Related Experiment Video
Updated: Feb 26, 2026
06:44
From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding
Published on: March 24, 2018
69.7K
Hydrophilicity controls thermodiffusion in alkylammonium chlorides
Binny A Rudani1, Hartmut Kriegs1, Simone Wiegand2,3
1IBI-4, Research center Juelich, 52425, Juelich, Germany.
The European Physical Journal. E, Soft Matter
|February 24, 2026
Summary
The Soret coefficient of ammonium chloride and its alkyl-substituted derivatives increases with alkylation and temperature, indicating reduced hydrophilicity and altered thermal transport in aqueous solutions.
Area of Science:
- Physical Chemistry
- Solution Chemistry
- Transport Phenomena
Background:
- The Soret effect describes the thermodiffusion of solutes in a solution under a temperature gradient.
- Understanding ion-specific interactions and hydrophilicity is crucial for predicting molecular transport in aqueous systems.
Purpose of the Study:
- To investigate the Soret effect of ammonium chloride and its alkyl-substituted derivatives (DMACl, EACl, TMACl) in aqueous solutions.
- To determine how alkyl substitution and temperature influence the Soret coefficient and hydrophilicity.
- To explore the relationship between thermal diffusion, thermal expansion, and ion-specific interactions.
Main Methods:
- Utilized infrared thermal diffusion forced Rayleigh scattering to measure the Soret coefficient (S_T).
- Examined a temperature range of 15-45°C and concentrations of 1-4 mol/kg.
- Analyzed the concentration and temperature dependence of S_T for various ammonium chloride derivatives.
Main Results:
- Soret coefficient systematically increases with alkyl substitution (NH4Cl << DMACl < EACl << TMACl), correlating with decreased hydrophilicity.
- S_T increases with temperature and alkyl substitution, but concentration dependence varies among salts.
- Ammonium chloride exhibits thermophilic behavior with non-monotonic concentration dependence at higher temperatures, while derivatives are predominantly thermophobic.
- A correlation was observed between the thermal diffusion coefficient and thermal expansion coefficient in these electrolyte solutions.
Conclusions:
- Alkyl substitution significantly impacts thermodiffusion behavior in aqueous electrolyte solutions, reducing temperature sensitivity and hydrophilicity.
- Thermodiffusion serves as a sensitive method for probing hydrophilicity and ion-specific effects on molecular transport.
- Observed correlations align with trends in nonpolar mixtures and non-ionic solutes, suggesting general principles in thermal transport.
Related Concept Videos
02:45Alkyl Halides
20.6K
Structural Properties
Alkyl halides are halogen-substituted alkanes wherein one or more hydrogen atoms of an alkane is replaced by a halogen atom such as fluorine, chlorine, bromine, or iodine. The carbon atom in an alkyl halide is bonded to the halogen atom, which is sp3-hybridized and exhibits a tetrahedral shape.
Unlike alkyl halides, compounds in which a halogen atom is bonded to an sp2 -hybridized carbon atom of a carbon-carbon double bond (C=C) are called vinyl halides. Whereas aryl...
Alkyl halides are halogen-substituted alkanes wherein one or more hydrogen atoms of an alkane is replaced by a halogen atom such as fluorine, chlorine, bromine, or iodine. The carbon atom in an alkyl halide is bonded to the halogen atom, which is sp3-hybridized and exhibits a tetrahedral shape.
Unlike alkyl halides, compounds in which a halogen atom is bonded to an sp2 -hybridized carbon atom of a carbon-carbon double bond (C=C) are called vinyl halides. Whereas aryl...
20.6K
02:35Electrophilic Addition to Alkynes: Hydrohalogenation
11.6K
Electrophilic addition of hydrogen halides, HX (X = Cl, Br or I) to alkenes forms alkyl halides as per Markovnikov's rule, where the hydrogen gets added to the less substituted carbon of the double bond. Hydrohalogenation of alkynes takes place in a similar manner, with the first addition of HX forming a vinyl halide and the second giving a geminal dihalide.
11.6K
02:17Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
17.8K
If a set of reactants can yield multiple constitutional isomers, but one of the isomers is obtained as the major product, the reaction is said to be regioselective. In such reactions, bond formation or breaking is favored at one reaction site over others.
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
17.8K
02:34Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
9.8K
The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.
9.8K
02:41Formation of Halohydrin from Alkenes
14.9K
An alkene, such as propene, reacts with bromine in the presence of water to yield a halohydrin. Halohydrins contain a halogen and a hydroxyl group attached to adjacent carbons. When the halogen is bromine, it is called a bromohydrin, while a chlorohydrin has chlorine as the halogen.
14.9K
01:23Electrophilic Addition of HX to 1,3-Butadiene: Thermodynamic vs Kinetic Control
4.3K
The addition of a hydrogen halide to 1,3-butadiene gives a mixture of 1,2- and 1,4-adducts. Since more substituted alkenes are more stable, the 1,4-adduct is expected to be the major product. However, the product distribution is strongly influenced by temperature; low temperature favors the 1,2-adduct, whereas the 1,4-adduct is predominant at high temperature.
4.3K