Reinforcing effect of Lewis acid–base interaction on the high-temperature colloidal stability and tribological performance of lubricating grease

Nan Xu,Wei-Min Liu,Ming Zhang,Xiaobo Wang 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.46 No.-

The high-temperature tribological performance of lithium grease is enhanced by addition of Lewis acidborate ester, which could interact with Lewis base RCO2of lithium 12-hydroxystearate (LHS, constitutethe thickenerfiber network of lithium grease) to form a Lewis acid–base complex. Important detailsabout the Lewis acid–base complex and its reinforcing effect on the tribological performance areelucidated by means of SRV oscillating friction and wear tester (SRV), Fourier transformation infraredspectroscopy (FTIR), TGA–DSC, and rheological methods. The experimental results strongly suggest thatthere is a Lewis base–acid interaction between the boron atom of borate ester or boric acid and theoxygen atom of RCO2. Lewis acid centers can serve as second-level linking points to reinforce thestrength of the thickenerfiber network and further improve the colloidal stability of lubricating grease. Compared with pure LHS, the Lewis acid–base complex displays higher thermal stability, allowinglithium grease to be applied to higher temperature. Because of the enhancement of thermal stability andcolloidal stability,film-forming property under high temperature can be greatly improved, resulting in>15% friction and >95% wear reductions.

Designed Synthesis of Mesoporous Solid-Supported Lewis Acid-Base Pairs and Their CO₂ Adsorption Behaviors

Zakharova, Maria V.,Masoumifard, Nima,Hu, Yimu,Han, Jongho,Kleitz, Freddy,Fontaine, Fré,dé,ric-Georges American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.15

<P>Conventional amines and phosphines, such as diethylenetriamine, diphenylpropylphosphine, triethylamine, and tetramethylpiperidine, were grafted or impregnated on the surface of metalated SBA-15 materials, such as <B>Ti</B>-, <B>Al</B>-, and <B>Zr</B>-SBA-15, to generate air-stable solid-supported Lewis acid-base pairs. The Lewis acidity of the metalated materials before and after the introduction of Lewis bases was verified by means of pyridine adsorption-Fourier transform infrared spectroscopy. Detailed characterization of the materials was achieved by solid-state <SUP>13</SUP>C and <SUP>31</SUP>P MAS NMR spectroscopy, low-temperature N<SUB>2</SUB> physisorption, X-ray photoelectron spectroscopy, and energy-dispersive X-ray mapping analyses. Study of their potential interactions with CO<SUB>2</SUB> was performed using CO<SUB>2</SUB> adsorption isotherm experiments, which provided new insights into their applicability as solid CO<SUB>2</SUB> adsorbents. A correlation between solid-supported Lewis acid-base pair strength and the resulting affinity to CO<SUB>2</SUB> is discussed based on the calculation of isosteric enthalpy of adsorption.</P> [FIG OMISSION]</BR>

Adipic Acid와 Diethylene Glycol의 Polyesterification에 대한 유기나노점토와 촉매의 영향

박경규 ( Kyung Kyu Park ),신승욱 ( Sung Wook Shin ),오민지 ( Min Ji Oh ),이상호 ( Sang Ho Lee ) 한국고무학회 2011 엘라스토머 및 콤포지트 Vol.46 No.1

