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a)
Interpretation:Solution recrystallization should be defined.
Concept introduction: Sublimation, extraction and chromatography are methods that are used for purification of organic compounds. But recrystallization involves isolation of compounds with extremely high purity. Recrystallization is one of techniques that are employed to purify organic compounds.
a)
Explanation of Solution
Solution recrystallization or simply recrystallization is technique that is used for purification of organic compounds. This process includes dissolution of solid in specific solvent at high temperature and then crystals are made again by process of cooling. Temperature of crystals is decreased to allow impurities to remain in solution only.
b)
Interpretation:Temperature coefficient of solvent should be defined.
Concept introduction:Recrystallization is technique that is used for purification of organic compounds. This process includes dissolution of solid in specific solvent at high temperature and then crystals are made again by process of cooling. Temperature of crystals is decreased to allow impurities to remain in solution only.
b)
Explanation of Solution
Recrystallization solvent should be chosen in such way that compound is insoluble at low temperatures but becomes soluble at high temperatures. This variance in solubility of compound is governed by temperature coefficient of solvent.
c)
Interpretation:Relationship between dielectric constant and polarity of solvent should be defined.
Concept introduction:Recrystallization is technique that is used for purification of organic compounds. This process includes dissolution of solid in specific solvent at high temperature and then crystals are made again by process of cooling. Temperature of crystals is decreased to allow impurities to remain in solution only.
c)
Explanation of Solution
Most commonly used solvents for recrystallization varies widely in terms of their polarities. These polarities are measured by respective dielectric constants. Solvents with dielectric constants from 2 to 3 are nonpolar while those with values of dielectric constants more than 10 are polar. Solvents with dielectric constant in range of 3 to 10 are considered as intermediate polar. Polar compounds are usually soluble in polar solvents and vice-versa. So polarity of solvent is directly related to dielectric constant.
d)
Interpretation:Petroleum ether should be defined.
Concept introduction: Recrystallization is technique that is used for purification of organic compounds. This process includes dissolution of solid in specific solvent at high temperature and then crystals are made again by process of cooling. Temperature of crystals is decreased to allow impurities to remain in solution only.
d)
Explanation of Solution
Petroleum ether is generally used as solvent in recrystallization process. It is flammable and highly volatile in nature. It is also known as benzene. Chemical structure for petroleum ether does not contain ether
e)
Interpretation:Mixed solvents should be defined.
Concept introduction:Recrystallization is technique that is used for purification of organic compounds. This process includes dissolution of solid in specific solvent at high temperature and then crystals are made again by process of cooling. Temperature of crystals is decreased to allow impurities to remain in solution only.
e)
Explanation of Solution
If more than one solvent exists in mixture, it is termed as mixed solvent. So mixed solvents are usually made up of two or more types of single solvents. For example, isoamyl or banana oil is mixed solvent.
f)
Interpretation:Solvent selection should be defined.
Concept introduction: Recrystallization is technique that is used for purification of organic compounds. This process includes dissolution of solid in specific solvent at high temperature and then crystals are made again by process of cooling. Temperature of crystals is decreased to allow impurities to remain in solution only.
f)
Explanation of Solution
Criteria mentioned below should be used to select solvent for recrystallization.
1. Solvent should be able to dissolve desired compound in itself at high temperatures but insoluble at low temperatures. In short, solvent with favorable temperature coefficient should be used for particular solute.
2. Solvent should be chosen in such way that impurities are either insoluble in it or remain moderately soluble in it at low temperatures.
3. Boiling point of desired solvent should be low so that it gets separated from crystals easily.
4. Boiling point of solvent should be less than melting point of solid under consideration.
5. There should be no reaction between solvent and substance that needs to be purified.
g)
Interpretation:Filter-aid should be defined.
Concept introduction:Recrystallization is technique that is used for purification of organic compounds. This process includes dissolution of solid in specific solvent at high temperature and then crystals are made again by process of cooling. Temperature of crystals is decreased to allow impurities to remain in solution only.
g)
Explanation of Solution
Filter aid is substance or agent that is composed of solid particles and is used to improve efficiency of filtration. Its use also controls flow of liquids and removal of solid particles.
h)
Interpretation:Hot filtration should be defined.
