Determination of thermodynamic functions by means of infrared spectroscopy. II. Axial and equatorial hydrogen bonds

1972 ◽  
Vol 37 (6) ◽  
pp. 1990-1992 ◽  
Author(s):  
M. Horák ◽  
V. Šára ◽  
J. Moravec
Keyword(s):  
Infrared Spectroscopy ◽  
Hydrogen Bonds ◽  
Thermodynamic Functions

Determination of thermodynamic functions by means of infrared spectroscopy. The accuracy in -ΔH determination; Formation of complexes phenol-pyridine and its homologues

1979 ◽  
Vol 44 (1) ◽  
pp. 148-156 ◽  
Author(s):  
Václav Šára ◽  
Jaromír Moravec ◽  
Milan Horák
Keyword(s):  
Infrared Spectroscopy ◽  
Thermodynamic Functions ◽  
Ionization Constants ◽  
Experimental Conditions ◽  
Pyridine Bases ◽  
Methyl Derivatives ◽  
Pyridinic Nitrogen ◽  
Influence Of Substituents ◽  
Formation Of Complexes

Values of thermodynamic functions -ΔH, -ΔG, and -ΔS of the complex formation between molecules of pyridine (and its methyl derivatives) and phenol in CCl4 solutions were determined using infrared spectroscopy. After optimalizing experimental conditions the error in -ΔH determination does not exceed 0.2%; this accuracy is sufficiently high to investigate the influence of substituents on the pyridinic nitrogen basicity. The values of -ΔH determined in this way correlate linearly with values of ionization constants of pyridine bases.

Near Infrared Spectroscopy Used in Purification and Determination of Pharmaceutical Cocrystal

2013 ◽  
Vol 41 (12) ◽  
pp. 1928
Author(s):  
Zong-Liang CHI ◽  
Miao-Miao WANG ◽  
Xiao-Dong CONG ◽  
Shao-Guang LIU ◽  
Bao-Chang CAI
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Pharmaceutical Cocrystal

The protonation of the ethylenediphosphinetetraacetate anion and the crystal structure of the bis (hydrogen bromide) of ethylenediphosphinetetraacetic acid

1981 ◽  
Vol 46 (12) ◽  
pp. 3063-3073 ◽  
Author(s):  
Jana Podlahová ◽  
Bohumil Kratochvíl ◽  
Vratislav Langer ◽  
Josef Šilha ◽  
Jaroslav Podlaha
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Structure Determination ◽  
Free Acid ◽  
Hydrogen Bromide ◽  
Carboxyl Groups ◽  
Spectroscopic Methods ◽  
X Ray ◽  
Partial Formation

The equilibria and mechanism of addition of protons to the ethylenediphosphinetetraacetate anion (L4-) were studied in solution by the UV, IR, 1H and 31P NMR spectroscopic methods. A total of six protons can be bonded to the anion. They are added stepwise, first with partial formation of zwitterions containing P-H bonds, which then dissociate with formation of the free acid, H4L, where all four protons are bonded in carboxyl groups. The formation of zwitterions is strongly dependent on the concentration. In the final stage, the acid bonds two additional protons to form the bis-phosphonium cation, H6L2+. A number of isostructural salts containing this cation, H4L.2 HX (X = Cl, Br, I), have been prepared. The X-ray crystal structure determination of the bromide confirmed the expected arrangement. The bromide crystals are monoclinic, a = 578.2, b = 1 425.0, c = 1 046.7 pm, β = 103.07° with a space group of P21/c, Z = 2. The final R factor was 0.059 based on 1 109 observed reflections. The structure consists of H6L2+ cations containing protons bonded to phosphorus atoms (P-H distance 134 pm) and of bromide anions, located in gaps which are also sufficiently large for I- anions in the isostructural iodide. The interbonding of phosphonium cations proceeds through hydrogen bonds, C-OH...O=C, in which the O...O distance is 275.3 pm.

Determination of main raw material source in bar soaps using mid-infrared spectroscopy combined with classification tools

2021 ◽  
Vol 164 ◽  
pp. 106029
Author(s):  
Diego Maciel Gerônimo ◽  
Sheila Catarina de Oliveira ◽  
Frederico Luis Felipe Soares ◽  
Patricio Peralta-Zamora ◽  
Noemi Nagata
Keyword(s):  
Infrared Spectroscopy ◽  
Raw Material ◽  
Material Source ◽  
Mid Infrared ◽  
Mid Infrared Spectroscopy
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