Recrystallization Purification
Recrystallization Purification - Related Videos
09:58
Purifying Compounds by Recrystallization
0 Views •
2023
Source: Laboratory of Dr. Jimmy Franco - Merrimack College Recrystallization is a technique used to purify solid compounds.1 Solids tend to be more soluble in hot liquids than in cold liquids. During recrystallization, an impure solid compound is dissolved in a hot liquid until the solution is saturated, and then the liquid is allowed to cool.2 The compound should then form relatively pure crystals. Ideally, any impurities that are present will remain in the solution and will not be...
03:12
Recrystallization - Concepts
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2020
Recrystallization Often, the desired product of a chemical reaction is part of a more complex reaction mixture, which can be composed of the solvent, starting materials, and impurities. Learning how to purify organic compounds properly is a valuable technique in organic chemistry. Recrystallization harnesses the differences in solubility of the desired compound and the impurity in the solvent to purify the desired product as a solid. There are three standard methods of purification:...
13:15
Recrystallization - Student Protocol
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2020
Source: Lara Al Hariri and Ahmed Basabrain at the University of Massachusetts Amherst, MA, USA Recrystallization of AcetanilideExpand In this part of the lab, you'll purify acetanilide by recrystallization from an aqueous solution. Acetanilide is moderately soluble in boiling water, but it's much less soluble in room temperature and cold water. Aniline, a potential impurity, is much more soluble in room temperature water. Thus, you'll first make a saturated solution of acetanilide in boiling...
03:03
Recrystallization - Instructor Prep
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2020
Source: Lara Al Hariri at the University of Massachusetts Amherst, MA, USA Preparation of the LaboratoryExpand Here, we show the laboratory preparation for 10 students working in pairs, with some excess. Please adjust quantities as needed. To set up for this lab experiment, wear the appropriate personal protective equipment, including a lab coat, chemical splash goggles, and gloves. Confirm that the lab has a glass waste container and a container for solid acetanilide and...
09:43
Identification of Plant Ice-binding Proteins Through Assessment of Ice-recrystallization Inhibition and Isolation Using Ice-affinity Purification
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Cited by 5 •
2017
This paper outlines the identification of ice-binding proteins from freeze-tolerant plants through the assessment of ice-recrystallization inhibition activity and subsequent isolation of native IBPs using ice-affinity purification.
FAQs
The solvent should dissolve the target compound readily at elevated temperature but poorly at lower temperature. This contrast allows the compound to enter solution during heating and then form crystals during cooling. A suitable solvent also helps separate soluble impurities, which remain in the liquid phase, from insoluble materials that can be removed before crystallization.
Soluble impurities can remain in the mother liquor because they stay dissolved as the target compound crystallizes. Insoluble impurities follow a different pathway: they do not enter solution and can be removed through hot filtration. This separation depends on the impurities' solubility behavior relative to the target compound and the selected solvent.
Using the minimum solvent volume needed to dissolve the heated solid generally supports better recovery because less target compound remains dissolved after cooling. Excess solvent can reduce the amount that crystallizes, whereas too little may prevent complete dissolution. The solvent amount therefore influences both the efficiency of purification and the quantity recovered.
The impure solid is first combined with a selected solvent and heated until the target compound dissolves. If insoluble material is present, the hot solution is filtered. The clarified solution is then allowed to cool so crystals form, while soluble impurities remain in the mother liquor. This sequence separates the target from different impurity classes.
Hot filtration is useful when the starting solid contains material that does not dissolve in the hot solvent. Filtering while the solution remains hot removes those insoluble particles before they can become trapped in the developing crystals. The step preserves the separation between insoluble contaminants and the dissolved target compound.
Purified crystals can support melting-point analysis, spectroscopy, synthesis, and later experiments. Removing impurities is especially important when a compound's physical or spectroscopic properties will be examined, because the resulting material more closely represents the target substance. Recrystallization therefore serves both as a cleanup step and as preparation for chemical characterization.