Name: moisture-free setup for organic reactions
Uploaded: 2023-04-30T06:47:26.000Z
Duration: 10 min 17 s
Channel: JoVE

K12 Standards

new-york-state-science-learning-standards

New York State Science Learning Standards

High School

Physical Science

HS. Structure and Properties of Matter

HS-PS1-10.

preparing-anhydrous-reagents-and-equipment

Preparing Anhydrous Reagents and Equipment

Drying of Glassware
1. Oven-Drying
<ol>
	<li>Remove all pieces that are not made of glass, such as the stopcock of an addition funnel.</li>
	<li>Place all glassware that are part of the apparatus in a drying-oven set to about 125 &#176;C for at least 24 h before use.</li>
	<li>Put on heat protection gloves and remove glassware from the oven. Be very careful when handling hot glass while assembling the apparatus.</li>
	<li>For best results flush the apparatus with an inert gas such as N2&#160;while assembling the apparatus.</li>
</ol>
2. Flame-Drying
<ol>
	<li>Set up the full apparatus but remove all components that are not made of glass (such as stopcocks of dropping funnels or rubber sleeves etc.). Do not attach any tubing to the apparatus at this point.</li>
	<li>Put on heat-protection gloves.</li>
	<li>Set up a Bunsen burner and carefully flame-dry the apparatus. Start from the bottom and move the flame upward, &#34;accompanying&#34; the water on its way out. Steam will develop and fog up the glassware. Continue flame-drying until fogging stops.</li>
	<li>Wait for the apparatus to cool down to about 60 &#176;C. This takes a couple of minutes and the glass will still be warm to the touch but won&#39;t cause burns if contact is short.</li>
	<li>Carefully add the rest of the apparatus that is not made of glass, such as tubing and stopcocks. Do not remove heat-protection gloves when handling the apparatus to avoid burns.</li>
	<li>After everything is properly assembled, flush the apparatus with an inert gas such as N2to accelerate cooling of the glassware to a point where the reagents may be added.</li>
</ol>
Note: During the flame-drying process never have any solvent or the magnetic stir-bar inside the flask nor any of the reagents unless specifically demanded by the procedure. (However, when performing the Grignard reaction it is okay to leave the magnesium shavings in the flask during flame-drying).
3. Drying with Acetone
<ol>
	<li>Rinse glassware with acetone.</li>
	<li>Collect the acetone rinsings in a designated solvent waste container.</li>
	<li>Flush the glassware with N2 gas or dry compressed air to accelerate drying.</li>
</ol>
Drying of Solvents
1. Drying with Active Sodium Metal
<ol>
	<li>Carefully cut sodium metal under petroleum ether to minimize the risk of ignition as the metal reacts with air. The metal surface oxidizes quickly giving a white residue. Cut the metal into thin slices exposing as much metallic surface area as possible.</li>
	<li>Under N2 gas add the metal shavings to a distillation flask containing solvent.</li>
	<li>Next add benzophenone, an indicator that is used to monitor the reaction. In the presence of water the solution is clear or yellow, but when the solvent is dry the solution is blue or purple.</li>
	<li>Reflux the solution using a heating mantle until a change of coloration to blue/purple is observed.</li>
	<li>Distill the solvent, collect it in a dry flask, and use in a reaction immediately after cooling down. 
	Waste Disposal: After the drying process it is important to safely dispose of any remaining sodium in the distillation flask.</li>
	<li>For this, carefully add ethanol to the sodium until hydrogen evolution has ceased.</li>
	<li>Stir the solution carefully, but well, and make sure that no sodium lumps remain that might have active sodium metal trapped inside.</li>
	<li>Carefully add methanol to the mixture and leave the mixture in the back of the hood for several hours to make sure the sodium is completely consumed.</li>
	<li>Finally, add the mixture very carefully to a large excess of water and dispose of the mixture in an appropriate waste disposal container.</li>
</ol>
2. Drying over Molecular Sieves
<ol>
	<li>Open a bottle containing molecular sieves and fill them into a thermo-stable glass beaker. Dry more than needed for the current experiment for future use.</li>
	<li>For activation place the beaker with the beads in a high temperature oven and store for 3&#8211;3.5 h at a temperature of 300&#8211;350 &#176;C. Alternatively, if available, store for in a vacuum oven at 200 &#176;C for the same amount of time.</li>
	<li>Using high heat-resistant gloves remove the beaker with the beads and place it in a conventional drying oven at temperatures above 120 &#176;C. Alternatively store the beaker with the beads inside of a desiccator. The beads may be stored for weeks before use.</li>
	<li>Remove the beaker with the beads from the drying oven or the desiccator. Work fast from this point onward to minimize contact of the beads with atmospheric water.</li>
	<li>If removing the beads from an oven allow them to cool down to about room temperature. Cover the beaker with a dry towel to minimize air exposure during this cooling time.</li>