Concept introduction: Recrystallization is technique that is used for purification of organic compounds. This process includes dissolution of solid in specific solvent at high temperature and then crystals are made again by process of cooling. Temperature of crystals is decreased to allow impurities to remain in solution only.
h)
Explanation of Solution
Hot filtration is technique that is used in recrystallization process when insoluble solid impurities are present in solvent. This process is essential to follow when activated charcoal is used to remove colored impurities in recrystallization process.
i)
Interpretation:Seeding should be defined.
Concept introduction:Recrystallization is technique that is used for purification of organic compounds. This process includes dissolution of solid in specific solvent at high temperature and then crystals are made again by process of cooling. Temperature of crystals is decreased to allow impurities to remain in solution only.
i)
Explanation of Solution
Seeding is method that is used to control supersaturation. Supersaturated solutions are allowed to form crystals by process of seeding. Any of crystals formed are added to solution to induce crystallization that occurs on rapid pace.
j)
Interpretation:Vacuum filtration should be defined.
Concept introduction: Recrystallization is technique that is used for purification of organic compounds. This process includes dissolution of solid in specific solvent at high temperature and then crystals are made again by process of cooling. Temperature of crystals is decreased to allow impurities to remain in solution only.
j)
Explanation of Solution
Vacuum filtration is technique that is applied to separate solid products from liquids. It is performed with help of Buchner funnel that is attached to vacuum filter flask with aid of rubber stopper or neoprene adapter. Side arm of filter flask is attached to house vacuum line through trap called filter trap. This trap is used for collection of overflowed filtrate from filter flask.
k)
Interpretation:Mother liquor should be defined.
Concept introduction:Recrystallization is technique that is used for purification of organic compounds. This process includes dissolution of solid in specific solvent at high temperature and then crystals are made again by process of cooling. Temperature of crystals is decreased to allow impurities to remain in solution only.
k)
Explanation of Solution
Mother liquor is nothing but part of solution that remains after crystallization of pure compound. This liquid is generally obtained in filtration process.
l)
Interpretation:Filtrate should be defined.
Concept introduction: Recrystallization is technique that is used for purification of organic compounds. This process includes dissolution of solid in specific solvent at high temperature and then crystals are made again by process of cooling. Temperature of crystals is decreased to allow impurities to remain in solution only.
l)
Explanation of Solution
Filtration is procedure that is used to remove insoluble impurities, decolorized activated carbon from solution and also for purification of compound. Liquid that has been passed through filter apparatus is called filtrate while solid that cannot pass through filter is known as residue.
m)
Interpretation: Solute should be defined.
Concept introduction: Recrystallization is technique that is used for purification of organic compounds. This process includes dissolution of solid in specific solvent at high temperature and then crystals are made again by process of cooling. Temperature of crystals is decreased to allow impurities to remain in solution only.
m)
Explanation of Solution
Solution always has two components, one is solute and another is solvent. Solute is that part of solution that is present in small quantity and that dissolves itself into another component called solvent. So solvent is present in larger amount in solution and it dissolves solute in itself.
n)
Interpretation: Solvent should be defined.
Concept introduction: Recrystallization is technique that is used for purification of organic compounds. This process includes dissolution of solid in specific solvent at high temperature and then crystals are made again by process of cooling. Temperature of crystals is decreased to allow impurities to remain in solution only.
n)
Explanation of Solution
Solution always has two components, one is solute and another is solvent. Solute is that part of solution that is present in small quantity and that dissolves itself into another component called solvent. So solvent is present in larger amount in solution and it dissolves solute in itself.
o)
Interpretation:Occlusion should be defined.
Concept introduction: Recrystallization is technique that is used for purification of organic compounds. This process includes dissolution of solid in specific solvent at high temperature and then crystals are made again by process of cooling. Temperature of crystals is decreased to allow impurities to remain in solution only.
o)
Explanation of Solution
Occlusion occurs when one substance is included into another one. This process usually occurs if crystallization or precipitation occurs at high speeds.
