Infrared spectroscopic studies of adsorption and catalysis. Part 3. Carboxylic acids and their derivatives adsorbed on silica

1969 ◽  
Vol 47 (12) ◽  
pp. 2237-2247 ◽  
Author(s):  
R. P. Young
Keyword(s):  
Acetic Acid ◽  
Room Temperature ◽  
Acetyl Chloride ◽  
Physical Adsorption ◽  
Spectroscopic Studies ◽  
Esterification Reaction ◽  
Oh Groups ◽  
Silica Surfaces ◽  
Propionyl Chloride ◽  
Hydrogen Bonded

Infrared spectra in the region 4000–1300 cm−1 have been obtained of acetic acid, acetyl chloride, acetic anhydride, propionic acid, and propionyl chloride adsorbed on discs of pressed silica powder. In all cases the spectra showed the presence of both the simple hydrogen-bonded species[Formula: see text]where X = OH, Cl, or O.CO.R and Si* represents a surface silicon atom, and also chemisorbed surface ester groups R.CO.O—Si*. The latter were characterized by a νC=O frequency in the 1760–1740 cm−1 region, whereas in the case of hydrogen-bonded physical adsorption, the νC=O frequency was about 20–30 cm−1 lower than that of the same molecule in the vapor phase. At high temperatures (150–200 °C) the water or hydrogen chloride eliminated in the surface esterification reaction was desorbed, and high conversions of surface OH to surface ester groups were observed. Under these conditions the carboxylic acid was formed from both the chloride and the anhydride; the latter was also produced at room temperature from the acid chloride. A scheme is suggested for the equilibration of these compounds on hydroxylated silica surfaces. The chemisorbed ester groups were susceptible to hydrolysis by water vapor, thus regenerating the original silanol OH groups.

Two Hydroxo Bridged Dinuclear Lanthanide Phen Complexes: [Ln2(phen)4(H2O)4(OH)2](phen)2(NO3)4 with Ln = Tm, Yb

2002 ◽  
Vol 57 (6) ◽  
pp. 625-630 ◽  
Author(s):  
Dan-Yi Wei ◽  
Yue-Qing Zheng ◽  
Jian-Li Lin
Keyword(s):  
Magnetic Moment ◽  
Room Temperature ◽  
Complex Cation ◽  
Magnetic Ordering ◽  
Oh Groups ◽  
Π Stacking ◽  
Lanthanide Atoms ◽  
Phenanthroline Monohydrate ◽  
Experimental Magnetic Moment ◽  
Hydrogen Bonded

AbstractTwo isostructural hydroxo bridged dinuclear lanthanide phen complexes of general composition [Ln2(phen)4(H2O)4(OH)2](phen)2(NO3)4 with Ln = Tm (1), Yb (2) were prepared by reactions of the corresponding lanthanide nitrate and phenanthroline monohydrate in CH3OH/H2O at pH = 5.5. They crystallize in the triclinic space group P1̄ (no. 2) with the cell dimensions: a = 11.233(1), b = 11.456(1), c = 14.011(2) Å , α = 93.91(1)°, β = 98.20(1)°, γ = 108.21(1)°, V = 1683.0(3)Å3, Z = 1 for 1 and a = 11.236(1), b = 11.480(2), c = 13.986(2)Å , α = 93.91(1)°, β = 98.17(1)°, γ = 108.33(1)°, V = 1682.9(3) Å3, Z = 1 for 2. The crystal structures are composed of the hydroxo bridged dinuclear [Ln2(phen)4(H2O)4(OH)4]4+ complex cations, hydrogen bonded NO3- anions and π-π stacking (phen)2 dimers. The lanthanide atoms are each surrounded by two phen ligands, two H2O molecules and two μ-OH groups to complete a tetragonal antiprismatic LnN4O4 coordination. Via two common μ-OH groups, two neighboring tetragonal antiprisms are condensed to form a centrosymmetric dinuclear [Ln2(phen)4(H2O)4(OH)4]4+ complex cation. The complex cations and (phen)2 dimers are assembled via π-π stacking interactions and hydrogen bondings into 2D layers parallel to (101̄), between which the hydrogen bonded NO3- anions are sandwiched. The Tm compound shows paramagnetic behavior with an experimental magnetic moment of 7.51 μB at room temperature. No magnetic ordering is evident down to 5 K. Over the temperature range 70 - 300 K, the Yb compound obeys the Curie-Weiss law with an experimental magnetic moment of 4.32 μB at room temperature and shows weak ferrimagnetic behavior at low temperature.