	<li>To test whether the beads are still active, put on disposable gloves and place a small amount of beads in your hand. Add about 2 volume equivalents of water. If the beads become very hot then it means they are activated.</li>
	<li>Weigh off the needed amount of active beads on a scale. For example, to achieve a 10% m/v of beads in a 500-mL bottle of solvent, 50 g of beads are required.</li>
	<li>Add the room-temperature beads to a freshly opened bottle of solvent. Be certain that the beads are cooled, especially if the solvent is volatile. Never add the beads to a solvent directly after removing them from the oven.</li>
	<li>For a volatile solvent, such as DCM, leave the lid on top of the bottle but wait a few minutes before fully screwing the lid on the bottle to avoid pressure build-up.</li>
	<li>Seal the area around the lid by wrapping it with Parafilm to keep moisture out.</li>
	<li>Store the solvent over the beads for the appropriate amount of time, for example 24 h.</li>
</ol>
Drying of Reagents
1. Drying of the Organic Phase after Extraction
<ol>
	<li>Upon separation of the phases in a separatory funnel, transfer the organic phase into a dry glass container, such as a beaker or Erlenmeyer flask (or a test tube for small scales).</li>
	<li>Add a drying agent from Table 2 (usually NaSO4or MgSO4) to the organic phase using a spatula. Initially the drying agent clumps together.</li>
	<li>Continue the addition until freshly added drying agent does not clump together and rolls about freely. Moreover, the solution should be clear and not cloudy.</li>
	<li>If available, cover the glass container with a stopper, otherwise with some aluminum foil.</li>
	<li>Allow the solution to stand for about 1 h over the drying agent. It is okay to allow it to stand for longer periods of time, for example over-night.</li>
	<li>Assemble a vacuum-filtration apparatus with B&#252;chner funnel and side-arm flask.</li>
	<li>Add a filter paper to the B&#252;chner funnel and turn on the vacuum.</li>
	<li>Slowly decant off the organic phase into the B&#252;chner funnel. Initially, try not to transfer any of the drying agent or the filter will clog.</li>
	<li>When most of the liquid has been transferred onto the funnel and drained into the flask below, add the remainder of the organic phase together with the drying agent and allow to stand for a few minutes.</li>
	<li>Turn off the vacuum and transfer the organic phase into a dry round bottom flask.</li>
	<li>Connect the round-bottom flask to a rotary evaporator and remove all solvent under reduced pressure.</li>
	<li>If the product is a liquid, store it over a drying agent and freshly distill it before use.</li>
</ol>
2. Drying of Solid Reagents
<ol>
	<li>Place the solid reagent inside an open glass container and determine the combined weight.</li>
	<li>Place the container with the reagent into a drying oven set to a temperature below the melting point of the solid. When available, use a vacuum oven. Use heat protection gloves if necessary.</li>
	<li>Allow the reagent to dry for several hours inside the oven.</li>
	<li>Remove the container with the reagent from the oven.</li>
	<li>Allow the sample to cool to room temperature, ideally inside of a desiccator.</li>
	<li>Determine the weight and ensure that it is lower than before drying. If necessary repeat steps 2.2 &#8211; 2.5.</li>
	<li>Once the reagent is cooled to room temperature it is ready for use.</li>
	<li>If the reagent does not need to be used immediately, flush the container with an inert gas, such as N2 and seal it tightly with a lid and place Parafilm around the lid.</li>
	<li>Place the container inside a desiccator and store it there until the reagent is needed.</li>
</ol>
3. Drying of Heat-Sensitive Solid Reagents
<ol>
	<li>Prepare a desiccator by placing fresh anhydrous drying agent in the lower compartment (typically P2O5).</li>
	<li>Place the solid reagent inside an open glass container and determine its weight.</li>
	<li>Place the container with the reagent it inside a desiccator.</li>
	<li>Close the lid of the desiccator, sliding it on horizontally from the side to ensure proper sealing.</li>
	<li>Apply a vacuum to the desiccator using the stopcock connection.</li>
	<li>After a few minutes close the stopcock and turn off the vacuum.</li>
	<li>Allow the reagent to dry inside the desiccator for at least a few hours.</li>
	<li>Open the stopcock on the desiccator and allow air to flow in.</li>
	<li>Carefully slide off the lid of the desiccator horizontally. Do not attempt to pull the lid off vertically.</li>
	<li>Remove the reagent from the desiccator and weigh it. It should have a lower weight than before it was dried.</li>
	<li>If necessary repeat steps 3.3 &#8211; 3.10 until the weight remains stable and the reagent is fully dry.</li>
	<li>If the reagent does not need to be used immediately, flush the container with an inert gas&#160;such as N2&#160;and seal it tightly with a lid and place Parafilm around the lid.</li>
	<li>Place the container inside a desiccator and store it there until the reagent is needed.</li>
</ol>

