Source : Vy M. Dong et Daniel Kim, Department of Chemistry, University of California, Irvine, CA
Synthèse organique est un réactif facilement disponible ou comment transformer un produit plus de valeur. Avoir propre verrerie est cruciale pour l’efficacité de ce processus. Verrerie sale peut potentiellement affecter la réaction et faire isolement du produit final plus difficile. Ainsi, un chimiste synthétique doit garder la verrerie impeccable. Les méthodes décrites ici détaillera les différentes techniques utilisées régulièrement pour enlever les matières organiques, des métaux, graisse et sels de nettoyage pour vitres.
Clean glassware is simple and fundamental in organic chemistry practice. The knowledge of how to remove tough stains, residues, and contaminates provides the confidence to use glassware without worry of contamination.
By following the guidelines to cleaning glassware, the chemist can focus on the chemistry and worry less about contamination from glassware. The above protocol demonstrated how to clean glassware using warm, soapy water, acid wash, base bath, and aqua regia, and how to dry glassware, as well as advice for cleaning glass ground joints. Disposal of cleaning solutions were also discussed briefly. These glass cleaning procedures work for all kinds of glassware including, but not limited to: round-bottom flasks, Erlenmeyer flasks, separatory funnels, chromatography columns, stir bars, spatulas, funnels, filters, graduated cylinders, beakers, Schlenk flasks, and test tubes.
Ensuring clean glassware can enforce good practices beyond the organic chemist's bench. Having clean equipment in general is important for all types of applications within and outside of chemistry and science. In each case, it is important to consider the material of the item being cleaned and the tools required for cleaning.
We use simple acid and base solutions to clean materials in everyday life. For example, chefs need clean pots and pans, and while these pots and pans do not need acetone for finishing, usually warm, soapy water can remove sticky grease. Interestingly, some people suggest boiling a dirty pot with vinegar to achieve a strong clean, and it is not too surprising that acetic acid is the major ingredient in vinegar. Additionally, baking soda is sodium carbonate and a common house-hold cleaning tool.
Another example of an application where having clean equipment and glassware is essential is quantification analysis for those in an analytical field. Cross-contamination or dirty instrumentation can give rise to unreliable data, affecting many different areas of work; this could be in hospitals, clinics, a crime scene, or on a manufacturing line.
Finally, cleaning products are sold on the market for everyday use for glassware, with the added purpose of cleaning bathroom tiles, windows, and mirrors. These are sometimes filled with organics and may be mildly acidic or basic. This combination can remove grease and water stains.
Clean glassware is crucial for the efficacy and efficiency of chemical synthesis.
Organic synthesis is about transforming a readily available reagent into a more valuable product. Any source of contamination, such as dirty glassware, can potentially affect the reaction and make isolating the final product more challenging.
Just because a piece of glassware looks clean, does not mean that it is. When in doubt, clean it.
This video will illustrate many of the basic cleaning methods for glassware used in organic chemistry reactions.
We will begin our survey with a general method used for cleaning all glassware.
First, rinse the glassware with an organic solvent-such as acetone-to remove any excess organic oils. Deposit this rinsing into the appropriate safety container.
Next, mix warm tap water and soap. Using this and an appropriate brush, scrub the inside of the glassware. Then, rinse with warm tap water to remove the soapsuds.
Wash away the tap water with deionized water to avoid hard water stains. Lastly, rinse the glassware with acetone to remove the deionized water and expedite the drying process. This method on its own is sufficient when a specific residue removing technique is not required. When such a technique is called for this general method will still be used after the residue has been removed.
Some organic residues, metal salts, and stuck-on bases require a mild acid wash. Non-oxidizing acids can be poured down the drain when finished. Organic acids, on the other hand, must be neutralized and deposited in a water-based liquid waste container.
To begin, prepare a 1 M hydrochloric acid solution in deionized water. Then, inside a fume hood, add some of this acid solution to the glassware being cleaned. Make sure to swirl the solution to the dirty areas. When finished, depose of the acid solution appropriately. Finally, wash the glassware with soapy water, as outlined in the general procedure for all glassware.
Soaking glassware in a base bath may help when mild acid washes and soapy water are not enough. Care should be taken, as this bath is strongly basic and caustic, and can affect finely-calibrated glassware.
To begin, add a 2 M solution of potassium hydroxide in isopropyl alcohol to a designated cleaning bucket. Next, to prolong the life time of the base bath, clean the glassware using the general “soapy water” method. Then, carefully place the glassware in the base bath, making sure to remove as much air as possible.
Let the glassware soak overnight. After this, carefully remove the glassware from the bucket, pouring the base solution back into the bucket. Rinse with deionized water. The base bath can be used multiple times before replacing.
Finally, dry the glassware with acetone.
In situations with residual metals, aqua regia may be required. Care should be taken, as this acid wash is strongly acidic, oxidizing, and caustic-and can corrode stainless steel.
To begin, create a small batch of aqua regia by mixing nitric acid and hydrochloric acid in a 3 to 1 ratio. These acids are colorless, but when mixed will fume and turn dark orange.
Next, pipette the mixture into the dirty glassware. Swirl to dissolve residual metals. After this, pour the aqua regia into a separate container for treatment.
Neutralize the used aqua regia with sodium bicarbonate. Then, deposit the neutralized solution in an aqueous waste container. Using the general method, wash the glassware with soapy water.
Glass ground joints can easily become stuck if not cleaned properly. Clean glass joints are frosted in appearance. Dirty joints, on the other hand, are usually clear – indicating contamination with oil or grease.
First, clean the glassware using an appropriate method. Then, use a paper towel soaked in ethyl acetate and a small spatula to clean the inside, outside, and the edges of the joint.
After this, let the glassware dry.
In reactions that are water sensitive, it is important to drive off water and limit exposure to outside air. While there are several methods to remove water, using an oven is the safest, and preferred.
To begin, place the glassware into the oven. Turn the oven on, and leave the glassware inside for 30 to 60 min. After this, use oven gloves to remove the glassware.
Quickly cap with a septum. Flow nitrogen through the glassware while it is still hot. Once the glassware cools, it will be enriched with an inert atmosphere containing no water vapor. The glassware is now ready for use.
Now that we’ve surveyed the most common techniques used to clean laboratory glassware, we’ll discuss some examples.
The successful synthesis of high purity product is reliant on properly cleaned glassware. In this example, metal nanoparticles are synthesized, and then encapsulated in various types of polymer.
First, gold nanoparticles are synthesized in glassware cleaned using the aqua regia process. After this, the nanoparticles are isolated by centrifugation.
The isolated nanoparticles are then transferred to a glass vial containing a solution of PSPAA for encapsulation.
Clean glassware is also important in many fields when attempting to quantify a compound of interest. For example, having clean instrumentation is important when investigating a crime scene. If not cleaned properly, contaminations could give rise to unreliable data.
You’ve just watched JoVE’s introduction to cleaning glassware. You should now understand acid washes, base baths, and the general cleaning procedure for all glassware. Thanks for watching!
