Thin-Layer Chromatography Lab

The unknown sample was identified to contain Acetaminophen, Aspirin, and caffeine based on comparison of known Rf values (Table 1). When comparing the traveled UV lit spots (figure 1), Aspirin and Ibuprofen traveled the same distance from the start line. Unknown sample 16 contains Aspirin not Ibuprofen, due to the intensity of the spot under UV light. Aspirin and the unknown shared that same intensity, whereas Ibuprofen did not share that same strength of brightness. The distance traveled by the samples was dependent upon their affinity for the mobile phase 200:1 ethyl acetate – acetic acid. The samples that traveled the furthest like the Aspirin and Ibuprofen were the most soluble in the mobile phase. The samples that traveled the shortest

The purpose of experiment three was to identify the unknown component in the drug Panacetin. The use of physical properties can help identify unknown compounds and estimate the degree of their purities. In this experiment, solubility in boiling water and melting point were used to determine if the unknown was acetanilide or phenacetin. Since both compounds are soluble in boiling water and insoluble in cold water, recrystallization was used to remove any impurities from the solid.

Perform the following with three 0.05g samples of unknown and the following solvents: methanol, water and toluene

Adsorption chromatography occurs when “one substance form[s] some sort of bonds to the surface of another one”, creating intermolecular forces between the two substances (Chemguide). For thin layer chromatography, the components of the mixture are adsorbed onto the stationary phase that covers the plate (Chemguide). The more polar a substance is, the more strongly adsorbed it is (Chemguide) and the strong intermolecular forces then result in a slower rate of migration with respect to the moving phase. As the solvent touches the TLC plate, the solute (mixture) is allowed to move up the TLC plate

Other information that can be obtained from a TLC analysis is the progress of a chemical reaction, which can be done by taking samples from the reaction mixture at various intervals and spotting them on TLC plates and taking down the Rf factor. Also TLC analysis can be used to determine the optimum conditions required to obtain a high yield of the desired product with little to no side products. Yield can be ascertained via TLC analysis in that the reactant and product intensity on the TLC plate will have varying degrees of intensity. At the end of the reaction, the product should have the most intensity, while the reactant has the least intensity. At the beginning of the reaction, it would be the other way around. With this, you can determine the percent yield of the

Both Aspirin and the Unknown are soluble in dichloromethane, due to their non-polar characteristics. To separate the two components, sodium bicarbonate was added (see figure 3). Sodium bicarbonate reacted with aspirin and converted it to a salt, also forming water and carbon dioxide. It was observed that the solution "fizzed" when this reaction took place, showing the release of carbon dioxide. The newly formed salt then traveled to an aqueous layer where it was soluble, while the unknown remained in the dichloromethane layer. The two layers were then separated. To collect an aspirin solid, the combination of the addition of HCl and the process of vacuum filtration helped to break down the salt and form a solid. Then the solid was placed in the Fisher Scientific Biotemp Oven to dry it to a constant mass of 0.091 g, 32.97% of the total composition. The

I measured out 3grams of Panacetin and then mixed it with CH2Cl2. Then after the filtration I was left with sucrose isolated, and then a substance containing aspirin and

There might have been some mistakes made while transferring the ingredients from the beaker and the funnel to the flask and the burret.

6. Purpose: to clarify the mechanism for the cycloaddition reaction between benzonitrile oxide and an alkene, and to test the regiochemistry of the reaction between benzonitrile oxide and styrene; to purify the crude product of either trans-stilbene, cis-stilbene, or styrene reaction.

In the first part, there may have been cross contamination of materials, especially since periods before us had already performed the experiment. During chromatography, our spot sizes were initially very varied, as we didn’t know exactly how much of each substance to place when we began. Thus, the substances in more abundance would have greater opportunity to travel up with the eluent, skewing the results. In the beginning, we even put 6-7 drops, causing some of the substances to mix together. Touching the TLC plate may also have disrupted some of the substances traveling up.

There were two layers inside of the funnel. An aqueous (top) layer and an organic(bottom) layer. Dichloromethane was an organic layer it was denser. A TLC of biphenyl/ p-toluidine was conducted and determined to be impure because there were two spots. The bottom spot was p-toluidine and higher spot was biphenyl. After preforming extraction, a TLC was conducted on the isolated biphenyl. The isolated biphenyl was determined to be pure because there was one spot and 48.8 % recovery. Also, a TLC was conducted for the isolated p-toluidine and it was determined to be pure because of only one spot with 36%

In Table 1, fluorene travels further up the TLC plate versus fluorenone since a more nonpolar 80:20 pentane-ether developing solvent is used. Since fluorine is more nonpolar than 9-fluorenone, it will be more soluble in the highly nonpolar solvent and enter the mobile phase easier than the polar 9-fluorenone. Fraction 2 is expected to have two different spots because this is the collection of the eluted solution between Fraction 1 and Fraction 3, where the fraction contains both the remaining fluorene and 9-fluorenone. Fraction 1, however, should not contain any 9-fluorenone since if correctly performed only fluorene and pentane should have eluted out in the mobile phase. A crack in the column during the elution of Fraction caused one section

Once the dichloromethane/caffeine solution was dry, the solution was placed in a clean test tube and saved to perform TLC

     Liquid chromatography is an analytical technique that is useful for separating ions or molecules that are dissolved in a liquid phase. If the sample solution is in contact

AIM : Thin-Layer Chromatography can show many different characteristics of a mixture. It is recognized for isolation , separation ,identification, and anaylsis of the mixture’s components. The purpose of this experiment is to separate carbohydrates into its pure components such as mixtures of monosacrides by TLC. TLC is used to identify sugars in normal and pancreatic disease urine, the procedure is easy and reproducible .