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.

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.

Infrared spectroscopy of ferrihydrite: evidence for the presence of structural hydroxyl groups

Clay Minerals ◽  
1979 ◽  
Vol 14 (2) ◽  
pp. 109-114 ◽  
Author(s):  
J. D. Russell
Keyword(s):  
Infrared Spectroscopy ◽  
Ir Spectroscopy ◽  
Room Temperature ◽  
Adsorbed Water ◽  
Deformation Vibration ◽  
Hydroxyl Groups ◽  
Absorption Bands ◽  
Oh Groups ◽  
Structural Hydroxyl

AbstractIR spectroscopy has shown that adsorbed water is almost completely removed from ferrihydrite by evacuation at room temperature. Absorption bands at 3615 and 3430 cm−1 appearing thereafter are interpreted as arising from OH groups located respectively at the surface and deeper in the structure. These groups are readily converted to OD on treatment with D2O vapour and this has allowed the OH deformation vibration to be identified at 800 cm−1. It is proposed that OH groups in ferrihydrite are about half as numerous as those in akaganéite (β-FeOOH) and that they may occur in environments similar to those in this mineral. The formula for ferrihydrite proposed by earlier workers, 5 Fe2O3.9H2O, should thus be amended to Fe2O3. 2 FeOOH.2·6H2O in order to indicate the presence of structural OH groups. A re-appraisal of the ferrihydrite structure appears desirable.

scholarly journals Fourier Transformation Infrared Spectroscopic Studies of Acidity of NaH-13 X Zeolites

2018 ◽  
Vol 21 (3) ◽  
pp. 428-435
Author(s):  
Shatha Abd-Alhameed Al. Sofy
Keyword(s):  
Infrared Spectroscopy ◽  
Fourier Transformation ◽  
Spectroscopic Studies ◽  
Acid Sites ◽  
Weak Acid ◽  
Hydroxyl Groups ◽  
Absorption Bands ◽  
Oh Groups ◽  
Fourier Transformation Infrared Spectroscopy ◽  
X Zeolites

Fourier transformation Infrared spectroscopy (FTIR) has been used to characterize and measure the concentration of acid sites (Si-OH-Al groups) in NaH-13 X Zeolites. Ion exchange was followed by dealumination to get (28, 40, 65, 85.8 and 97.5 Wt. %) of NaH-13 X Zeolites samples. The conclusion of homogeneity of OH groups was obtained by analysis of Fourier transformation infrared spectroscopy absorption bands of OH groups after adsorption and desorption of Ammonia. It found that there were different acid sites on a broader absorption (3,800-3,000 cm-1) corresponds to hydroxyl groups of the less acidic Brønsted acid sites approximately at 3464cm-1 and the more acidic at 3441cm-1 and Lewis acid sites was found at 1636 cm-1 which is few and weak acid sites . It can be conclusion that concentrations of OH groups increased with increasing the exchange degree and delamination. The concentration of acid sites in samples were calculated from stretching frequencies and extinction coefficients of OH bands, also the frequency shift  ΔνOH = 23 cm-1 which was due to the hydrogen bonding of OH groups with ammonia in 97.5 % NaH-13 X Zeolites. Knowing the acidity of catalyst is important for the reactions which required acidic surface.

scholarly journals Bottom-Up Approach to Assess the Molecular Structure of Aqueous Poly(N-Isopropylacrylamide) at Room Temperature via Infrared Spectroscopy

2020 ◽  
Vol 124 (51) ◽  
pp. 11699-11710
Author(s):  
Habtom B. Gobeze ◽  
Jianbo Ma ◽  
Fedra M. Leonik ◽  
Daniel G. Kuroda
Keyword(s):  
Molecular Structure ◽  
Infrared Spectroscopy ◽  
Room Temperature ◽  
Bottom Up

scholarly journals Structure and Properties of Ln2MoO6 Oxymolybdates (Ln = La, Pr, Nd) Doped with Magnesium

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 611
Author(s):  
Ekaterina Orlova ◽  
Elena Kharitonova ◽  
Timofei Sorokin ◽  
Alexander Antipin ◽  
Nataliya Novikova ◽  
...  
Keyword(s):  
Rare Earth ◽  
Infrared Spectroscopy ◽  
Room Temperature ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Spectroscopy Data ◽  
Structure And Properties ◽  
Hygroscopic Properties ◽  
Thermogravimetric Studies ◽  
Mg Doped

The literature data and the results obtained by the authors on the study of the structure and properties of a series of polycrystalline and single-crystal samples of pure and Mg-doped oxymolybdates Ln2MoO6 (Ln = La, Pr, Nd) are analyzed. Presumably, the high-temperature phase I41/acd of Nd2MoO6 single crystals is retained at room temperature. The reason for the loss of the center of symmetry in the structures of La2MoO6 and Pr2MoO6 and the transition to the space group I4¯c2 is the displacement of oxygen atoms along the twofold diagonal axes. In all structures, Mg cations are localized near the positions of the Mo atoms, and the splitting of the positions of the atoms of rare-earth elements is found. Thermogravimetric studies, as well as infrared spectroscopy data for hydrated samples of Ln2MoO6 (Ln = La, Pr, Nd), pure and with an impurity of Mg, confirm their hygroscopic properties.