preparing anhydrous reagents and equipment

Source: Laboratory of Dr. Dana Lashley - College of William and Mary 
Demonstrated by: Timothy Beck and Lucas Arney
Many reactions in organic chemistry are moisture-sensitive and must be carried out under careful exclusion of water. In these cases the reagents have a high affinity to react with water from the atmosphere and if left exposed the desired reaction will not take place or give poor yields, because the reactants are chemically altered.
In order to prevent undesired reactions with H2O these reactions have to be carried out under an inert atmosphere. An inert atmosphere is generated by running the reaction under nitrogen gas, or in more sensitive cases, under a noble gas such as argon.
Every component in such a reaction must be completely anhydrous, or free of water. This includes all reagents and solvents used as well as all glassware and equipment that will come into contact with the reagents. Extremely water-sensitive reactions must be carried out inside of a glovebox which provides a completely sealed off anhydrous environment to work under via a pair of gloves which protrudes out to one of the sides of the chamber.

A classical example for a reaction that must be done under anhydrous conditions is the Grignard reaction. (Equation 1)
<img alt="Grignard reaction mechanism diagram: diethyl ether, quenching, ketone to alcohol conversion." src="/files/ftp_upload/10227/10227eq1.jpg" data-altupdatedat="1761830439000" data-alt="Equation">
In the first ste...

Source: Laboratory of Dr. Dana Lashley - College of William and Mary
Demonstrated by: Timothy Beck and Lucas Arney
Many reactions in organic chemistry are ...