Solutions of phenyliodoso acetate. Decomposition in acetic acid and the effect of perchloric acid

1971 ◽  
Vol 24 (11) ◽  
pp. 2281 ◽  
Author(s):  
WD Johnson ◽  
JE Sherwood
Keyword(s):  
Acetic Acid ◽  
Perchloric Acid ◽  
Room Temperature ◽  
Spectroscopic Studies ◽  
Small Degree ◽  
Order Reaction ◽  
Zero Order ◽  
Hydrogen Ions ◽  
Ionic Dissociation ◽  
Zero Order Reaction

Phenyliodoso acetate appears capable of sustaining both free-radical and ionic reactions. Conductivity studies on solutions of phenyliodoso acetate in acetic acid indicate a small degree of ionic dissociation at temperatures above room temperature. Photolysis of the iodoso compound is a zero-order reaction and a homolytic mechanism is proposed for the decomposition. Evidence from conductivity and spectroscopic studies indicates that there is interaction between the iodoso compound and hydrogen ions. The decomposition of phenyliodoso acetate in acetic acid is markedly accelerated by the addition of perchloric acid. In the absence of acid no conclusion about mechanism is possible; when acid is present decomposition occurs by an ionic mechanism.

scholarly journals Regularities of Adsorption of Α-Oxypropionic Acid By Natural Zeolite

2021 ◽  
Vol 21 (1) ◽  
pp. 43-56
Author(s):  
V. Sabadash ◽  
J. Gumnitsky ◽  
O. Lyuta ◽  
A. Hyvlyud
Keyword(s):  
Wastewater Treatment ◽  
Natural Zeolite ◽  
Physical Adsorption ◽  
Experimental Studies ◽  
Sorption Process ◽  
Spectroscopic Studies ◽  
Sorption Properties ◽  
Electron Microscopic ◽  
Natural Sorbent ◽  
Oh Groups

Abstract Wastewaters from dairy processing factories contaminated with α-oxypropionic acid were monitored. Theoretical analysis of industrial wastewater treatment methods on zeolites of Sokyrnytsia deposit was carried out. The process of sorption of α-oxypropionic (α-oxypropionic) acid by natural zeolite of Sokyrnytsia deposit was considered. It was established that the most economically advantageous and safe is the method of adsorption using a natural sorbent - zeolite, which provides the lowest concentration of contaminants in treated wastewaters from dairies. An assessment of their number, localization features and measures of toxicological impact on the environment was done. The existing theoretical apparatus of description of adsorption processes was analyzed. The sorption properties of natural zeolite (clinoptilolite of Sokyrnytsia deposit) and activated carbon to α-oxypropionic acid were tested. Equilibrium values of adsorption capacity were calculated and corresponding isotherms at a temperature of 20 ° С were constructed. The porosity of the sorbent and its influence on the sorption properties were studied by the methods of physicochemical analysis. Infrared spectroscopic and electron microscopic studies confirmed the presence of the process of sorption by the surface of the internal pores of the zeolite of α-oxypropionic acid molecules. Experimental studies have confirmed the possibility of using natural zeolite for wastewater treatment of dairy factories. It was experimentally confirmed by physicochemical methods of analysis (electron microscopy, IR spectroscopy, microprobe analysis, mercury porometry) and was established that the process takes place both by the mechanism of ion exchange and physical adsorption. The content of carbon radicals in the zeolite matrix after the sorption process was confirmed by X-ray spectral microanalysis. The ability of zeolite to adsorb organic carboxylic acid radicals was confirmed by the results of IR spectroscopic studies. On the IR spectra there are strips of deformation and valence oscillations of the groups of the crystal lattice of the zeolite Si-O, Si-O-SiOH: 452, 990–1210, 1638, 3368 cm−1. The oscillation spectra of free OH groups in the region of 2600 cm−1 were revealed.

scholarly journals Hard porous chromium containing macrospheres as new catalysts for the esterification reaction of acetic acid with epichlorohydrin

2014 ◽  
Vol 12 (4) ◽  
pp. 528-536 ◽  
Author(s):  
Emil Muresan ◽  
Mioara Drobota ◽  
Alexandra Bargan ◽  
Corina Dumitriu
Keyword(s):  
Acetic Acid ◽  
Water Sorption ◽  
Room Temperature ◽  
Reaction Rate ◽  
Silica Matrix ◽  
Esterification Reaction ◽  
Metallic Ions ◽  
Marked Influence ◽  
Silicon Source ◽  
Edx Analyses