Characterization and catalytic properties of a saponite clay modified by acid activation

Clay Minerals ◽  
1997 ◽  
Vol 32 (4) ◽  
pp. 633-643 ◽  
Author(s):  
F. Kooli ◽  
W. Jones
Keyword(s):  
Infrared Spectroscopy ◽  
Room Temperature ◽  
Textural Properties ◽  
Acid Sites ◽  
Single Type ◽  
Activation Process ◽  
Acid Activation ◽  
Strongly Correlated ◽  
Lewis Site ◽  
Adsorbed Pyridine

AbstractA natural saponite was acid activated at room temperature or 90°C with different acid/clay ratios and the products were characterized by powder X-ray diffraction, infrared spectroscopy and thermogravimetry. The leaching of Mg from the octahedral sheets is enhanced by an increase in the acid/clay ratio and by an increase in temperature of activation. Textural properties are reported, and it appears that they are strongly correlated to the presence of a noncrystalline silica phase which is formed during the acid activation process. The desorption of cyclohexylamine indicates that for samples activated at 90°C the number of acid sites in the acidactivated saponites decreases following severe acid treatment. Infrared spectroscopy of adsorbed pyridine on samples after calcination at 500°C suggests that acid activation at 90°C produces a single type of Bronsted site but two types of Lewis sites whereas activation at room temperature results in only one type of Lewis site in addition to a Brønsted site. The two Lewis sites are suggested to originate from residual Al in the clay structure and to AI exsolved from the layers during activation. The dehydration of pentan-1-ol has been used as a further probe to measure acidity by monitoring the degree of conversion and selectivity for the different samples.

scholarly journals Insertion of Phosphenium Ions into a Bicyclo[1.1.0]Tetraphosphabutane Iron Complex

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3920
Author(s):  
Martin Weber ◽  
Gábor Balázs ◽  
Alexander V. Virovets ◽  
Eugenia Peresypkina ◽  
Manfred Scheer
Keyword(s):  
Diffraction Analysis ◽  
Room Temperature ◽  
31P Nmr ◽  
Spectroscopic Studies ◽  
Iron Complex ◽  
The Novel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Phosphenium Ions

By reacting [{Cp‴Fe(CO)2}2(µ,η1:1-P4)] (1) with in situ generated phosphenium ions [Ph2P][A] ([A]− = [OTf]− = [O3SCF3]−, [PF6]−), a mixture of two main products of the composition [{Cp‴Fe(CO)2}2(µ,η1:1-P5(C6H5)2)][PF6] (2a and 3a) could be identified by extensive 31P NMR spectroscopic studies at 193 K. Compound 3a was also characterized by X-ray diffraction analysis, showing the rarely observed bicyclo[2.1.0]pentaphosphapentane unit. At room temperature, the novel compound [{Cp‴Fe}(µ,η4:1-P5Ph2){Cp‴(CO)2Fe}][PF6] (4) is formed by decarbonylation. Reacting 1 with in situ generated diphenyl arsenium ions gives short-lived intermediates at 193 K which disproportionate at room temperature into tetraphenyldiarsine and [{Cp‴Fe(CO)2}4(µ4,η1:1:1:1-P8)][OTf]2 (5) containing a tetracyclo[3.3.0.02,7.03,6]octaphosphaoctane ligand.

scholarly journals Spectroscopic Studies of Er3+-Yb3+ Codoped Multicomposition Tellurite Oxide Glass

2014 ◽  
Vol 895 ◽  
pp. 323-333 ◽  
Author(s):  
Sharudin Omar Baki ◽  
L.S. Tan ◽  
C.S. Kan ◽  
Halimah Mohamed Kamari ◽  
A.S.M. Noor ◽  
...  
Keyword(s):  
Room Temperature ◽  
Near Infrared ◽  
Transition Probabilities ◽  
Branching Ratios ◽  
Spectroscopic Studies ◽  
Oxide Glass ◽  
Near Infrared Spectra ◽  
Intensity Parameters ◽  
Measured Absorption

Multicomposition of Er3+-Yb3+codoped tellurite oxide, TeO2-ZnO-PbO-TiO2-Na2O glass has been investigated. Detailed spectroscopic study of the Judd-Ofelt analysis has been performed from the measured absorption spectrum in order to obtain the intensity parameters Ωt(t=2, 4, 6). The calculated Ωtvalues were then utilized in the determination of transition probabilities, radiative lifetimes and branching ratios of the Er3+transitions between theJ(upper)-J(lower) manifolds. Both visible upconversion and near-infrared spectra were characterized under the 980 nm laser diode excitation at room temperature.

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