Thin Layer Chromatography Lab Report

TLC Analysis Data Table Compound Std. Aspirin Std. Caffeine Rf values 0.38 0.65 Error ---~ 0% 29% 5%

2. The TLC results showed two different spots that traveled different distances on the TLC plate, one for ethyl vanillin and one for ethyl vanillin alcohol which proves there is no evidence of the starting material in our final product. The product (ethyl vanillin alcohol) was more polar and interacted more with the solvent than our starting material (ethyl vanillin). This increase in polarity is due to the extra alcohol group in the ethyl vanillin alcohol and the smaller Rf value also indicates it is more polar and pure than the ethyl vanillin.

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

The makeup of a compound drastically changes its intermolecular forces (IMFs) with the polar silica gel of a TLC plate; this concept is responsible for the variability of Rf values observed throughout the course of lab. The weaker the IMFs, the further a compound will travel through the silica. For instance, ionic interactions are the strongest IMF, but were not present during this experiment. H-bonding IMFs had the greatest impact for our specific compounds. Resorcinol and 3-chlorobenzoic acid exhibited low Rf values, due to its ability to H-Bond to silica’s hydrogen donors and oxygens acceptors (See graph 1). Both were adept to strongly H-bonded to silica because the compounds contained at least 1 H-donor and 2 H-acceptors. Thus, stronger/more

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

Which one of the statements concerning valence bond (VB) and molecular orbital (MO) bond theories is correct?

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 thin layer chromatography a stationary phase, silica gel with a glass backing, is dotted on a pencil drawn

First, dichloromethane was the least polar solvent, so it barely moved up the plate. Hence, the spots on the TLC plate stayed at almost the same place they were spotted on, and separation did not occur. As a result, the retention factor (Rf) values for these components were too small. In addition, the second solvent, methanol, was the most polar solvent out of the three, and the solvent moved up the plate too quickly. This resulted in the components moving up the plate based on the solvent's polarity instead of their own, and a smear of all components at the solvent front was observed. Hence, the Rf values could not be determined. Lastly, ethyl acetate, a moderately polar solvent, moved up the plate with moderate speed. This gave the components time to move up the plate according to their polarity, and the Rf values could be used to identify the unknown compound. According to the TLC method with ethyl acetate solvent, the unknown compound had the same Rf value with acetanilide (Rf = 0.40). As a result, the unknown compound was identified as

• Molecules with small differences in absorption wavelengths can be detected well due to their differences in separation time. i.e one which travels faster is measured prior to the other which is measured later. This is the prime advantages if HPLC which makes it

The Thin Layer Chromatography of Drugs lab taught me how chromatography could be used to identify the compounds of an unknown drug. This procedure relied on using compounds that had a known travel distance, which served as the control, and examining how far the compounds in the unknown drug traveled. The results of this experiment indicated that drugs are chemical molecules with a diverse amount of compounds i.e.: caffeine, acetaminophen, asprin, etc. The essentials of this lab relied on two factors that allow for the separation of different compounds from the drug.

     In liquid chromatography, the separator is called the column and consists in most cases of a tube filled with porous material called the stationary phase. A liquid, called the mobile phase, flows through the tube between the particles of stationary phase material. A liquid sample is taken from a mixture to be analyzed and introduced to a part of the system that is at elevated pressure. The sample is then transported to a separator by the flow in the system.

The type of solvent used will determine the extent of separation of each component. The concept that like constituents are attracted to each other and are miscible plays an essential role in determining the migration distances of various components of the mixture. Each component has the option of entering either the mobile or stationary phase and the polarity of the solvent will influence its pathway. For example, a more polar solvent will compete with the polar components for positions on the polar adsorbent and also transport its counterpart along the plate until it finally becomes adsorbed. As a result, the polar components of the mixture will remain in the mobile phase for a longer period

Gel-Filtration Chromatography is a commonly used method used in order purify a protein from a mixture, by means of separations. Different biomolecules differ in size, or their molecular weight. In the gel matrix inside the chromatography column, there are gel beads which are porous to allow certain sized molecules to enter. The molecules that are able to enter the pores of the gel, are held in stationary phase and will elute from the column later on, these are usually smaller, to medium sized molecules. Larger molecules that are not able to fit in the pores will elute out of the column first, they are involved in mobile phase where they just go straight through the column without interacting with the gel beads. Smaller molecules will have a higher elution volume, while the larger molecules will have a lower elution volume. The volume to elute the protein is inversely proportional to the molecules size.

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 .