AbstractThis paper reports a systematic study on the preparation, characterization and testing of metallosilicate macrobeads that contain chromium ions as active catalytic centers. In order to obtain hard macrospheres, four metals (Cr, Al, Zr and Zn) were incorporated into the silica matrix using chitosan as a template and shape generator. Metallosilicate macrospheres were synthesized at room temperature using tetraethylorthosilicate as silicon source and chlorohydric acid as catalyst. The size of metallosilicate macrospheres was in the range 0.9 — 1.1 mm. The catalyst was characterised by means of water sorption technique, FTIR spectroscopy and SEM/EDX analyses. FTIR spectra put into evidence the presence of metallic ions within the silica framework. EDX analyses confirmed the efficient incorporation of metals within the silica matrix (the content of metals from the calcined catalyst is almost the same as that from the initial gel mixture). Porous structure of catalyst investigated by water sorption technique and by pycnometric methods (with n-heptan and mercury respectively) proved that the synthesized catalyst had micro, meso and macropores. Catalyst was tested in the esterification reaction of acetic acid with epichlorohydrin. The temperature and the amount of catalyst exerted a marked influence on reaction rate. This work opens new perspectives for heterogeneous catalysis encouraging the replacement of powder catalysts with macrospherical catalysts that are easy to recover and to reuse.

SPECTROSCOPIC STUDIES OF ALCOHOLS: IV. CONFORMATIONAL HETEROGENEITY OF 1-PROPANOL IN DILUTE CCl4 SOLUTION

1964 ◽  
Vol 42 (2) ◽  
pp. 347-352 ◽  
Author(s):  
P. J. Krueger ◽  
H. D. Mettee
Keyword(s):  
Infrared Spectroscopy ◽  
Room Temperature ◽  
Conformational Equilibrium ◽  
Spectroscopic Studies ◽  
Rotational Isomerism ◽  
Conformational Heterogeneity ◽  
Stable Conformer ◽  
Oh Groups ◽  
Equilibrium Scheme ◽  
Ccl4 Solution

High-resolution infrared spectroscopy indicates that the fundamental OH stretching band of 1-propanol in dilute CCl4 solution is composed of three components caused by rotational isomerism about the C—C and C—O bonds. Although the conformer with the CH3 and OH groups trans to each other is most heavily populated at room temperature, one of the two conformers having gauche CH3 and OH groups is thermodynamically most stable. A conformational equilibrium scheme is postulated in which the most stable conformer has a methyl C—H interacting with one of the lone pairs of electrons on the oxygen atom.

scholarly journals Molecular hydrophobicity at a macroscopically hydrophilic surface

2019 ◽  
Vol 116 (5) ◽  
pp. 1520-1525 ◽  
Author(s):  
Jenée D. Cyran ◽  
Michael A. Donovan ◽  
Doris Vollmer ◽  
Flavio Siro Brigiano ◽  
Simone Pezzotti ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Vibrational Frequency ◽  
Molecular Level ◽  
Water Molecules ◽  
Hydrophilic Surface ◽  
Oh Groups ◽  
Silica Surfaces ◽  
Fundamental Understanding ◽  
Dynamics Simulations ◽  
Hydrogen Bonded

Interfaces between water and silicates are ubiquitous and relevant for, among others, geochemistry, atmospheric chemistry, and chromatography. The molecular-level details of water organization at silica surfaces are important for a fundamental understanding of this interface. While silica is hydrophilic, weakly hydrogen-bonded OH groups have been identified at the surface of silica, characterized by a high O-H stretch vibrational frequency. Here, through a combination of experimental and theoretical surface-selective vibrational spectroscopy, we demonstrate that these OH groups originate from very weakly hydrogen-bonded water molecules at the nominally hydrophilic silica interface. The properties of these OH groups are very similar to those typically observed at hydrophobic surfaces. Molecular dynamics simulations illustrate that these weakly hydrogen-bonded water OH groups are pointing with their hydrogen atom toward local hydrophobic sites consisting of oxygen bridges of the silica. An increased density of these molecular hydrophobic sites, evident from an increase in weakly hydrogen-bonded water OH groups, correlates with an increased macroscopic contact angle.

