The purpose of this lab was to better understand how the vibrational frequencies of five different compounds were affected by the molecular shape as well as substitution. We were able to determine this using an IR spectrum of each compound as well as by predicting the vibration frequencies by using Gauss View. Furthermore, students were also able to demonstrate their skills in reading IR spectrums. For the first part of the lab, Michelle and I created the molecule benzophenone and determined the carbonyl stretch, which was 1770.10cm-1, and the C-H stretch which was at 3174.41cm-1. After predicting the stretches, we obtained the actual compound and ran an IR spectrum in order to observe the frequencies. However, the compound had to be placed in a bolt and tightened before the IR spectrum could be run. An infrared spectroscopy (IR spectroscopy) is based on …show more content…
Once our molecule was completed, we were able to begin the calculations portion. Once the calculations were completed, we were able to see how benzophenone was affected by the different vibrations that we had selected. After, observing benzophenone, we were able to determine the carbonyl stretch (which was at 1770.10cm-1) and the asymmetric C-H stretches at the carbon atoms nearest to the carbonyl (which was at 3174.41). Once this was completed, we moved on to the IR spectra portion of the lab. We first obtained potassium bromide and benzophenone. The benzophenone was grinded into powder and then added to the potassium bromide—and mixed. This mixture was then placed into a pellet press barrel with one of the bolts halfway up the chamber. The other bolt was then inserted and tightened by hand, later using wrenches to further tighten the bolt. Once the pellet was transparent, we were able to run it under the IR spectrum. The data was then shared with our
The analyzed yellow#5 wavelength was determined to 395nm because the actual wavelength 427nm was restricted in the Micro lab. The R2 value of the graph is 0.9827, and the level of data accuracy it indicated extremely weak data correlation. The first one dilution data points excluded from the standard curve because the point is not in the linear curve. The first concentration and absorbance value are the highest point in the graph that cannot connect as linear with another data point. After removing the first data point, the standard curve is clear and make
yield of the pure product was determined to be 95.42%. PURPOSE The purpose of this lab was to perform an electro-philic aromatic substitution and determine the identity of the major product. TLC was used to detect unreacted starting material or isomeric products present in the reaction mixture. RESULTS The theoretical yield of the m-nitrobenzoate was determined to be 4.59 grams.
Triphenylmethyl Bromide. A 400 mL beaker was filled with hot water from the tap. Acetic acid (4 mL) and solid triphenylmethanol (0.199 g, 0.764 mmol) were added to a reaction tube, with 33% hydrobromic acid solution (0.6 mL) being added dropwise via syringe. The compound in the tube then took on a light yellow color. The tube was then placed in the beaker and heated for 5 minutes. After the allotted time, the tube was removed from the hot water bath and allowed to cool to room temperature. In the meantime, an ice bath was made utilizing the 600 mL plastic beaker, which the tube was then placed in for 10 minutes. The compound was then vacuum filtered with the crystals rinsed with water and a small amount of hexane. The crude product was then weighed and recrystallized with hexane to form fine white crystals, which was triphenylmethyl bromide (0.105 g, 0.325 mmol, 42.5%). A Beilstein test was conducted, and the crystals produced a green to greenish-blue flame.
The IR spectrum that was obtained of the white crystals showed several functional groups present in the molecule. The spectrum shows weak sharp peak at 2865 to 2964 cm-1, which is often associated with C-H, sp3 hybridised, stretching in the molecule, peaks in this region often represent a methyl group or CH2 groups. There are also peaks at 1369 cm-1, which is associated with CH3 stretching. There is also C=O stretching at 1767 cm-1, which is a strong peak due to the large dipole created via the large difference in electronegativity of the carbon and the oxygen atom. An anhydride C-O resonates between 1000 and 1300 cm-1 it is a at least two bands. The peak is present in the 13C NMR at 1269 and 1299 cm-1 it is of medium intensity.
Benzyl bromide, an unknown nucleophile and sodium hydroxide was synthesized to form a benzyl ether product. This product was purified and analyzed to find the unknown in the compound.