Adipic acid(AA)와 diethylene glycol(DEG) 사이에서 일어나는 반응의 속도에 대한 유기나노점토(Cloisite 30B)의 영향을 규명하기 위하여 383K와 423 K에서 Brønsted acid인 p-toluene sulfonic acid( p-TSA)와 Lewis acid인 butylchlorotin dihydroxide를 촉매로 사용하여 에스테르 반응을 수행하였다. 촉매의 양은 전체반응물의 0.14mol%만큼 사용하였다. 반응 · 생성물의 산가로부터 계산된 전환율 vs. 시간의 자료를 사용하여 반응속도를 해석하였다. [OH]/[COOH] 초기 몰비가 2인 상태에서 수행되는 polyester-diol 합성반응의 속도는 p-TSA 촉매하에서는 AA에 대하여 2차 반응으로, butylchlorotin dihydroxide 촉매하에서는 AA에 대하여 1차 반응으로 잘 해석되었으며 두 반응의 활성화 에너지는 각각 42.2 kJ/mol, 63.8 kJ/mol이었다. AA와 DEG에 Cloisite 30B를 5 wt% 첨가시키면 p-TSA 촉매는 활성이 크게 줄어 반응속도가 매우 느려졌으며, 이 때 활성화 에너지는 72.9 kJ/mol로 높게 계산되었다. Butylchlorotin dihydroxide 촉매는 Cloisite 30B의 첨가에 관계없이 거의 일정한 활성을 유지하였다. Butylchlorotin dihydroxide 촉매하에서 Cloisite 30B를 첨가한 반응의 활성화 에너지는 61.8 kJ/mol로 Cloisite 30B를 첨가하지 않은 반응의 활성화 에너지보다 약간 낮았다. Effect of organo nanoclay (Cloisite 30B) on the polyesterification of adipic acid (AA) with diethylene glycol (DEG) was investigated with p-toluene sulfonic acid (p-TSA) (Brønsted acid) and butylchlorotin dihydroxide (Lewis acid) catalyst at 383 and 423 K. The initial [OH]/[COOH] molar ratio was two and the concentration of the catalysts in the reactants was 0.14 mol% based on the total reactants. The kinetics of the polyesterification was interpreted with the conversion data that was calculated from the acid values of the reactant-product mixture. The reaction rate of the polyesterification, which was catalyzed with p-TSA, exhibited the second-order dependency on AA concentration. When Butylchlorotin dihydroxide was used, the reaction rate revealed the first-order dependency on AA concentration. The activation energy of the reactions catalyzed with p-TSA and Butylchlorotin dihydroxide were calculated at 42.2 and 63.8 kJ/mol, respectively. Addition of 5 wt% Cloisite 30B to the reactant significantly diminished the activity of p-TSA, so the reaction rate decreased and the activation energy was calculated at 72.9 kJ/mol. Butylchlorotin dihydroxide catalyst maintained its activity regardless of the addition of Cloisite 30B to the reactant and the activation energy was calculated to 61.8 kJ/mol. Lewis acid catalyst, butylchlorotin dihydroxide, was more effective than Brønsted acid catalyst for the esterification of AA with DEG.

Theoretical Studies for the Supercritical CO2 Solubility of Organophosphorous Molecules: Lewis Acid-Base Interactions and C?H…O Weak Hydrogen Bonding

Kyung Hyun Kim,Yongho Kim* 대한화학회 2007 Bulletin of the Korean Chemical Society Vol.28 No.12

Exploring the basic concepts for the design of CO2-philic molecules is important due to the possibility for green chemistry in supercritical CO2 as substitute solvent systems. The Lewis acid-base interactions and CH…O weak hydrogen bonding were suggested as two key factors for the solubility of CO2-philic molecules. We have performed high level quantum mechanical calculations for the van der Waals complexes of CO2 with trimethylphosphate and trimethylphosphine oxide, which have long been used for metal extractants in supercritical CO2 fluid. Structures and energies were calculated using the MP2/6-31+G(d) and recently developed multilevel methods. These studies indicate that the Lewis acid-base interactions have larger impact on the stability of structure than the CH갤O weak hydrogen bonding. The weak hydrogen bonds in trimethylphosphine oxide have an important role to the large supercritical CO2 solubility when a metal is bound to the oxygen atom of the P=O group. Trimethylphosphate has many Lewis acid-base interaction sites so that it can be dissolved into supercritical CO2 easily even when it has metal ion on the oxygen atom of the P=O group, which is indispensable for a good extractant.

Revisiting hydrogen spillover in Pt/LTA: Effects of physical diluents having different acid site distributions

Lee, Songhyun,Lee, Kyungho,Im, Juhwan,Kim, Hyungjun,Choi, Minkee Elsevier 2015 Journal of catalysis Vol.325 No.-

<P><B>Abstract</B></P> <P>Historically, Pt/LTA (<I>e.g</I>., Pt/NaA) has often been used as a model catalyst for studying the catalytic functions of hydrogen spillover (H spillover). Notably, none of the works reported appreciable catalytic activities for Pt/LTA alone, while markedly enhanced activities were reported after physical dilution with some acidic oxides. It was often speculated without experimental evidence that activated hydrogen generated from Pt/LTA can migrate to the diluents surface (“inter-particular” H spillover) where organic reactants can react with spilt-over hydrogen. In this work, we carefully studied benzene hydrogenation activities of Pt/NaA and its decationized form (Pt/HA), before and after the physical dilution with various metal oxides possessing different Lewis and Brønsted acidity. The originally negligible activity of Pt/NaA increased significantly after mixing with various acidic oxides. The physical dilutions, however, resulted in a significant alteration of Pt/NaA structure due to solid-state H<SUP>+</SUP> exchange, which made the catalytic interpretation vague. In contrast, Pt/HA structure did not change after the dilutions, and thus could be used as an ideal catalytic model system for studying inter-particular H spillover. The catalytic results showed that Al-rich metal oxides with abundant Lewis acid sites are effective for enhancing the catalytic activity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Catalytic effects of physically diluting Pt/NaA and Pt/HA with various acidic metal oxides were studied. </LI> <LI> Physical dilution altered the original structure of Pt/NaA due to solid-state H<SUP>+</SUP>-exchange. </LI> <LI> Physical dilution did not change the structure of decationized form of Pt/NaA (Pt/HA). </LI> <LI> Dilution with Al-rich metal oxides can markedly enhance the catalytic activity of Pt/HA. </LI> <LI> Lewis acid sites may play a significant role in the catalytic use of hydrogen spillover. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Determination of surface properties and Gutmann’s Lewis acidity–basicity parameters of thiourea and melamine polymerized graphitic carbon nitride sheets by inverse gas chromatography

