HYDROGEN BONDING IN THE AMINE HYDROHALIDES: III. NEAR-INFRARED SPECTRA OF ALIPHATIC AMINE HYDROHALIDES

1960 ◽  
Vol 38 (10) ◽  
pp. 1901-1910 ◽  
Author(s):  
P. Sauvageau ◽  
C. Sandorfy
Keyword(s):  
Hydrogen Bonding ◽  
Secondary Amine ◽  
Infrared Spectra ◽  
Near Infrared ◽  
Potential Surface ◽  
Aliphatic Amine ◽  
Bending Vibrations ◽  
Near Infrared Spectra ◽  
Combination Bands

The first overtones of the [Formula: see text] stretching fundamentals are very weak and difficult to locate. Binary combinations between [Formula: see text] stretching and [Formula: see text] bending vibrations and also [Formula: see text] stretching–bending combinations fall into the 4600–4400 cm−1 area for primary and secondary amine hydrohalides and are much stronger. The intensity of these combination bands is not due to the anharnionicity of the potential surface but to the electrical anharmonicity of bending vibrations.

HYDROGEN BONDING IN THE AMINE HYDROHALIDES: II. THE INFRARED SPECTRUM FROM 4000 TO 2200 CM−1

1960 ◽  
Vol 38 (1) ◽  
pp. 34-44 ◽  
Author(s):  
C. Brissette ◽  
C. Sandorfy
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Infrared Spectrum ◽  
Infrared Spectra ◽  
Primary Amine ◽  
Lithium Fluoride ◽  
Aliphatic Amine ◽  
Combination Bands ◽  
Lower Frequencies ◽  
Amine Salts

The infrared spectra of a number of amine hydrohalides have been measured in the lithium fluoride region.Hydrogen bonding and the torsional oscillations of the [Formula: see text] groups influence these spectra characteristically. The [Formula: see text] stretching frequencies give broad or fairly broadbands. They are near 3000 cm−1 for aliphatic primary amine salts. The corresponding band lies at somewhat lower frequencies for secondary amine salts and much lower for tertiary ones. The aromatic amine hydrohalides exhibit these bands at lower frequencies than do the aliphatic amine salts of the same order. There is a shift to higher frequencies in the series hydrochloride, hydrobromide, hydriodide.All these spectra contain a number of sharper bands which may or may not coincide with the hydrogen-bonded stretching bands. These are combination bands involving mainly deformation vibrations, and they shift to lower frequencies, throughout the series hydrochloride, hydrobromide, hydriodide.The importance of electrical anharmonicity for the appearance of these bands is stressed.The hydrogen bonds in amine hydrohalides appear to be largely electrostatic in character.

Discrimination of Organic Solvents Using an Infrared-Emitting Diode-Based Analyzer. Part I: Feasibility

1995 ◽  
Vol 49 (11) ◽  
pp. 1590-1597 ◽  
Author(s):  
Anthony S. Bonanno ◽  
Peter R. Griffiths
Keyword(s):  
Hydrogen Bonding ◽  
Temperature Variation ◽  
Organic Solvents ◽  
Infrared Spectra ◽  
Mahalanobis Distance ◽  
Near Infrared ◽  
Short Wave ◽  
Multivariate Statistical Methods ◽  
Multivariate Statistical ◽  
Near Infrared Spectra

This report demonstrates the feasibility of discriminating organic solvents on the basis of short-wave near-infrared spectra (from 0.7 to 1.1 μm). Both library searching and multivariate statistical methods were applied to 8-cm−1 spectra and to spectra de-resolved to the point achievable with an analyzer using discrete infrared-emitting diode sources. Library searching performed satisfactorily if the unknown and library spectra were collected under reasonably similar conditions, but performed poorly if the temperature of hydrogen-bonding solvents was varied. A multivariate discrimination technique based on Mahalanobis distance computation was capable of discriminating between several alcohols while allowing for a temperature variation of 20°C. These results indicate that a very low resolution (on the order of 100 cm−1) short-wave near-infrared analyzer can achieve successful discrimination between similar solvents under variable conditions.

scholarly journals Near-Infrared Spectroscopy Study of Serpentine Minerals and Assignment of the OH Group

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1130
Author(s):  
Shaokun Wu ◽  
Mingyue He ◽  
Mei Yang ◽  
Biyao Zhang ◽  
Feng Wang ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Infrared Spectra ◽  
Near Infrared ◽  
Bending Vibrations ◽  
Bending Vibration ◽  
Serpentine Minerals ◽  
Near Infrared Spectra ◽  
Stretching Vibration ◽  
Serpentine Mineral

Three different kinds of serpentine mineral samples were investigated using Fourier transform near-infrared spectroscopy (FTNIR). The results show that there are obvious differences in the characteristic infrared spectra of the three serpentine group minerals (lizardite, chrysotile, and antigorite), which can easily be used to identify these serpentine minerals. The combination of weak and strong peaks in the spectrum of lizardite appears at 3650 and 3690 cm−1, while the intensities of the peaks at 4281 and 4301 cm−1 (at 7233 and 7241 cm−1, respectively) are similar. A combination of weak and strong peaks in chrysotile appears at 3648 and 3689 cm−1 and at 4279 and 4302 cm−1, and a single strong peak appears at 7233 cm−1. In antigorite, there are strong single peaks at 3674, 4301, and 7231 cm−1, and the remaining peaks are shoulder peaks or are not obvious. The structural OH mainly appears as characteristic peaks in four regions, 500–720, 3600–3750, 4000–4600, and 7000–7600 cm−1, corresponding to the OH bending vibration, the OH stretching vibration, the OH secondary combination vibration, and the OH overtone vibration, respectively. In the combined frequency vibration region, the characteristic peak near 4300 cm−1 is formed by the combination of the internal and external stretching vibrations and bending vibrations of the structural OH group. The overtone vibrations of the OH stretching vibration appear near 7200 cm−1, and the practical factor is about 1.965. The near-infrared spectra of serpentine minerals are closely related to their structural differences and isomorphous substitutions. Therefore, near-infrared spectroscopy can be used to identify serpentine species and provides a basis for studies on the genesis and metallogenic environment of these minerals.

