Solvent Pairs
Solvent Pairs - Related Videos
01:12
Solvents
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2019
A solvent is a substance, most often a liquid, that can dissolve other substances. Here, the substance being dissolved is called a solute. When a solvent and a solute combine, they form a solution - a homogenous mixture of both the solvent and the solute. Water is a universal biological solvent. Its polar structure allows it to dissolve many other polar compounds. The ability of water to dissolve is governed by a balance between water molecules binding to each other and binding to the solute. A...
06:43
Rotary Evaporation to Remove Solvent
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2023
Source: Dr. Melanie Pribisko Yen and Grace Tang — California Institute of Technology Rotary evaporation is a technique most commonly used in organic chemistry to remove a solvent from a higher-boiling point compound of interest. The rotary evaporator, or "rotovap", was invented in 1950 by the chemist Lyman C. Craig. The primary use of a rotovap is to dry and purify samples for downstream applications. Its speed and ability to handle large volumes of solvent make rotary evaporation a preferred...
09:41
Schlenk Lines Transfer of Solvents
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2023
Source: Hsin-Chun Chiu and Tyler J. Morin, laboratory of Dr. Ian Tonks—University of Minnesota Twin Cities Schlenk lines and high vacuum lines are both used to exclude moisture and oxygen from reactions by running reactions under a slight overpressure of inert gas (usually N2 or Ar) or under vacuum. Vacuum transfer has been developed as a method separate solvents (other volatile reagents) from drying agents (or other nonvolatile agents) and dispense them to reaction or storage vessels while...
08:13
Preparation of Biopolymer Aerogels Using Green Solvents
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Cited by 44 •
2016
A new way for the production of biopolymer-based aerogels by carbon dioxide (CO2) induced gelation is shown. The technique utilizes pressurized carbon dioxide (5 MPa) for the production of biopolymer hydrogels and supercritical CO2 (12 MPa) to convert gels into aerogels. The only solvents needed besides CO2 are water and ethanol.
01:16
Titration in Nonaqueous Solvents
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2024
Most acid-base titrations are performed in an aqueous medium. In aqueous titrations, water competes with weaker acids or bases for proton donation or acceptance, leading to ambiguous endpoints in the titration curve. Water also affects the partial ionization of weak acids or bases. For example, water accepts a proton from acetic acid to form hydronium and acetate ions. The hydronium ion formed is a stronger acid than acetic acid, and the acetate ion is a stronger base than water. As a result,...
FAQs
Solvent-pair performance depends on balancing polarity, miscibility, boiling point, and temperature-dependent solubility. The primary solvent should dissolve the compound effectively under the chosen conditions, while the second changes the compound’s solubility without forming a separate liquid phase. This balance determines whether cooling or evaporation produces crystals rather than leaving the compound dissolved.
Miscibility keeps the liquids as one phase while their combined composition changes the target compound’s solubility. That allows the compound to dissolve in the more favorable solvent and then crystallize as cooling or evaporation lowers its solubility. If the liquids separated, the system would no longer provide the controlled, uniform environment needed for predictable crystallization.
A useful pair exploits a meaningful change in solubility with temperature. Heating can allow the target compound to enter solution, whereas cooling reduces its solubility and encourages crystal formation. Selection also requires checking compound stability, because conditions that improve dissolution or crystallization are unsuitable if the compound does not remain stable under those conditions.
They compare the target compound’s solubility in each liquid, the liquids’ miscibility, their polarity, boiling points, and the compound’s stability. They also consider whether temperature changes will produce the desired solubility shift. Together, these criteria indicate whether the pair can support purification and whether the solvents suit the planned crystallization conditions.
After a reaction, the pair can be selected so the desired solid responds differently from impurities to the solvent environment. The target is brought into solution under conditions that favor dissolution, then crystallization conditions are adjusted so the product forms crystals while impurities remain dissolved or separate. This improves isolation and chemical purity.
Comparing solvent pairs shows how solvent polarity, miscibility, boiling point, and solubility changes affect crystal formation. A successful combination provides evidence that the target can be dissolved and later recovered as crystals under suitable conditions. This comparison helps chemists optimize crystallization rather than relying on a single solvent choice for every compound.