Sreekanth, T.V.M.,Basivi, Praveen Kumar,Nagajyothi, P.C.,Dillip, G.R.,Shim, J.,Ko, T.J.,Yoo, K. Elsevier 2018 Journal of chromatography Vol.1580 No.-

<P><B>Abstract</B></P> <P>Melamine and thiourea-derived graphitic carbon nitrides (M-GCN/T-GCN) were synthesized and characterized. The surface properties were investigated using inverse gas chromatography (IGC) and compared. Net retention volumes of M-GCN and T-GCN were measured with <I>n</I>-alkanes (C<SUB>5</SUB>–C<SUB>10</SUB>) and polar probes. The London dispersive surface free energies ( γ s d ), calculated using Schultz and Dorris–Gray methods, decreased linearly with increasing temperature. The specific components of the enthalpy and entropy of adsorption for the polar probes were obtained using the Schultz, Dong, and Sawyer–Brookman methods. The Gutmann’s Lewis acid–base parameters, <I>K<SUB>a</SUB> </I> and <I>K<SUB>b</SUB> </I>, were determined using the surface free energy ( Δ G a S ) via these methods. The surface character ‘<I>S’</I> values (<I>K<SUB>b</SUB> </I>/<I>K<SUB>a</SUB> </I>) of M-GCN and T-GCN using the respective methods are 4.04, 3.78, and 5.08 and 4.11, 5.27, and 2.86. Hence, the surfaces contain more basic than acidic sites and could interact strongly with acidic media. Thus, IGC elucidates the surface charges of the GCN matrix resulting from surface chemical modification.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Graphitic carbon nitride was synthesized using two precursors, melamine and thiourea. </LI> <LI> Physicochemical properties were confirmed by XRD, XPS and BET. </LI> <LI> Inverse gas chromatography was employed to understand surface free energy of GCN. </LI> <LI> The London dispersive parameters were determined by Schultz/Dorris–Gray methods. </LI> <LI> The Lewis acid–base parameters, showing the more basic character of GCN. </LI> </UL> </P>

Dual-end-functionalized tin (Sn)-phyllosilicates for the esterification of oleic acid

Nam, B.,Lee, H.U.,Park, S.Y.,Son, B.C.,Lee, G.W.,Park, J.Y.,Lee, Y.C. Korean Society of Industrial and Engineering Chemi 2016 Journal of industrial and engineering chemistry Vol.41 No.-

<P>We designed dual-end-functionalized tin (Sn)-phyllosilicate, where the -SH functional groups were subsequently oxidized for -SO3H/SO4H functionalities in a Bronsted acid with/without NH2 functional groups in a Bronsted base. Dual-end-functionalized tin (Sn)-phyllosilicates [MTES:APTS = 1.0:0.11, MTES:TEOS = 1.0:0.11 and 1.0:0.43, v/v] were fabricated where the inorganic framework of Sn species can function as a Lewis acid. The Sn-phyllosilicates with dual acids were applied to esterify oleic acid and produce oleic acid-methyl-ester to test their feasibility as fatty-acid-conversion solid catalysts. In the absence of amine groups, the increase in ratio of tetraethyl orthosilicate (TEOS) to (3-mercaptopropyl)-trimethoxysilane (MTES) for the synthesis of Sn-phyllosilicates (MTES:TEOS = 1.0:0.11 and 1.0:0.43, v/v) increased the recovery of Sn-phyllosilicate in the solvent media and gradually decreased the oleic acid methyl-ester production efficiency (%) of the oleic acid conversion. At the fixed 2.0 wt% Sn-phyllosilicate (MTES:APTS = 1.0:0.11, v/v) loading and oleic acid:MeOH weight ratio = 1:1, an 80 degrees C reaction temperature and 4 h reaction time were determined to be the optimal conditions for the oleic acid methyl-ester production, which had 90% oleic acid conversion efficiency. When the Sn-phyllosilicate (MTES:APTS = 1.0:0.11, v/v) loading was increased from 0.1 to 5.0 wt% at 80 degrees C and 4 h, the fatty-acid conversion efficiency (%) of oleic acid gradually increased from 39.16 to 92.23%. In contrast, Sn-phyllosilicate (MTES:TEOS = 1.0:0.43) had the lowest oleic acid conversion efficiency (%) but the highest catalyst recovery. In summary, this study presents a facile method to produce oleic acid conversion catalysts on an industrial scale. (C) 2016 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.</P>

