Functional groups prediction from infrared spectra based on computer-assist approaches

Structure identification of chemical substances from infrared spectra can be done with various approaches: a theoretical method using quantum chemistry calculations, an inductive method using standard spectral databases of known chemical substances, and an empirical method using rules between spectra and structures. For various reasons, it is difficult to definitively identify structures with these methods. The relationship between structures and infrared spectra is complicated and nonlinear, and for problems with such nonlinear relationships, neural networks are the most powerful tools. In this study, we have evaluated the performance of a neural network system that mimics the methods used by specialists to identify chemical structures from infrared spectra. Neural networks for identifying over 100 functional groups have been trained by using over 10 000 infrared spectral data compiled in the integrated spectral database system (SDBS) constructed in our laboratory. Network structures and training methods have been optimized for a wide range of conditions. It has been demonstrated that with neural networks, various types of functional groups can be identified, but only with an average accuracy of about 80%. The reason that 100% identification accuracy has not been achieved is discussed.

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Effect of functional group conformation on the infrared spectra of some gem difunctional phenylethylene derivatives

Canadian Journal of Chemistry ◽

10.1139/v69-520 ◽

1969 ◽

Vol 47 (17) ◽

pp. 3147-3152 ◽

Cited By ~ 11

Author(s):

D. J. Currie ◽

C. E. Lough ◽

F. K. McClusky ◽

H. L. Holmes

Keyword(s):

Absorption Band ◽

Functional Groups ◽

Infrared Spectra ◽

Functional Group ◽

Plane Deformation ◽

Carbonyl Groups ◽

Deformation Bands ◽

Or Groups ◽

Out Of Plane ◽

Stretching Vibrations

Except for the benzalmalononitriles, two functional group stretching vibrations occur in the infrared (i.r.) spectra of the β,β-difunctional-styrenes with similar functional groups. For geometrically homogeneous compounds with dissimilar functional groups only one absorption band occurs for each functional group. The two bands for similar functional groups have been ascribed to S-cis- and S-trans-conformations of the carbonyl groups with respect to the ethylene and variation in the frequencies of each of these oriented carbonyls to rotation of the functional group or groups out of the plane of the ethylene by steric factors.Frequencies for ethylenic C—H out of plane deformation bands for β-monofunctional styrenes accorded with those already assigned to this vibration. A similar assignment could not be made for the difunctional analogues.

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On Line Infrared Identification of Gas Chromatography Effluents

Applied Spectroscopy ◽

10.1366/000370275774455491 ◽

1975 ◽

Vol 29 (1) ◽

pp. 24-28 ◽

Cited By ~ 6

Author(s):

B. Katlafsky ◽

M. W. Dietrich

Keyword(s):

Gas Chromatography ◽

Functional Groups ◽

Infrared Spectra ◽

Functional Group ◽

Fold Increase ◽

Polar Compounds ◽

Signal Averaging ◽

On Line ◽

Averaging Techniques

On-line infrared spectra obtained with the Norcon RS-1 gas chromatographic identifier are of sufficient quality for qualitative identification of functional groups, chemical classes, or chemical entities. Identification limits for chemical entities vary between 20 and 200 µg, polar compounds having higher sensitivities. Functional group identifications can be made with correspondingly smaller samples. A 5-fold increase in sensitivity was demonstrated using signal-averaging techniques.