Chemical reactions that are moisture-sensitive must be carried out in an anhydrous,?or water free,?environment.Reagents and reactants can sometimes react with or absorb water from the atmosphere. If this happens, the chemical or physical properties of the reagents can change, and the desired reaction will not take place or lead to a poor yield.To prevent undesired reactions with water from occurring?sensitive reactions are carried out under an inert atmosphere, such as nitrogen or argon, using anhydrous reagents and equipment. Extremely water-sensitive reactions must be carried out inside a glovebox that can maintain an anhydrous environment. This video will demonstrate how to properly dry glassware, solvents, and reagents in order to run an anhydrous reaction.The chemical makeup of glass causes a film of water to coat the surface that must be removed before preparing an anhydrous reaction. Heat or acetone is often used to remove this layer from clean glassware before use.Many solvents also absorb water from the environment and must be dried before use. Solvent stills or desiccants are often used to remove water prior to setting up a reaction.Solvent stills use alkali metals such as sodium to react with water?and leave a residual water content of around 10 parts per million.Desiccants are highly hygroscopic solids, meaning they readily absorb water. Certain desiccants, like sodium sulfate, are used to remove water from small amounts of an organic solvent and must be filtered out before further use.Molecular sieves are the most commonly used desiccant and are used to dry larger volumes of solvents. They are made from a microporous material composed of sodium and calcium aluminosilicates.Molecular sieves work by trapping water inside the beads?effectively removing it from the solvent. Once used?they can be regenerated in an oven.Finally, there are multiple ways to dry solid reagents. One is by storing it in an oven set 15?20 ?C below its melting point. The heat drives water from the reagent?leaving behind a dry compound.If the solid can't be heated or has too low of a melting point?it can be dried in a vacuum desiccator. Once dry, the anhydrous reagent can be stored in a bottle under an inert atmosphere inside the desiccator.Now that you've seen the concepts behind drying the equipment and reagents for anhydrous reactions, let's take a closer look and see how it's done in the laboratory.To dry glassware in an oven, first gather all the required components for the reaction apparatus. Remove all pieces not made of glass?such as the stopcock of a Schlenk flask.Place the glassware in a drying-oven set to 125 ?C and bake for at least 24 h before use.After 24 h, put on heat protection gloves and remove the glassware from the oven. Assemble the apparatus while the glassware is still hot.When the glassware is fully assembled and cool, flush the apparatus with an inert gas such as nitrogen. Finally, add back any pieces that were removed prior to drying. The glassware is now ready for the anhydrous reaction.A faster option than oven drying glassware is to use a Bunsen burner. Certain glassware shouldn't be flame dried, so make sure the setup is safe to flame dry before starting. To begin, set up the full apparatus and remove all components that are not made of glass.Put on heat resistant gloves, then light the Bunsen burner. Begin flame drying the glassware by heating the bottom of the apparatus. Drive the water out of the setup by moving the flame upward. Continue this process until fogging and steaming stops.Wait for the apparatus to cool down to about 60 ?C, then use heat resistant gloves and add the rest of the apparatus that was removed before flame drying.To dry solvents using molecular sieves, first add them into a thermo-stable glass container.The sieves must first be dried for proper operation, so place the container in a 300 to 350 ?C oven and bake for 3 ??3 ? h.When the beads are dry, use high heat-resistant gloves to remove the container and store it in a drying oven at temperatures above 120??C. After drying, the molecular sieves may be stored for weeks before use.When they are needed, remove the beads from the drying oven or desiccator. Work fast and cover the container from this point onward to minimize contact of the beads with atmospheric water.If removing the beads from an oven?allow them to cool down to roughly room temperature.Weigh out the necessary amount of active beads on a scale. For example, to achieve a 10% mass to volume of beads in a 500?mL bottle of solvent, 50 g of beads are required.Add the beads to the solvent. For a volatile solvent, such as dichloromethane, leave the lid on top of the bottle but wait a few minutes before fully screwing the lid on to avoid pressure build-up.Seal the area around the lid by wrapping it with Parafilm to keep moisture out. Store the solvent with the beads for at least 24 h. Afterward, the anhydrous solvent can be used in a reaction.Alternatively, solvent stills using sodium metal and benzophenone can be used to dry solvents.Solid reagents are often dissolved in organic solvents. Before removing the liquid and recovering the solid reagent?excess water must be removed from the solution.Obtain a dry container and add the solution. Next, add a drying agent to the container using a spatula. The drying agent will initially clump together, but continue adding until freshly added drying agent no longer clumps and moves freely.Cover the container with a stopper or aluminum foil and allow the solution to sit for at least 1 h.To remove the excess drying agent, assemble a vacuum-filtration apparatus with a B?chner funnel and side-arm flask. Add filter paper to the B?chner funnel, then turn on the vacuum.Slowly decant the organic phase into the B?chner funnel. Avoid transferring the drying agent, as the filter may clog. When most of the liquid has been transferred onto the funnel and drained into the flask below, add the remainder with the drying agent and allow it to sit for a few minutes.Turn off the vacuum and transfer the filtered solution into a dry round bottom flask. Connect the round-bottom flask to a rotary evaporator and remove all solvent under reduced pressure. The solid or liquid that remains should now be dry.To dry an already solid reagent?place the compound in an open container and determine its weight. Then place it into a drying oven set to a temperature below the melting point of the solid. Allow the reagent to dry for several hours inside the oven.Remove the container from the oven and place it into a desiccator. Then, allow the sample to cool to room temperature. Reweigh and ensure that the mass is less than before oven drying. Repeat the drying steps until the weight no longer changes. When this happens the reagent is sufficiently dry.If the reagent does not need to be used immediately, flush the container with an inert gas such as nitrogen and wrap Parafilm around the lid. Place the container inside a desiccator and store until the reagent is needed.Anhydrous reactions are used in a variety of important organic chemistry syntheses.A classic example for a reaction that must be done under anhydrous conditions is the Grignard reaction. In the first step of the reaction?it is imperative that not even the smallest traces of water be present. In the presence of water?the Grignard reagent will preferentially act as a base, resulting in the loss of the nucleophilic activity and form undesirable byproducts.Many organic syntheses must be performed in extremely dry conditions, like with this example of organic magnet synthesis. The precursor material in this case, sodium metal, is pyrophoric, meaning that it is extremely moisture sensitive and can be flammable or even explosive when in contact with moisture in the air.Lithium ion batteries are also extremely moisture sensitive?and must be assembled in a glove-box or dry room. The negative electrode consists of a lithium compound, while the electrolyte contains a halogenated lithium salt. Since lithium is moisture sensitive?any trace water introduced into the battery cell itself would diminish capacity.You've just watched JoVE's introduction to Preparing Anhydrous Reagents and Equipment. You should now understand how to prepare glassware, solvents, and reagents that are all anhydrous for use in chemical reactions.Thanks for watching!