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Chapter 3 Solutions
OWLv2 with LabSkills for Gilbert/Martin's Experimental Organic Chemistry: A Miniscale & Microscale Approach, 6th Edition, [Instant Access], 4 terms (24 months)
- 111 Carbonyl Chem Choosing reagants for a Wittig reaction What would be the best choices for the missing reagents 1 and 3 in this synthesis? 1. PPh3 3 1 2 2. n-BuLi • Draw the missing reagents in the drawing area below. You can draw them in any arrangement you like. Do not draw the missing reagent 2. If you draw 1 correctly, we'll know what it is. • Note: if one of your reagents needs to contain a halogen, use bromine. Explanation Check Click and drag to start drawing a structure. × ©2025 McGraw Hill LLC. All Rights Reserved. Terms of Usearrow_forwardA student proposes the transformation below in one step of an organic synthesis. There may be one or more reactants missing from the left-hand side, but there are no products missing from the right-hand side. There may also be catalysts, small inorganic reagents, and other important reaction conditions missing from the arrow. • Is the student's transformation possible? If not, check the box under the drawing area. . If the student's transformation is possible, then complete the reaction by adding any missing reactants to the left-hand side, and adding required catalysts, inorganic reagents, or other important reaction conditions above and below the arrow. • You do not need to balance the reaction, but be sure every important organic reactant or product is shown. + T X O O лет-ле HO OH HO OH This transformation can't be done in one step.arrow_forwardDetermine the structures of the missing organic molecules in the following reaction: X+H₂O H* H+ Y OH OH Note: Molecules that share the same letter have the exact same structure. In the drawing area below, draw the skeletal ("line") structures of the missing organic molecules X and Y. You may draw the structures in any arrangement that you like, so long as they aren't touching. Click and drag to start drawing a structure. X Sarrow_forward
- Predict the major products of this organic reaction. If there aren't any products, because nothing will happen, check the box under the drawing area instead. No reaction. HO. O :☐ + G Na O.H Click and drag to start drawing a structure. XS xs H₂Oarrow_forwardWhat are the angles a and b in the actual molecule of which this is a Lewis structure? H H C H- a -H b H Note for advanced students: give the ideal angles, and don't worry about small differences from the ideal groups may have slightly different sizes. a = b = 0 °arrow_forwardWhat are the angles a and b in the actual molecule of which this is a Lewis structure? :0: HCOH a Note for advanced students: give the ideal angles, and don't worry about small differences from the ideal that might be caused by the fact that different electron groups may have slightly different sizes. a = 0 b=0° Sarrow_forward
- Determine the structures of the missing organic molecules in the following reaction: + H₂O +H OH O OH +H OH X Note: Molecules that share the same letter have the exact same structure. In the drawing area below, draw the skeletal ("line") structure of the missing organic molecule X. Click and drag to start drawing a structure.arrow_forwardIdentify the missing organic reactant in the following reaction: x + x O OH H* + ☑- X H+ O O Х Note: This chemical equation only focuses on the important organic molecules in the reaction. Additional inorganic or small-molecule reactants or products (like H₂O) are not shown. In the drawing area below, draw the skeletal ("line") structure of the missing organic reactant X. Click and drag to start drawing a structure. Carrow_forwardCH3O OH OH O hemiacetal O acetal O neither O 0 O hemiacetal acetal neither OH hemiacetal O acetal O neither CH2 O-CH2-CH3 CH3-C-OH O hemiacetal O acetal CH3-CH2-CH2-0-c-O-CH2-CH2-CH3 O neither HO-CH2 ? 000 Ar Barrow_forward
- What would be the best choices for the missing reagents 1 and 3 in this synthesis? 1. PPh3 2 2. n-BuLi 3 Draw the missing reagents in the drawing area below. You can draw them in any arrangement you like. • Do not draw the missing reagent 2. If you draw 1 correctly, we'll know what it is. • Note: if one of your reagents needs to contain a halogen, use bromine. Explanation Check Click and drag to start drawing a structure.arrow_forwardPredict the products of this organic reaction: NaBH3CN + NH2 ? H+ Click and drag to start drawing a structure. ×arrow_forwardPredict the organic products that form in the reaction below: + OH +H H+ ➤ ☑ X - Y Note: You may assume you have an excess of either reactant if the reaction requires more than one of those molecules to form the products. In the drawing area below, draw the skeletal ("line") structures of the missing organic products X and Y. You may draw the structures in any arrangement that you like, so long as they aren't touching. Click and drag to start drawing a structure. Garrow_forward
Macroscale and Microscale Organic ExperimentsChemistryISBN:9781305577190Author:Kenneth L. Williamson, Katherine M. MastersPublisher:Brooks Cole