Investigation of ring and nitrogen inversion in N-Methyl-1,2,3,4-tetrahydroisoquinoline by dynamic N.M.R. methods

1976 ◽  
Vol 29 (7) ◽  
pp. 1445 ◽  
Author(s):  
M Davis ◽  
HM Hugel ◽  
R Lakhan ◽  
B Ternai
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Bonding ◽  
Vinyl Chloride ◽  
Low Ph ◽  
Inversion Barrier ◽  
Nitrogen Inversion ◽  
The Difference

ΔG? for the overall ring and nitrogen inversion barriers in N-methyl-1,2,3,4-tetrahydroisoquinoline has been found to be 35.2 kJ/mol in vinyl chloride, and 50.2 kJ/mol in aqueous solution. Both measurements are believed to reflect the height of the nitrogen inversion barrier. The difference is attributed to hydrogen bonding in the aqueous solution. At low pH anomalous inversion rates were obtained.

scholarly journals Theoretical Study of the Structures of 4-(2,3,5,6-Tetrafluoropyridyl)Diphenylphosphine Oxide and Tris(Pentafluorophenyl)Phosphine Oxide: Why Does the Crystal Structure of (Tetrafluoropyridyl)Diphenylphosphine Oxide Have Two Different P=O Bond Lengths?

Molecules ◽  
2020 ◽  
Vol 25 (12) ◽  
pp. 2778
Author(s):  
Joseph R. Lane ◽  
Graham C. Saunders
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Phosphine Oxide ◽  
Density Functional ◽  
Lone Pair ◽  
Diphenylphosphine Oxide ◽  
Functional Theory ◽  
Weak Hydrogen Bonding ◽  
Independent Molecules ◽  
The Difference

The crystal structure of 4-(2,3,5,6-tetrafluoropyridyl)diphenylphosphine oxide (1) contains two independent molecules in the asymmetric unit. Although the molecules are virtually identical in all other aspects, the P=O bond distances differ by ca. 0.02 Å. In contrast, although tris(pentafluorophenyl)phosphine oxide (2) has a similar crystal structure, the P=O bond distances of the two independent molecules are identical. To investigate the reason for the difference, a density functional theory study was undertaken. Both structures comprise chains of molecules. The attraction between molecules of 1, which comprises lone pair–π, weak hydrogen bonding and C–H∙∙∙arene interactions, has energies of 70 and 71 kJ mol−1. The attraction between molecules of 2 comprises two lone pair–π interactions, and has energies of 99 and 100 kJ mol−1. There is weak hydrogen bonding between molecules of adjacent chains involving the oxygen atom of 1. For one molecule, this interaction is with a symmetry independent molecule, whereas for the other, it also occurs with a symmetry related molecule. This provides a reason for the difference in P=O distance. This interaction is not possible for 2, and so there is no difference between the P=O distances of 2.

Application of MOSCED and UNIFAC to Screen Hydrophobic Solvents for Extraction of Hydrogen-Bonding Organics from Aqueous Solution

2007 ◽  
Vol 46 (13) ◽  
pp. 4621-4625 ◽  
Author(s):  
Timothy C. Frank ◽  
John J. Anderson ◽  
James D. Olson ◽  
Charles A. Eckert
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Bonding

scholarly journals Structure and hydrogen bonding of the hydrated selenite and selenate ions in aqueous solution

2014 ◽  
Vol 43 (17) ◽  
pp. 6315-6321 ◽  
Author(s):  
Lars Eklund ◽  
Ingmar Persson
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Bonding ◽  
Free Electron ◽  
Electron Pair ◽  
Bound Water ◽  
Water Molecules ◽  
Hydration Sphere ◽  
Free Electron Pair

The selenite ion has an asymmetric hydration sphere with loosely electrostatically bound water molecules outside the free electron pair.

scholarly journals Adsorption of Cr6+ Onto Unmodified and Hydrochloric Acid Modified African Nutmeg Pod (Monodora myristica) from Aqueous Solution

2019 ◽  
pp. 1-8
Author(s):  
F. U. Okwunodulu ◽  
H. O. Chukwuemeka-Okorie ◽  
N. M. Mgbemena ◽  
J. B. I. Kalu
Keyword(s):  
Aqueous Solution ◽  
Metal Ion ◽  
Correlation Coefficients ◽  
Freundlich Isotherm ◽  
Low Ph ◽  
Ion Concentration ◽  
Isotherm Models ◽  
Particle Sizes ◽  
Monodora Myristica ◽  
Best Fit

The removal of Cr6+ from aqueous solution using unmodified and hydrochloric modified African nutmeg pod was studied. The effects of particle size, pH and initial metal ions concentration adsorbed were investigated. The amount of metal ion adsorbed increased as the initial metal ion concentration increased and also decreased at low pH of 2 for both modified and unmodified African nutmeg pod.  400 µm and 250 µm were the optimum particle sizes for both modified and unmodified African nutmeg pod respectively, values given as 75.8 mg/g for the modified and 93.39 mg/g for the unmodified. Generally, it was observed that the unmodified African nutmeg pod showed greater adsorption capacity than the modified African nutmeg pod. The equilibrium experimental data were examined via Langmuir and Freundlich isotherm models.  Freundlich isotherm model gave the best fit for the data in both unmodified and modified African nutmeg pod based on the correlation coefficients (R2 values) gotten. The results of the study showed that the African nutmeg pod is efficient for the removal of Cr6+ from aqueous solutions especially when unmodified.

Beneficiation of Seafloor Massive Sulfides by Liquid-Liquid Extraction

2021 ◽  
pp. 1-35
Author(s):  
Yasuharu Nakajima ◽  
Yuta Yamabe ◽  
Toyohisa Fujita ◽  
Gjergj Dodbiba
Keyword(s):  
Aqueous Solution ◽  
Contact Angle ◽  
High Pressures ◽  
Sulfide Mineral ◽  
Contact Angles ◽  
Liquid Extraction ◽  
Massive Sulfides ◽  
Liquid Liquid Extraction ◽  
Pressure Extraction ◽  
The Difference

Abstract This paper addresses the applicability of liquid-liquid extraction for separating mineral particles by the difference in oil-water partition coefficient, for the seafloor mineral processing of Seafloor Massive Sulfides (SMSs). Measurements of contact angle of sulfide mineral – aqueous solution – oil systems under high-pressure conditions were performed to evaluate the efficiency of liquid-liquid extraction at high pressures. The results showed that the contact angle stayed around 80 - 100° at the pressure range up to 16MPa; and the changes in the contact angles were within 5° with varying pressure. Extraction experiments were carried out by using particles of an SMS ore, which contained Zinc (Zn), Lead (Pb), and Barium (Ba) in the grade of more than 10 mass% and Copper (Cu) in a small percentage, to evaluate the beneficiation performance of liquid-liquid extraction. In the experiments, extraction conditions such as the dosage of chemical reagents, and pH in the aqueous solution were varied to optimize both the recovery and selectivity of Cu, Zn, and Pb in the oil phase, and those of Ba in the water phase. The experimental results showed that the optimum condition was 200 g/t dosage - pH 7, where the grade and recovery were ca. 37 mass% and ca. 90 mass%, respectively. The beneficiation performance of liquid-liquid extraction would be comparable to that of flotation, adapted to the processing of other SMS ores.

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