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Chemistry

Organic Chemistry

moisture-free setup for organic reactions

Many organic reactions must be set up without water. Moisture in the air can react with sensitive reagents before the reaction even starts. When that happens, the desired reaction may fail or give poor yields because the reactants have changed chemically.

To prevent this, the reaction is run under an inert atmosphere. An inert atmosphere is a gas environment that does not react easily with the chemicals in the flask. Nitrogen gas is often used, and argon may be used for reactions that are even more sensitive.

Every part of the setup must be anhydrous, meaning free of water. That includes the reagents, the solvents, the glassware, and any equipment that will touch the chemicals. For extremely water-sensitive work, the reaction is done inside a glovebox. A glovebox is a sealed chamber that keeps out moisture and lets the chemist work through built-in gloves.

Moisture-Free Setup for Organic Reactions

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assembly of a reflux system for heated chemical reactions

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organic chemistry

This collection features techniques routinely used in the organic chemistry lab, focusing on regulating temperature and atmosphere during chemical reactions and post-reaction refinement.

Learn how moisture-sensitive organic reactions use inert gas, dry reagents, anhydrous glassware, and gloveboxes to keep water out of the setup.

Moisture-Free Setup for Organic Reactions | JoVE K12

HS. Chemical Reactions

HS-PS1-2.

HS-PS1-5.

HS-PS1-7.

Dana Lashley

Overview

Principles of Preparing Anhydrous Reagents and Equipment

Drying Glassware

Drying Solvents

Drying Reagents

Applications

Summary

Periodic Classification of the Elements

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The Aufbau Principle and Hund's Rule

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Source: Laboratory of Dr. Neal Abrams &#8212; SUNY College of Environmental Science and Forestry
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HS-PS1-1.

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VSEPR Theory and the Basic Shapes

Overview of VSEPR Theory

Valence shell electron-pair repulsion theory (VSEPR theory) enables us to predict the molecular structure, including approximate ...

vsepr-theory-and-the-effect-of-lone-pairs

VSEPR Theory and the Effect of Lone Pairs

Effect of Lone Pairs of Electrons&nbsp;on Molecule Geometry

It is important to note that electron-pair geometry around a central atom is not the same ...

Predicting Molecular Geometry

VSEPR Theory for Determination of Electron Pair Geometries

The following procedure uses VSEPR theory to determine the electron pair geometries and the ...

Molecular Shape and Polarity

Dipole Moment of a Molecule

Polar covalent bonds connect two atoms with differing electronegativities, leaving one atom with a partial positive charge ...

Valence Bond Theory

Overview of Valence Bond Theory

Valence bond theory describes a covalent bond as the overlap of half-filled atomic orbitals (each containing a single ...

Hybridization of Atomic Orbitals I

The mathematical expression known as the wave function, &#x3C8;, contains information about each orbital and the wavelike properties of electrons in an ...

Hybridization of Atomic Orbitals II

sp3d and sp3d&nbsp;2 Hybridization

To describe the five bonding orbitals in a trigonal bipyramidal arrangement, we must use five of the valence shell ...

