐glutamine in titania sol‐gel at low temperatures to preparation of a new titania sol‐gel glutamine modified gold electrode (TSGGMGE). The possibility determination of traces of Cu(II) in the presence of As(III) was investigated using proposed electrode. Under the optimized conditions, copper was accumulated at ?0.35 V (vs. Ag/AgCl) for 40 s in 0.1 M acetate buffer (pH 4.0) in the presence of different amounts of arsenic. Two dynamic linear responses with good reproducibility were observed for copper ions in the concentration range of 1 × 10?6 ?4 × 10?4 M and 4 × 10?8 ?6 × 10?7 M. 相似文献
17.
Ali Ramazani Aram Rezaei Amir Tofangchi Mahyari Morteza Rouhani Mehdi Khoobi 《Helvetica chimica acta》2010,93(10):2033-2036
The zwitterion, formed from the reaction of an alkyl isocyanide and a dialkyl acetylenedicarboxylate, reacts with phenacyl halides in H2O to produce γ‐iminolactone derivatives in high yields. H2O helps to avoid the use of highly toxic and environmentally unfavorable solvents for this conversion. 相似文献
18.
《Journal of Chemical Sciences》1994,106(2):183-193
The principle of hard and soft acids and bases is interpreted as the result of two opposing tendencies, one related to the
charge transfer process (chemical potential equalization principle), and the other one related to the reshuffling of the electronic
density (maximum hardness or minimum softness principle). A local version of the principle is elucidated by assuming that
these tendencies are dominated by the local properties rather than by the global properties of the molecule. This principle
is used together with the Fukui function of the atoms in the molecule to characterize the reactive sites. The results presented
for the nucleophilic addition to the pyridinium ion, and for the electrophilic substitution on pyridine oxide show the usefulness
of these concepts in describing the inherent reactivity of chemical species. 相似文献
19.
Inside Back Cover: NMR Diffusion Measurements as a Simple Method to Examine Solvent–Solvent and Solvent–Solute Interactions in Mixtures of the Ionic Liquid [Bmim][N(SO2CF3)2] and Acetonitrile (ChemPhysChem 23/2016) 下载免费PDF全文
Dr. Sinead T. Keaveney Karin S. Schaffarczyk McHale Dr. James W. Stranger Dr. Batchimeg Ganbold Prof. William S. Price Prof. Jason B. Harper 《Chemphyschem》2016,17(23):4028-4028
20.
Erwin G. Abucayon Rahul L. Khade Douglas R. Powell Yong Zhang George B. Richter‐Addo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(51):18771-18776
Some bacterial heme proteins catalyze the coupling of two NO molecules to generate N2O. We previously reported that a heme Fe–NO model engages in this N?N bond‐forming reaction with NO. We now demonstrate that (OEP)CoII(NO) similarly reacts with 1 equiv of NO in the presence of the Lewis acids BX3 (X=F, C6F5) to generate N2O. DFT calculations support retention of the CoII oxidation state for the experimentally observed adduct (OEP)CoII(NO?BF3), the presumed hyponitrite intermediate (P.+)CoII(ONNO?BF3), and the porphyrin π‐radical cation by‐product of this reaction, and that the π‐radical cation formation likely occurs at the hyponitrite stage. In contrast, the Fe analogue undergoes a ferrous‐to‐ferric oxidation state conversion during this reaction. Our work shows that cobalt hemes are chemically competent to engage in the NO‐to‐N2O conversion reaction. 相似文献