scholarly journals Behavior of Organic Compounds with Different Functional Groups based on Surface Tension, Ramsey-Shields-EÖTVÖS Constants (k), Order of Association (x) and Trouton’s Rule

2018 ◽  
Vol 3 (1) ◽  
pp. 58-61 ◽  
Author(s):  
R. Sanjeev ◽  
V. Jagannadham
Keyword(s):  
Surface Tension ◽  
Functional Groups ◽  
Organic Compounds ◽  
Discriminative Behavior ◽  
Associative Behavior

Hydrocarbons and organic compounds having different functional groups with hetero atoms have shown a discriminative behavior toward surface tension, EÖTVÖS constants (k), order of association (x) and Trouton’s rule. This was explained in terms of associative and non-associative behavior of these compounds.

scholarly journals Non-Enzymatic Desymmetrization Reactions in Aqueous Media

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 720
Author(s):  
Satomi Niwayama
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Functional Groups ◽  
Organic Compounds ◽  
Recent Progress ◽  
Aqueous Media ◽  
Building Blocks ◽  
Organic Reactions ◽  
Environmentally Benign ◽  
Enzymatic Desymmetrization

Symmetric organic compounds are generally obtained inexpensively, and therefore they can be attractive building blocks for the total synthesis of various pharmaceuticals and natural products. The drawback is that discriminating the identical functional groups in the symmetric compounds is difficult. Water is the most environmentally benign and inexpensive solvent. However, successful organic reactions in water are rather limited due to the hydrophobicity of organic compounds in general. Therefore, desymmetrization reactions in aqueous media are expected to offer versatile strategies for the synthesis of a variety of significant organic compounds. This review focuses on the recent progress of desymmetrization reactions of symmetric organic compounds in aqueous media without utilizing enzymes.

scholarly journals Properties of PTFE tape as a semipermeable membrane in fluorous reactions

2015 ◽  
Vol 11 ◽  
pp. 980-993 ◽  
Author(s):  
Brendon A Parsons ◽  
Olivia Lin Smith ◽  
Myeong Chae ◽  
Veljko Dragojlovic
Keyword(s):  
Surface Tension ◽  
Organic Compounds ◽  
Polymer Films ◽  
Semipermeable Membrane ◽  
Reaction Vessel ◽  
Dimethyl Phthalate ◽  
Delivery Tube ◽  
Selective Permeability ◽  
Solvent Uptake ◽  
Solvent Adsorption

In a PTFE tape phase-vanishing reaction (PV-PTFE), a delivery tube sealed with PTFE tape is inserted into a vessel which contains the substrate. The reagent diffuses across the PTFE tape barrier into the reaction vessel. PTFE co-polymer films have been found to exhibit selective permeability towards organic compounds, which was affected by the presence of solvents. In this study, we attempted to establish general trends of permeability of PTFE tape to different compounds and to better describe the process of solvent transport in PV-PTFE bromination reactions. Though PTFE tape has been reported as impermeable to some compounds, such as dimethyl phthalate, solvent adsorption to the tape altered its permeability and allowed diffusion through channels of solvent within the PTFE tape. In this case, the solvent-filled pores of the PTFE tape are chemically more akin to the adsorbed solvent rather than to the PTFE fluorous structure. The solvent uptake effect, which was frequently observed in the course of PV-PTFE reactions, can be related to the surface tension of the solvent and the polarity of the solvent relative to the reagent. The lack of pores in bulk PTFE prevents solvents from altering its permeability and, therefore, bulk PTFE is impermeable to most solvents and reagents. However, bromine, which is soluble in liquid fluorous media, diffused through the bulk PTFE. A better understanding of the PTFE phase barrier will make it possible to further optimize the PV-PTFE reaction design.

Diffusion coefficients and viscosities of organic aerosol components through equilibrium and non-equilibrium molecular dynamics simulations

2021 ◽  
Author(s):  
Katerina S. Karadima ◽  
Vlasis G. Mavrantzas ◽  
Spyros N. Pandis
Keyword(s):  
Molecular Dynamics ◽  
Functional Groups ◽  
Organic Compounds ◽  
Diffusion Coefficients ◽  
Amorphous Solid ◽  
Good Effect ◽  
Hydroxyl Groups ◽  
Chemical Structures ◽  
Organic Particles ◽  
Non Equilibrium