Molecular Orbital Theory I

Overview of Molecular Orbital Theory

Molecular orbital theory describes the distribution of electrons in molecules in the same way as the distribution of ...

Molecular Orbital Theory II

Molecular Orbital Energy Diagrams

The relative energy levels of atomic and molecular orbitals are typically shown in a molecular orbital diagram. For a ...

Molecular Orbital (MO) Theory

Source: Tamara M. Powers, Department of Chemistry, Texas A&#38;M University
This protocol serves as a guide in the synthesis of two metal complexes ...

Intermolecular vs Intramolecular Forces

Intermolecular forces (IMF) are electrostatic attractions arising from charge-charge interactions between molecules. The strength of the intermolecular ...

Intermolecular Forces

Atoms and molecules interact through bonds (or forces): intramolecular and intermolecular. The forces are electrostatic as they arise from interactions ...

Molecular and Ionic 
Solids

Crystalline solids are divided into four types: molecular, ionic, metallic, and covalent network based on the type of constituent units and their ...

comparing-intermolecular-forces-melting-point-boiling-point

Comparing Intermolecular Forces: Melting Point, Boiling Point, and Miscibility

Intermolecular forces are attractive forces that exist between molecules. They dictate several bulk properties, such as melting points, boiling points, ...

Plan and conduct an investigation to gather evidence to compare the structure of substances at the bulk scale to infer the strength of electrical forces between particles.

HS-PS1-3.

Radioactivity and Nuclear Equations

Nuclear chemistry is the study of reactions that involve changes in nuclear structure. The nucleus of an atom is composed of protons and, except for ...

Types of Radioactivity

The most common types of radioactivity are &#945; decay, &#946; decay, &#947; decay, neutron emission, and electron capture.
Alpha (&#945;) decay is the ...

Nuclear Stability

Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10&#8722;15 meters, a nucleus is ...

Nuclear Binding Energy

The difference between the calculated and experimentally measured masses is known as the mass defect of the atom. In the case of helium-4, the mass defect ...

Radioactive Decay and Radiometric Dating

Radioactivity is a spontaneous disintegration of an unstable nuclide and is a random process, as all the nuclei in the sample do not decay simultaneously. ...

Nuclear Fission

Many heavier elements with smaller binding energies per nucleon can decompose into more stable elements that have intermediate mass numbers and larger ...

Nuclear Power

Controlled nuclear fission reactions are used to generate electricity. Any nuclear reactor that produces power via the fission of uranium or plutonium by ...

Nuclear Fusion

The process of converting very light nuclei into heavier nuclei is also accompanied by the conversion of mass into large amounts of energy, a process ...

Nuclear Transmutation

Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with ...

Biological Effects of Radiation

All radioactive nuclides emit high-energy particles or electromagnetic waves. When this radiation encounters living cells, it can cause heating, break ...

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Determining Rate Laws and the Order of Reaction

Source: Laboratory of Dr. Neal Abrams &#8212; SUNY College of Environmental Science and Forestry
All chemical reactions have a specific rate defining the ...

Develop models to illustrate the changes in the composition of the nucleus of the atom and the energy released during the processes of fission, fusion, and radioactive decay.

HS-PS1-8.

Properties of Transition Metals

Transition metals are defined as those elements that have partially filled d orbitals. As shown in Figure 1, the d-block elements in groups 3&#8211;12 are ...

Coordination Compounds and Nomenclature

In most main group element compounds, the valence electrons of the isolated atoms combine to form chemical bonds that satisfy the octet rule. For ...

Metal-Ligand Bonds

The hemoglobin in the blood, the chlorophyll in green plants, vitamin B-12, and the catalyst used in the manufacture of polyethylene all contain ...

Coordination Number and Geometry

For transition metal complexes, the coordination number determines the geometry around the central metal ion. Table 1 compares coordination numbers to ...

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Physical Properties Of Minerals I: Crystals and Cleavage

Source: Laboratory of Alan Lester - University of Colorado Boulder
The physical properties of minerals comprise various measurable and discernible ...

Communicate scientific and technical information about why the particulate-level structure is important in the functioning of designed materials.

HS-PS2-6.

Moisture-Free Setup for Organic Reactions

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