Isomer-selective infrared spectroscopy of the cationic trimethylamine dimer to reveal its charge sharing and enhanced acidity of the methyl groups

2014 ◽  
Vol 16 (20) ◽  
pp. 9619-9624 ◽  
Author(s):  
Yoshiyuki Matsuda ◽  
Yuichiro Nakayama ◽  
Naohiko Mikami ◽  
Asuka Fujii
Keyword(s):  
Hydrogen Bond ◽  
Infrared Spectroscopy ◽  
Methyl Groups ◽  
Charge Sharing

The isomer-selective infrared spectroscopy revealed the charge-shared (hemibond) and the C⋯HN hydrogen-bond structures of the trimethylamine dimer cation.

scholarly journals (E)-N-{3-[(m-Tolylimino)methyl]pyridin-2-yl}pivalamide

IUCrData ◽  
2017 ◽  
Vol 2 (11) ◽  
Author(s):  
Şehriman Atalay ◽  
Semra Gerçeker ◽  
Seher Meral
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Dihedral Angle ◽  
Torsion Angle ◽  
Title Compound ◽  
Methyl Groups ◽  
Compound C ◽  
Benzene Rings

In the title compound, C18H21N3O, the dihedral angle between the pyridine and benzene rings is 30.53 (7)° and the C—C=N—C torsion angle is −170.6 (2)°. An intramolecular N—H...N hydrogen bond generates anS(6) ring. In the crystal, very weak C—H...O hydrogen bonds link the molecules intoC(8) [101] chains. Thetert-butyl methyl groups are disordered over two sets of sites in a 0.783 (4):0.217 (4) ratio.

scholarly journals Study on the unsaturated hydrogen bond behavior of bio-based polyamide 56

e-Polymers ◽  
2019 ◽  
Vol 19 (1) ◽  
pp. 23-31
Author(s):  
Shouyun Zhang ◽  
Jinghong Ma
Keyword(s):  
Hydrogen Bond ◽  
Infrared Spectroscopy ◽  
Hydrogen Bonds ◽  
Metal Oxides ◽  
Significant Influence ◽  
Polymer Chains ◽  
Experimental Results ◽  
Bond Behavior ◽  
Unit Structure

AbstractIn this paper, the unsaturated hydrogen bonds (H-bonds) of the bio-based polyamide 56 (PA56) with an odd-even unit structure were analyzed by infrared spectroscopy. It was proved that the bio-based PA56 had less saturated H-bonds, which became attenuated and blue-shifted at the temperature exceeding 260°C. Besides, as H-bond was decayed and broken, new unsaturated H-bonds readily formed. Moreover, the experimental results obtained strongly indicate that the unsaturated H-bonds of bio-based polyamide 56 could react with polar metal oxides. Besides, the intercalation of montmorillonite was found to have a significant influence on the hydrogen bond between polymer chains.

scholarly journals New insight into single phase formation of capric acid/menthol eutectic mixtures by Fourier-transform infrared spectroscopy and differential scanning calorimetry

2020 ◽  
Vol 19 (2) ◽  
pp. 361-369 ◽  
Author(s):  
Hiba H. Ali ◽  
Mowafaq M. Ghareeb ◽  
Mayyas Al-Remawi ◽  
Faisal T. Al-Akayleh
Keyword(s):  
Differential Scanning Calorimetry ◽  
Hydrogen Bond ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Fourier Transform Infrared Spectroscopy ◽  
Bond Formation ◽  
Capric Acid ◽  
Fourier Transform Infrared ◽  
Scanning Calorimetry ◽  
Hydrogen Bond Formation

Purpose: To examine the structural changes of a eutectic mixture comprising capric acid and menthol which are commonly used in pharmaceutical applications. Methods: A phase diagram was constructed by quantitative mixing of capric acid and menthol under controlled conditions until a single liquid phase was formed. Eutectic mixtures of capric acid: menthol at the ratios of 3:2, 1:4, 1:1, 2:3, and 1:4 were prepared. Hydrogen bond formation and conformational changes were analyzed using Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). Microscopic imaging was carried out to capture phase change events upon increasing temperature. Results: Menthol confirmed the intact structure of a hexagonal ring. The high degree of broadening of the menthol O-H groups indicates hydrogen bond formation. FTIR band changes related to capric acid suggest a break-up of the methylene arrangement structure due to changes in the C-H band frequencies. The red shift encountered in C=O stretching band emphasizes hydrogen bond formation taking place between the oxygen atom of the hydroxyl group comprising the carboxylic moiety of capric acid and the hydrogen atom of menthol hydroxyl group. DSC results indicate the presence of two polymorphs of the capric acid/ menthol complex. Both exhibited crystallization and conformational change exotherms in addition to two melting endotherms as result of transformation of crystalline components to become partially crystalline due to hydrogen bond formation. Conclusion: The interaction between capric acid and menthol results in a typical preparation of deep eutectic systems that can act as natural-based solvents in numerous pharmaceutical applications. Keywords: Eutectic system, Capric acid, Menthol, Differential scanning calorimetry, DSC, Fourier transform infrared spectroscopy, FTIR

The Role of Methyl Groups in the Formation of Hydrogen Bond in DMSO−Methanol Mixtures

2006 ◽  
Vol 128 (5) ◽  
pp. 1438-1439 ◽  
Author(s):  
Qingzhong Li ◽  
Guoshi Wu ◽  
Zhiwu Yu
Keyword(s):  
Hydrogen Bond ◽  
Methyl Groups

scholarly journals 3-Acetyl-1-(3-methylphenyl)thiourea

2012 ◽  
Vol 68 (8) ◽  
pp. o2574-o2574 ◽  
Author(s):  
B. Thimme Gowda ◽  
Sabine Foro ◽  
Sharatha Kumar
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Benzene Ring ◽  
Title Compound ◽  
Side Chain ◽  
Maximum Deviation ◽  
Methyl Groups ◽  
Compound C ◽  
Ring Motif

In the crystal structure of the title compound, C10H12N2OS, the conformation of the two N—H bonds areantito each other. The amide C=O and the C=S are are alsoantito each other. The N—H bond adjacent to the benzene ring issynto them-methyl groups. The dihedral angle between the benzene ring and the side chain [mean plane of atoms C—C(O)N—C—N; maximum deviation 0.029 (2) Å] is 14.30 (7)°. There is an intramolecular N—H...O hydrogen bond generating anS(6) ring motif. In the crystal, the molecules are linkedviaN—H...) hydrogen bonds, forming chains propagating along [001]. The S atom is disordered and was refined using a split model [occupancy ratio 0.56 (4):0.44 (4)].

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