Dual-end-functionalized tin (Sn)-phyllosilicates for the esterification of oleic acid

남보라,이현욱,박소영,손병철,이고운,박지연,이영철 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.41 No.-

We designed dual-end-functionalized tin (Sn)-phyllosilicate, where the –SH functional groups weresubsequently oxidized for –SO3H/SO4H functionalities in a Brønsted acid with/without NH2 functionalgroups in a Brønsted base. Dual-end-functionalized tin (Sn)-phyllosilicates [MTES:APTS = 1.0:0.11,MTES:TEOS = 1.0:0.11 and 1.0:0.43, v/v] were fabricated where the inorganic framework of Sn speciescan function as a Lewis acid. The Sn-phyllosilicates with dual acids were applied to esterify oleic acid andproduce oleic acid-methyl-ester to test their feasibility as fatty-acid-conversion solid catalysts. In theabsence of amine groups, the increase in ratio of tetraethyl orthosilicate (TEOS) to (3-mercaptopropyl)-trimethoxysilane (MTES) for the synthesis of Sn-phyllosilicates (MTES:TEOS = 1.0:0.11 and 1.0:0.43, v/v)increased the recovery of Sn-phyllosilicate in the solvent media and gradually decreased the oleic acidmethyl-ester production efficiency (%) of the oleic acid conversion. At the fixed 2.0 wt% Sn-phyllosilicate(MTES:APTS = 1.0:0.11, v/v) loading and oleic acid:MeOH weight ratio = 1:1, an 80 8C reactiontemperature and 4 h reaction time were determined to be the optimal conditions for the oleic acidmethyl-ester production, which had 90% oleic acid conversion efficiency. When the Sn-phyllosilicate(MTES:APTS = 1.0:0.11, v/v) loading was increased from 0.1 to 5.0 wt% at 80 8C and 4 h, the fatty-acidconversion efficiency (%) of oleic acid gradually increased from 39.16 to 92.23%. In contrast, Snphyllosilicate(MTES:TEOS = 1.0:0.43) had the lowest oleic acid conversion efficiency (%) but the highestcatalyst recovery. In summary, this study presents a facile method to produce oleic acid conversioncatalysts on an industrial scale.

보레인 화합물을 이용한 불소 이온 검출에 관한 교육 연구

이강문(Kang Mun Lee) 충북대학교 교육개발연구소 2016 敎育硏究論叢 Vol.37 No.1

본 연구는 다양한 치환기를 포함하고 있는 3종의 보레인 화합물을 합성하고, UV/Vis 하에서 합성된 화합물이 내는 흡광을 이용하여 유기 용매 하에서 매우 적은 농도로 존재하는 불소 이온(F-)의 검출에 적용하고자 하는 것이다. We propose a research for detection of the fluoride ion using borane compounds. Based on the Lewis acid-base reaction, we discussed the fundamental of sensing for fluoride ion. One of the important aspects in the chemistry of organoboranes is their behaviors as Lewis acids, which is a result of the vacant 2pπ orbital on the tricoordinate boron center. The electronic interaction between boron atoms and π-orbitals of donor molecules, constructed from the carbon 2p orbitals, is generally strong. Boron atoms can reach the desired octet configuration either through π-overlap with a suitable X or through formation of Lewis acid-Lewis base complexes.

Lewis Acid-Catalyzed Reactions of Anthrone: Preference for Cycloaddition Reaction over Conjugate Addition Depending on the Functionality of α,β-Unsaturated Carbonyl Compounds

Baik, Woon-Phil,Yoon, Cheol-Hoon,Koo, Sang-Ho,Kim, Ha-Kwon,Kim, Ji-Han,Kim, Jeong-Ryul,Hong, Soo-Dong Korean Chemical Society 2004 Bulletin of the Korean Chemical Society Vol.25 No.4

The Lewis acid-catalyzed reactions of anthrone with a variety of ethylenic substrates under various conditions have been studied. It has been observed that depending on kinds of ethylenic substrates and catalysts, products were varied. In particular, the $ZnCl_2$-catalyzed reaction of anthrone with ${\alpha},{\beta}$ -unsaturated ester gave bridged compounds 3 (Diels-Alder adduct type) and mono-Michael adduct 4 exclusively, while the base-catalyzed reaction gave 10,10-bis-Michael adduct as a major product independent of the amount of ethylenic substrate and base. Bridged compounds 3 were easily converted to the corresponding mono-Michael adduct 4 by a catalytic amount of base. Further Michael reaction of mono-Michael adducts with different ethylenic substrates in the presence of a catalytic amount of alkoxide gave unsymmetrical 10,10-bis Michael adducts in good or moderate yields.