What is the impurity that must be removed from the benzaldehyde reagent before it can be used in this experiment?
this is from are Benzil lab
in this lab, benzoin condensation of benzaldehyde will be carried out with a biological coenzyme, thiamine hydrochloride, as the catalyst:
Procdure.
Reaction Mixture-Add 0.3 g of thiamine hydrochloride to a erlenmeyer flask. Dissolve the solid in 0.45 mL of water by swirling the flask. Add 3.0 mL of 95% ethanol, and swirl the solution until it is homogeneous. To this solution add 0.9 mL of an aqueous sodium hydoxide solution and swirl the flask until the bright yellow color fades to a pale yellow color. Weigh the flask and solution, add 0.9 mL of benzaldehyde, and reweigh the flask to dtermine an accurate weight of benzaldehyde introduced to the flask. swirl the contents of the flask until it is homogeneous. Stopper the flask, and let it stand in a dark place for at least 2 days.
Isolation of crude Benzoind-allow about 5 minutes for the crystals of benzoin to form fully. place the flask, with crystals, into an ice bath for 5-10 minutes.
Break up the crystalline mass with a spatula, swirl the flask rapidly and quickly transfer the benzoin to a hirsch funnel under vacuum. Was the crystals with three 1.0 mL portions of ice cold wateer. allow the benzoin to dry in the hirsch funnel by drawing air through the crystals for about 5 mins. Transfer the benzoin to a watch glass and allow it to dry in air for one day. The product may be dried in a few minutes in an oven set at about 100 C
In the given experiment, the impurity that needs to be removed from the benzaldehyde reagent before using it is water.
To remove water as an impurity, the following steps can be taken:
1. Begin by obtaining the benzaldehyde reagent.
2. To remove water, you can use a technique called drying or dehydration.
3. One common method to remove water is by using a drying agent such as molecular sieves, anhydrous calcium chloride, or anhydrous sodium sulfate.
4. Take an appropriate amount of drying agent (usually a small amount) and add it to the benzaldehyde reagent in a separate clean and dry container.
5. Mix the drying agent and benzaldehyde reagent thoroughly by gently swirling or shaking the container.
6. Allow the mixture to sit for a period of time, usually around 10-15 minutes, to allow the drying agent to absorb the water.
7. After the designated time, separate the drying agent from the benzaldehyde reagent. This can be done by filtering or decanting the mixture to leave behind the drying agent and obtain the purified benzaldehyde reagent.
8. The purified benzaldehyde reagent can now be used in the experiment without the impurity of water affecting the results.
It is important to ensure that the drying agent used to remove water is of high quality and completely free from any other impurities.
Note: The specific drying agent and procedure used may vary depending on the experiment and the available resources. Always refer to the experiment protocol or consult with your instructor for the appropriate drying technique in your specific case.