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Removing Mechanism of Bacteria of LKD in Bauxite Flotation Separation

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.454.246 ◽

2012 ◽

Vol 454 ◽

pp. 246-250

Author(s):

Shu Yong Yang ◽

Shu Juan Dai ◽

Lian Tao Yu ◽

Li Jia Deng

Keyword(s):

Infrared Spectroscopy ◽

Functional Groups ◽

Infrared Spectra ◽

Electric Potential ◽

Strong Acid ◽

Weak Acid ◽

Reverse Flotation ◽

Spectroscopy Analysis ◽

Acid Ph ◽

Neutral Conditions

The depressing function of bacteria of LKD on diaspore and kaolinite is studied through flotation experiments, mineral ζ-electric potential and infrared spectroscopy analysis. Waste beer has better selective and depressing effects on diaspore in the range pH 2-10 than starch-like substances do. The analysis of mineral ζ-electric potential and infrared spectra shows that the bacteria of LKD is chemically adsorbed to diaspore via its –COOH and stays on the surface of mineral firmly. Meanwhile, the functional groups -OH of yeast itself and some -COOH are hydrophilic, which helps the mineral being hydrophilic as well. Although the structure of phyllosilicate kaolinite determines its good floatability on the condition of strong acid, the recovery of diaspore by yeast is 30% more than kaolinite when the diaspore is depressed by bacteria of LKD on the condition of weak acid, pH-6. It indicates the possibility of Al-Si separation by reverse-flotation under neutral conditions.

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Infrared Signatures of Prebiology - or Biology?

International Astronomical Union Colloquium ◽

10.1017/s0252921100014603 ◽

1997 ◽

Vol 161 ◽

pp. 61-76

Author(s):

Nalin C. Wickramasinghe ◽

Fred Hoyle ◽

Shirwan Al-Mufti ◽

Daryl H. Wallis

Keyword(s):

Functional Groups ◽

Infrared Spectra ◽

Widespread Occurrence ◽

Interstellar Grains ◽

Wide Range

AbstractData on infrared spectra of astronomical sources and on the unidentified infrared bands is reviewed and compared with a range of predictions from organic models of interstellar grains. The best fits to a wide range of data appear to require the widespread occurrence of functional groups distributed in exactly the proportions that characterise biosystems. The question of whether these agreements are consistent with extraterrestrial prebiology, or even cosmic biology is discussed.

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Study of the low intensity spectral bands within the infrared spectra of kernels of high-yielding maize hybrids

Zbornik Matice srpske za prirodne nauke ◽

10.2298/zmspn1936033r ◽

2019 ◽

pp. 33-42

Author(s):

Cedomir Radenovic ◽

Georgij Maksimov ◽

Olga Slatinskaya ◽

Fedor Protopopov ◽

Nenad Delic ◽

...

Keyword(s):

Functional Groups ◽

Organic Compounds ◽

Infrared Spectra ◽

Wave Number ◽

Unstable State ◽

Number Range ◽

Maize Hybrids ◽

Low Intensity ◽

Spectral Bands ◽

Wave Number Range

The nature, role, and significance of low intensity spectral bands con?tained within the infrared spectra of kernels of high-yielding maize hybrids: ZP 341, ZP 434, and ZP 505 were observed in this study. The observations were performed to identify or?ganic molecules and their structural properties. The occurrence of unstable state of organic compounds and their functional groups are conditioned by such a process. The set hypoth?esis holds that there is a necessity to study the existence of many and low intensity spectral bands, not observed so far, occurring in different patterns (low intensity bands, single or grouped). They should be observed and the dynamics of their formation, caused by their different movements, including the possibility of their cancellation or amplification, should be explained. Such spectral bands most often appear in the wave number range of 400-950 cm-1. They occur in several wave numbers up to 3,000 cm-1 and are caused by different types of vibration movements (valence and deformation vibrations) of organic compounds and their functional groups: primary, secondary, and tertiary amides, proteins, free amino acids, alkanes, alkenes, aldehydes, ketones, aromatic compounds, cellulose, carbohydrates, car?boxylic acids, ethers, and alcohols. An unbiased analysis of low intensity spectral bands of maize hybrid kernels reveals that their occurrence is similar. Small differences, for some cases of the occurrence of low intensity spectral bands, can barely be ascertained. In this way, it is possible to establish not only the chemical composition of organic compounds of kernels of observed maize hybrids, but also it is possible to indicate their unstable, confor?mational, and functional properties.

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