Measurement of the Near-Infrared Spectra of H2O-SiOH-Bearing Siliceous Materials at High Pressures

1979 ◽  
Vol 33 (5) ◽  
pp. 495-499 ◽  
Author(s):  
Klaus Langer ◽  
Werner A. P. Luck ◽  
Otto Schrems
Keyword(s):  
Infrared Spectra ◽  
Near Infrared ◽  
High Pressures ◽  
Band System ◽  
High Energy ◽  
Single Beam ◽  
Near Infrared Spectra ◽  
Diamond Anvil ◽  
Combination Bands ◽  
Energy Components

Techniques for measuring OH-combination bands of water and other OH-group bearing solid or liquid materials in the near-infrared (6000 to 4000 cm−1) at high pressures by means of a modified diamond anvil cell, adapted to a single beam micro-spectrometer, have been developed and applied to opals, i.e., minerals in the system SiO2-H2O containing relatively high amounts of water and SiOH. Liquid embedding, using the gasket technique and poly-fluoro-carbon oils as embedding liquids, which provide a hydrostatic pressure environment at least up to 50 kbar, is applied for solid materials. The high pressure near-infrared spectra of gel-like, spherulitic opal-AG show a strong relative decrease of the high energy components of the complex (v1 + v2)H2O-band system at around 5200 cm−1 in favor of the low energy components of this band system. This is tentatively interpreted as due to an increase of fully hydrogen bonded water at the expense of water in which only one OH-group is H-bonded. The corresponding effect in opal-AN with a glass-like continuous SiO4/2-tetrahedral network is much smaller.

Polarized overtone-combination bands in the near-infrared spectra of K2SnCl4•H2O and KSnCl3•H2O at cryogenic temperatures

1986 ◽  
Vol 64 (5) ◽  
pp. 1012-1019 ◽  
Author(s):  
Ian M. Walker ◽  
Paul J. McCarthy
Keyword(s):  
Water Molecule ◽  
Normal Mode ◽  
Infrared Spectra ◽  
Near Infrared ◽  
Water Molecules ◽  
Site Symmetry ◽  
Cryogenic Temperatures ◽  
Near Infrared Spectra ◽  
Combination Bands ◽  
Anharmonicity Constants

The near-infrared (nir) spectra of K2SnCl4•H2O and KSnCl3•H2O contain many highly polarized absorptions, due largely, if not completely, to combinations of vibrations of the water molecules in the crystals. The polarization of the absorptions can be related to the site symmetry of the water molecule. In K2SnCl4•H2O combination bands based on rocking, wagging, and twisting librations are seen, from which it is possible to definitively identify the rocking libration. The librations are much less in evidence in the spectra of KSnCl3•H2O. Sets of normal mode anharmonicity constants have been calculated from the energies of the absorptions.

Rapid Determining Contents of the Rhubarb Anthraquinones Compounds by Support Vector Machines Modeling based on Near Infrared Spectra

2020 ◽  
Vol 16 ◽  
Author(s):  
Linqi Liu ◽  
JInhua Luo ◽  
Chenxi Zhao ◽  
Bingxue Zhang ◽  
Wei Fan ◽  
...  
Keyword(s):  
Infrared Spectra ◽  
Near Infrared ◽  
Mean Squared Error ◽  
Rapid Determination ◽  
Partial Least Square ◽  
Least Square ◽  
Support Vector ◽  
Near Infrared Spectra ◽  
Aloe Emodin ◽  
Relative Differences

BACKGROUND: Measuring medicinal compounds to evaluate their quality and efficacy has been recognized as a useful approach in treatment. Rhubarb anthraquinones compounds (mainly including aloe-emodin, rhein, emodin, chrysophanol and physcion) are its main effective components as purgating drug. In the current Chinese Pharmacopoeia, the total anthraquinones content is designated as its quantitative quality and control index while the content of each compound has not been specified. METHODS: On the basis of forty rhubarb samples, the correlation models between the near infrared spectra and UPLC analysis data were constructed using support vector machine (SVM) and partial least square (PLS) methods according to Kennard and Stone algorithm for dividing the calibration/prediction datasets. Good models mean they have high correlation coefficients (R2) and low root mean squared error of prediction (RMSEP) values. RESULTS: The models constructed by SVM have much better performance than those by PLS methods. The SVM models have high R2 of 0.8951, 0.9738, 0.9849, 0.9779, 0.9411 and 0.9862 that correspond to aloe-emodin, rhein, emodin, chrysophanol, physcion and total anthraquinones contents, respectively. The corresponding RMSEPs are 0.3592, 0.4182, 0.4508, 0.7121, 0.8365 and 1.7910, respectively. 75% of the predicted results have relative differences being lower than 10%. As for rhein and total anthraquinones, all of the predicted results have relative differences being lower than 10%. CONCLUSION: The nonlinear models constructed by SVM showed good performances with predicted values close to the experimental values. This can perform the rapid determination of the main medicinal ingredients in rhubarb medicinal materials.

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