Principles Of Column Chromatography

The current experiment sought to prepare 1,6-hexanedioic acid (adipic acid) by catalytic oxidation of cyclohexene in the presence of a phase-transfer catalyst (Aliquat 336), using sodium tungstate as a catalyst and hydrogen peroxide as an oxidant.

If a sample’s Rf is lower, that means that it remained closer to the stationary phase. In both variations of the experiment, red dye #40 remained the closest to the stationary phase (on average). Therefore, the red dye #40 had the lowest rate of flow value. The intermolecular forces of the red dye are responsible for its low distance traveled. The molecules of the chromatography paper have strong intermolecular bonds that are highly polar. The red dye is attracted to the paper because of their similar characteristics. The negative and positive ends of both the paper molecules and the red dye #40 molecules attract to each other. It is extremely difficult for the isopropyl alcohol and the sodium chloride solutions to interfere with the bonds of paper and ready dye #40, as a result, both solutions are unable to fully dissolve red dye #40. . NaCl and isopropyl alcohol have very strong intermolecular forces, but the forces of the paper’s molecule were able to attract red dye #40 because they were even

The purpose of this experiment is to convert carbonyl compounds to alkenes using Wittig reaction. In this case we will be synthesizing Trans-9-(2-phenylethenyl) anthracene from benzyltriphenylphosphonium chloride and 9-anthraldehyde. We will also aim to obtaining a high percent yield and purity for the synthesis of Trans-9-(2-phenylethenyl) anthracene. The mechanism for this reaction goes thus:

The eluting solvent passed down the column by the gravity and an equilibrium was established between the solute absorbed by the absorbent (silica gel in this experiment) and the eluting solving flowing down. Since the components in the sample had different polarity and they interacted with the stationary phase and the mobile phase differently, the components would be carried by the solvent to a different extent and a separation of the components could be achieved.

As a result, polar compounds have long retention times on polar stationary phases and shorter retention times on non-polar columns using the same temperature. Chiral stationary phases that are based on amino acid derivatives, cyclodextrins and chiral silanes are capable of separating enantiomers because one enantiomer interacts slightly stronger than the other one with the stationary phase, often due to steric effects or other very specific interactions. For instance, a modified -cyclodextrin column is used in the determination of the enantiomeric excess in the chiral epoxidation experiment (Chem

In chromatography, the retardation factor, is the fraction of a chemical constituent that undergoes analysis in the mobile phase of the chromatographic system.1 The Rf is defined as the ratio of the

The method used in this experiment is called an oxidation reaction. An oxidizing agent takes away electrons from other reactants during a redox reaction. The oxidizing agent typically takes these electrons for itself, thus gaining electrons and being reduced (Helmstein, Ph. D 2017). The organic oxidant used in this experiment is sodium hypochlorite, which is also known as “household bleach’. Sodium hypochlorite in acetic acid is an alternate oxidizing agent used for the development of ketones that was developed by Stevens, Chapman and Weller due to the many advantages it displays (J. Org. Chem, 1980, 45, 2030). This particular oxidation of sodium hypochlorite is an exothermic reaction meaning that it releases heat as an energy form. Due to the exothermic nature of this experiment, temperature ranges should be monitored throughout the experiment. The overall objective in this experiment is to yield a

The main type of chromatography process is paper chromatography. Paper chromatography process was what we used for/during this lab. Paper chromatography is used to separate the components of ink, dyes, plant compounds (chlorophyll), make-up, and other substances. The other chromatography processes include: Liquid, Thin-Layer, and Gas. Liquid chromatography is used for identifying unknown plant pigments and other compounds.

The Rf value is the distance that a certain compound traveled divided by the distance traveled by the solvent front unique to paper and thin layer chromatography. Both distances are measured from a common origin point. For this measurement to be as close to accurate as

Leaf litter was collected on a hike through the Christopher Creek area in Payson, Arizona. Small amounts of this biomass will be burned at a time. The resulting aerosols will be collected through a drier vent attached to a high volume air sampler. Burn aerosols will be collected on hydrochloric acid-cleaned cellulose filters. Acid-cleaned cellulose filters are commonly used when performing trace metal analysis on aerosols because they dissolve easily in concentrated acid and are cost effective. Filter cleaning and sample preparation will follow the procedure outlined in Mead, et al. (2013). [1]

O and C-O bonds are polar and the bond dipole moments don't cancel each other out. Due to this eluent being polar most of the molecules remained with the compound as it travelled up the thin layer chromatography paper. We did not choose Ethyl acetate as the best eluent because most of the Rf , except for caffeine, were very close together in value. This would make it harder to distinguish which active ingredient each compound

Methods used to separate miscible solvents include thin layer chromatography (TLC) as well as column chromatography. A method used to separate a mixture of miscible solvents is column chromatography, which is used to purify and separate compounds. The particular speed of the solvents used in the experiment depended upon the properties, being polar or nonpolar, as well as the properties of the prepared column (INSERT SOURCE HERE). With column chromatography, there are two phases that include mobile and stationary phases. In the experiment performed, the glass column used was first packed with a piece of cotton followed by a layer of sand in order to keep the silica gel in place and also to prevent the gel from flowing out of the tube when the particular solvent was added. Based upon whether the

Some materials that appear homogenous are actually a mixture of different substances, one example being ink. To see what colors make up black ink, one can allow the substance to move across a fixed, absorbent material such as paper. This technique, called chromatography, is a forensic method of separating a mixture of chemicals into their individual components. Although the separation of colors is the most elementary application of chromatography, the process of a liquid or gas mixture moving over a stationary state of matter (liquid or solid) is a tool used by local and federal law enforcement to analyze and solve crimes.

In this experiment the objective was to analyze different compounds that moved through the Vernier Mini GC. With the assistance of a Vernier Mini GC, retention time at various temperatures could be observed. When a compound is put through the Vernier Mini GC, compounds that were more complex (non-polar, high boiling point, and molecular weight) had an extended retention time compared to simple compounds. Retention time is the time it takes for a compound to exit the column after being injected. This experiment, the retention time of different compounds were observed. Prior to completing the experiment, a hypothesis was constructed as regards to how structure affects retention time. The first part of experiment hypothesis is if the molecular

The data that was collected throughout the experiment shows the distance the amino acid traveled from the origin. This data was used to calculate the retardation factor also known as the Rf value; the distance that the spot traveled divided by the distance the solvent traveled. Based off of our data, the non-polar amino acids show an upward linear trend in Rf as molecular weight increases. Conversely, the more polar the amino acids are the greater the downward linear trend is seen, as shown in figure 1.3. Based off of the direction that the amino acids moved on the thin layer chromatography sheet we can deduce that the hydrophobic molecules moved away from the solvent while the hydrophilic molecules still moved but remained closer to the origin of the sheet. The Rf value can provide evidence as to what the compound was. One way to fully authenticate the identity of a compound is to run a TLC sheet side by side with the compound that you are trying to identify. You can identify a substance if both compounds have the same Rf; they are likely identical substances. However, if their Rf values differ they are not the same compounds. We were able to see this take place in our experiment. As one can see from figure 1.3 D-alanine and L-alanine that have the same molecular structure, but are just mirror images on of one another, both have the same Rf value.