After performing the second TLC analysis (Figure 4), it was apparent that the product had purified because of the separation from the starting spot, unlike Figure 3. In addition, there was only spot that could be seen on the final TLC, indicating that only one isomer formed. Since (E,E) is the more stable isomer due to a less steric hindrance relative to the (E,Z) isomer, it can be inferred that (E,E) 1,4-Diphenyl-1,3-butadiene was the sole product. The proton NMR also confirmed that only (E,E) 1,4-Diphenyl-1,3-butadiene formed; based on literature values, the (E,E) isomer has peaks between 6.6-7.0 ppm for vinyl protons and 7.2-7.5 ppm for the phenyl protons. Likewise, the (E,Z) isomer has vinyl proton peaks at 6.2-6.5 ppm and 6.7-6.9 ppm in addition to the phenyl protons. The H NMR in Figure 5 shows multiplets only after 6.5 ppm, again confirming that only (E,E) 1,4-Diphenyl-1,3-butadiene formed. In addition, the coupling constant J of the (E,E) isomer is around 14-15 Hz, while for the (E,Z) isomer it is 11-12 Hz. Based on the NMR in Figure 5, the coupling constant is 15.15 Hz, complementing the production of (E,E)
Using the spectrophotometer, the absorption of each sample was measured by scanning the wavelengths. After calibrating the spectrophotometer with the blank test tube, each sample was placed into the spectrophotometer and read at 360nm. Observations were continued for each pigment sample increasing the wavelength by 20nm increments. Once these absorbance values were recorded, absorption spectra for each pigment were graphed.
Fig 1: Applications of single molecule spectroscopy in solving scientific problems in Physics, Chemistry and Biology
The basic principle of the spectrophotometeric technique is the measurement of interaction between energy and electrons of the substance. Spectrophotometric technique is an analytical method used for estimating concentration of metal ion in liquid solution. One of the most magnificent effects of complex formation is the change of spectral properties. The reason for light absorption by complexes are as follows.
The purpose of this lab was to recover as much eugenol and acetyleugenol from 25 grams of cloves as possible. This lab was completed over the course of two days. The first day was dedicated to using simple distillation to collect 70 mL of distillate. The eugenol and acetyleugenol would later be recovered from the distillate. The second day was dedicated to separating the desired products from the distillate and from each other. This day was far more labor intensive and led to the completion of the lab. This lab utilized various techniques such as distillation, extraction and rotary evaporation. Separation, extraction, and recovery are key themes highlighted in this lab. Knowing where both eugenol and acetyleugenol were was vital to accomplishing
Cruntch2 – Cruntch2 is a supercomputer that allows for tests to be performed much quicker and multiple people to work at once due to the sheer force of its system. This is also where I put in my calculations after I have finish constructing the molecules and chosen what type of test I want it to run. Every command imputed on this Client, from selecting which compound file to use to executing the actual commands, is done through the Unix operating system, which is where Unix knowledge comes into play. By designating my compound that I have created and selecting a command, I can a multitude of tests, analyzations, etc. through Gaussian, a program that runs calculations on scientific compounds, using this Client. The Client connects to the school server which allows access to Gaussian, which allows for me to do my
Give an example -- how the secondary structure of proteins can be determined by CD spectroscopy. Suggest a single-molecule technique that may rely on the information about the secondary structure in order to determine the mechanical properties of a protein.
In set 1 the bond angle for ethane, propane, 2-methylprpane, and 2,2-dimethylpropane were found. One that that was noticed was that all of the values were fairly close ranging from 108-111 degrees.this may be due to the fact that the structures are similar to one another. On the other hand, because the numbers are not identical due to it being different structures it makes sense for the values to be different. In data set 2 the bond angle was observed again but instead for methyl fluoride, methyl chloride, methyl bromide, and methyl iodide. A difference that was noticed was unlike the first set the angles are all identical that being 109.5. However, both of the sets are searching for the bond angle of similar structures however this set is
Mainly IR spectroscopy has many of importance in the field of organic and inorganic chemistry. The functional group can therefore readily identified by their characteristics frequencies of absorption. This makes the IR spectroscopy the most useful means to obtain the structural information about the organic and inorganic molecules as it measure easily and quickly the atoms vibrations so in this result we are able to indentify the functional group in a molecule. When it is passed through any of organic compounds some of the radiations are absorbed by the molecules and are appeared as absorption bands while the radiations that are not absorbed are given as transmitted energy. As only those frequencies has the ability to absorb that match with the frequencies of vibration bond. So this spectroscopy sometimes also called as the vibrational spectroscopy. Absorption occurs when the molecules are excited from the ground state of level to higher state vibrational energy level. The energy in this released is given as heat energy and then the excited molecule. The IR spectroscopy is consisting of three regions:
The problem of small oscillations can be solved through the study of molecular vibrations which further, can be introduced by considering the elementary dynamical principles. The solution for the problem of small oscillations can be found out classically, as it is much easier to find its solution in classical mechanics than that in quantum mechanics. One of the most powerful tools to simplify the treatment of molecular vibrations is by use of symmetry coordinates. Symmetry coordinates are the linear combination of internal coordinates and will be discussed later in detail in this chapter.