Infrared spectra of pyridine sorbed on porous glass

1968 ◽  
Vol 46 (20) ◽  
pp. 3255-3261 ◽  
Author(s):  
M. J. D. Low ◽  
V. V. Subba Rao
Keyword(s):  
Hydrogen Bonding ◽  
Nitrogen Atom ◽  
Infrared Spectra ◽  
Porous Glass ◽  
Physical Adsorption ◽  
Hydrogen Atoms ◽  
Oh Groups ◽  
Pure Silica ◽  
Hydrogen Bonded

Infrared spectra were recorded of pyridine (PY) sorbed on highly dehydroxylated, deuterated, and fluoridated porous glass, as well as on pure silica and boria-impregnated silica. The hydrogen atoms of sorbed PY exchange with surface OD groups. Physical adsorption occurs by hydrogen bonding of PY to SiOH and B—OH groups via the PY nitrogen atom; there is some interaction of the ring π system with OH groups. Surface B:PY complexes form by coordination of PY to boron; the B:PY may be hydrogen bonded to B—OH groups. Some PY dissociates, and OH groups are generated.

Color and Antioxidant Changes in Various Natural Rubber Processes

2015 ◽  
Vol 754-755 ◽  
pp. 230-234 ◽  
Author(s):  
Suwimon Siriwong ◽  
Adisai Rungvichaniwat ◽  
Pairote Klinpituksa ◽  
Khalid Hamid Musa ◽  
Aminah Abdullah
Keyword(s):  
Acetic Acid ◽  
Natural Rubber ◽  
Retention Index ◽  
Total Phenolic Content ◽  
Room Temperature ◽  
Phenolic Content ◽  
Total Phenolic ◽  
Lovibond Colorimeter

Fresh field natural rubber was coagulated by acetic acid, soaked in water at room temperature (WRT) or 70°C (W70) for 1 hr, and then dried in an oven at 40°C. Non-soaked natural rubber samples (NoW) served as a control. Two grades of natural rubber, namely air-dry sheet (ADS) and ribbed smoked sheet No.3 (RSS3) derived from the same latex, were also investigated. All dry rubber samples were characterized with Lovibond colorimeter according to ASTM D3157, as well as with a HunterLab spectrophotometer. Furthermore, all the dry rubber samples were dissolved in a chloroform:methanol mixture (4:1 v:v). The rubber was then precipitated out of the solution with methanol, and the remaining solution was quantitatively analyzed for total phenolic content (TPC). The plasticity retention index (PRI) was determined for all the dried rubber samples according to ASTM D3194. It was found that WRT, W70 and ADS were similar in lightness L*, while RSS3 had the lowest L*. W70 had the lowest redness a*, which increased in the order WRT, NoW, RSS3 and ADS. W70 also had the lowest yellowness b*, which increased in the order RSS3, NoW and WRT and ADS. Moreover, TPC was the lowest for the W70 sample, increasing in the order ADS, WRT, NoW and RSS3. The PRI was highest for W70, and decreased in the order WRT, RSS3, NoW and ADS. All of the PRI values observed were comparatively high relative to blocked standard Thai rubber 20 (STR20).

Study on the Synthesis of Isoamyl Acetate Catalyzed by Strong Acidic Cation Exchange Resin

2011 ◽  
Vol 396-398 ◽  
pp. 2411-2415 ◽  
Author(s):  
Ping Lan ◽  
Li Hong Lan ◽  
Tao Xie ◽  
An Ping Liao
Keyword(s):  
Acetic Acid ◽  
Reaction Time ◽  
Cation Exchanger ◽  
Cation Exchange Resin ◽  
Isoamyl Acetate ◽  
Molar Ratio ◽  
Esterification Reaction ◽  
Reaction Conditions ◽  
Optimum Reaction

Isoamyl acetate was synthesized from isoamylol and glacial acetic acid with strong acidic cation exchanger as catalyst. The effects of reaction conditions such as acid-alcohol ratio, reaction time, catalyst dosage to esterification reaction have been investigated and the optimum reaction conditions can be concluded as: the molar ratio of acetic acid to isoamylol 0.8:1, reaction time 2h, 25 % of catalyst (quality of acetic acid as benchmark). The conversion rate can reach up to 75.46%. The catalytic ability didn’t reduce significantly after reusing 10 times and the results showed that the catalyst exhibited preferably catalytic activity and reusability.

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