<p>Organic aerosols have been typically considered to be liquid, with equilibration between gas and aerosol phase assumed to be reached within seconds. However, Virtanen et al. (Nature, 2010) suggested that particles in amorphous solid state may also occur in the atmosphere implying that mass transfer between the atmospheric particulate and gas phases may be much slower than initially thought. Experimentally, the direct measurement of the diffusion coefficients of different compounds inside atmospheric organic particles is challenging. Thus, an indirect approach is usually employed, involving viscosity measurements and then estimation of diffusion coefficients via the Stokes-Einstein equation, according to which the diffusion coefficient is inversely proportional to the medium viscosity. However, the corresponding diffusion estimates are highly uncertain, especially for highly viscous aerosols which is the most important case. Molecular simulation methods, such as molecular dynamics (MD), can be an alternative method to determine directly the diffusion rates and the viscosity of the constituents of atmospheric organic particles. MD also provides detailed information of the exact dynamics and motion of the molecules, thus offering a deeper understanding on the underlying mechanisms and interactions.</p><p>In the present work, we use equilibrium and non-equilibrium MD simulations to estimate the viscosity and diffusion coefficients of bulk systems of representative organic compounds with different chemical structures and physicochemical characteristics. Hydrophilic and hydrophobic compounds representative of primary and secondary oxidized organic products and of primary organic compounds emitted by various sources are considered. The viscosity and self-diffusion coefficients calculated by our simulations are in good agreement with available experimentally measured values. Our results confirm that the presence of carboxyl and hydroxyl groups in the molecule increases the viscosity. The number of carboxyl and hydroxyl groups, in particular, seems to have a good effect on diffusivity (the diffusivity decreases as the number of these functional groups increase), and to a lesser extent on the viscosity. We also discuss the role of the hydrogen bonds formed between these functional groups.</p>

Study on the Development and Performance of a New Concrete Antifoaming Agent

2021 ◽  
Vol 871 ◽  
pp. 357-362
Author(s):  
Ge Li Li ◽  
Yun Hui Fang ◽  
Chuan Deng Wu ◽  
You Zhe Shao ◽  
Yuan Qiang Guo ◽  
...  
Keyword(s):  
Surface Tension ◽  
Functional Groups ◽  
Gemini Surfactant ◽  
Water Solubility ◽  
Raw Materials ◽  
Mechanical Method ◽  
Silicone Surfactant ◽  
Silicone Surfactants ◽  
Antifoaming Agent ◽  
And Performance

Gemini surfactant acetylene glycol polyethers and polyhydrosilicone oil were used as raw materials to generate the acetylene glycol surfactants with defoaming, antifoaming properties, and polyether modification through a hydrolyzation reaction. A novel silicone surfactant based on acetylene glycol-modified polyoxysilane, which has the advantages of low surface tension and good water solubility. Its structure characterized by infrared. Finally, the new silicone surfactant prepared was emulsified with a composite emulsifier, and a new concrete defoamer was prepared by a mechanical method. The defoaming performance, foam suppression performance and surface tension were tested. The results showed that the new silicone surfactants contained functional groups of acetylene glycol and siloxane. The composite emulsifiers were Span40 and Tween60, which the HLB value was 10, the amount was 5% and the emulsification time was 30 minutes. The prepared new concrete defoamer has good defoaming and antifoaming properties with a low surface tension.

scholarly journals SURFACE TENSION OF SERUM

1922 ◽  
Vol 35 (5) ◽  
pp. 707-735 ◽  
Author(s):  
P. Lecomte du Noüy
Keyword(s):  
Surface Tension ◽  
Surface Layer ◽  
Free Surface ◽  
Organic Compounds ◽  
Sodium Oleate ◽  
Mean Value ◽  
Physiological Solution ◽  
Optimum Concentration ◽  
Initial Value ◽  
Ring Method

The application of the ring method to the measurement of solutions of serum and of certain organic compounds has brought forth new facts, mainly the decrease of the surface tension of such solutions in function of time. 1. In serum diluted at such a low concentration as 1:1,000,000 in NaCl, physiological solution, the surface tension of the liquid is lowered by 3 or 4 dynes in 2 hours; at 1:100,000, by about 11 dynes (mean value) in 2 hours, and by 20 dynes in 24 hours; at 1:10,000 by about 13 to 16 dynes in 2 hours. 2. The drop in surface tension is much more rapid in the first 30 minutes and follows generally the law of adsorption in the surface layer in function of the time. 3. Stirring or shaking after the drop causes the surface tension to rise, but generally below its initial value. 4. The same phenomena occur when using sodium oleate, glycocholate, or saponin instead of serum. 5. For every serum, as well as for the substances mentioned above a maximum drop occurs in certain conditions at a given optimum concentration. 6. Not only are the substances which lower the surface tension adsorbed in the surface layer, in the case in which they are present with crystalloids, but also the crystalloids themselves, in contradiction to Gibbs' statement. This is plainly shown by the evaporation of such solutions in watch-glasses which, instead of a small group of sharp, large, well defined crystals at the bottom, leaves a white disc almost as large as the initial free surface itself, due to the liberation of the salt by the surface layer as it crawls down the concave surface of the glass. 7. In these conditions, solutions of serum are characterized by a very peculiar periodic and concentric distribution of the crystals, at a concentration of 1:100 only. The same ring-like aspect is observed with sodium oleate, glycocholate, and saponin, but not at the same concentration, as was to be expected, since serum is a solution in itself.

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