Synthesis of a Liquid Crystal – Cholesteryl Benzoate Introduction The acyl chloride is a convenient reactant when undertaking ester synthesis, this is because it is highly reactive. Therefore, it can drive the reaction to completion and ensure a high yield. The high reactivity of the acyl chloride is due to the electronegative chlorine atom which pulls the electrons towards it in the C-CI bond. Furthermore, this makes the carbon atom more electrophilic and therefore easier for nucleophiles to react with. The chloride ion is a weak base and therefore acts as a good leaving group. Finally, the reaction involving an acyl chloride is irreversible, leading to the completion of the reaction and therefore the desired product, which in this case is …show more content…
In a fume cupboard using a graduated pipette, 3 mL of pyridine was added to the conical flask, followed by 0.41 mL of benzoyl chloride. The solid produced in the conical flask was yellow and had a creamy texture. The mixture was then heated on a steam bath for 10 minutes and then cooled in a beaker of ice-cold water to improve recovery and ensure full recrystallisation. A 15 mL aliquot of methanol was then added to the mixture and the solid product collected under suction filtration in a Büchner funnel. The solid was then washed with two 20 mL aliquots of methanol and then dried again under suction filtration. The solid was then further dried in a vacuum desiccator for 30 …show more content…
The melting point of transition state two was 155 – 160 °C, the sample was clear and liquid. A 0.011 g sample of cholesterol and 0.012 g sample of cholesteryl benzoate were dissolved in dichloromethane, in two separate test tubes. The dichloromethane was used as an elution solvent in the TLC procedure. A TLC was then performed on the two solutions. The results of the TLC are shown in Figure 3. Rf = distance moved by spot ÷ distance moved by the solvent front Cholesterol – Rf = 4 mm ÷ 45 mm = 0.08 Cholesteryl Benzoate - Rf = 25 mm ÷ 45 mm = 0.55 The spectrum of the product (Figure 4) was then run using an infra-red spectrometer: The peak at 710.81 cm-1 corresponds to a C-H bond (arene), this is directly attached to the ester group produced during synthesis. The peak at 1451.35 cm-1 corresponds to the C-H bond (alkyl), the alkyl groups are directly attached to the main hydrocarbon
Perhaps, a different drying agent may also be used like MgSO4. Another improvement may be to use a curved Pasteur pipette to remove the appropriate liquid. Using a test tube to add anhydrous sodium sulfate resulted in the drying agent being on the sides of the tube. Hence, to improve this error, a glass with a flat bottom may be used.
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.
As shown in figure 3, the isoborneol accounted for roughly 35.51% of the compound with a peak at 12.515, while the borneol which peaks at 12.619 accounts for roughly 8.67% of the mixture
The general objective of this experiment was for the students to familiarise with the preparation of a simple organic compound and to purify the compound by recrystallization. This experiment allows the students to conduct synthesis of aspirin, reinforcing the skills of recrystallization and the technique of melting point determination.
The IR spectrum RM-02-CC2 was obtained. The spectrum consisted of a carbonyl peak, an aromatic carbon-carbon double bond peak, and a sp2 hybridized carbon and hydrogen bond peak at 1713, 1598, and 734. These functional groups are all present in 9-flourenone. The carbonyl group specifically was important because fluorenone was the only that contained a carbonyl group. The Identity was further confirmed by the melting point, 79-80˚C. This value is similar to the known value 84˚C2. The melting point observed during the experiment is greater than the known because the sample is slightly impure. This impurity is caused by presence of fluorene on the tip of the columns. As stated before, the tip of the column needs to be manage to ensure pure products. The presence of fluorene would increase the temperature as seen in the melting point results because the melting point of this compound is greater than fluorenone. Overall, both compounds were separated with column chromatography and presented reasonable yields for both products. Column chromatography is a useful technique to separate mixtures with both large and small quantities. Unlike TLC, column chromatography and be used for large amounts of
The product that is formed the most is 1-methyl-1-cyclohexexene because it is the most highly substituted and thus the most stable, while 3-methyl-1-cyclohexene and methylenecyclohexane are produced less because they are less highly substituted and thus less stable. This reaction proceeded through an E1 pathway. In the mechanism the sulfuric acid provides a proton which protonates the hydroxyl group on the 2-methylcyclohexanol. This forms a good leaving group on the 2-methylcyclohexanol which leaves the compound as water. A carbocation results and H2PO4^- deprotonates a hydrogen on a carbon atom next to carbon atom with a positive charge resulting in alkenes with the major and minor products. One major technique used in this experiment was distillation. The reason distillation works is because different organic compounds have different boiling points. Usually a mixture containing two compounds is placed in the round bottom flask in the distillation apparatus. When the distillation apparatus is turned on and heat is applied, the vaporization of the compound in the mixture with the lower boiling point occurs. This compound, then condenses in the condenser and is received by the receiving flask at the end of the distillation
This mixture was very good at separating the mixtures because its dielectric constant is 3.832. This relatively high value for the dielectric constant gives a strong effect towards moving the compounds up the TLC plate. The way that I visualized the spots on the TLC plate is first I placed the plate under a UV light. This showed most but not all the spots. The next way was to dip the TLC plate into bromocresol green. The best mixture was mixture 5 at separating the compounds due to the greatest dielectric constant. The worst mixture being the first mixture this is due to the very low dielectric constant. The general values between the ibuprofen and the aspirin are almost the same most of the time while the naproxen is very low in
The presence of the strong peak at 1602 cm-1 supports the claim that there is an aromatic ring located in the product. Another piece of evidence to support the E1cB reaction step is the presence of the strong alkene C=C stretch (conj) located at 1628.2 ppm which supports the claim of the combination of the two reagents. Methoxy is represented in the product through the two peaks located at 1655.2 cm-1 and 1278.7cm-1 which shows that the Ketone C=O stretch (conj) and ether C-O stretch are located in the final product. Chloro is found in the product through the chlorine displayed as an alkyl halide C-Cl stretch in the product through the peak at 675.8
The percentage yield gained was 70% from the Fischer Esterification reaction, which evaluates to be a good production of yield produced as the reaction is known to be reversible where conditions such as the concentration of the reactants, pressure and temperature could affect the extent of the reaction from performing. These white crystalline crystals were tested for impurity by conducting a melting point analysis and taking spectrospic data such as the IR spectra, HNMR and CNMR to confirm the identification of the product. These spectrospic methods and melting point analysis confirmed the white crystalline crystals were benzocaine.
For the first trial, 2 dry evaporating dishes were weighed on the balance, and their masses were recorded. The first dish was 71.74 grams by mass, while the second dish was 52.03 grams by mass. We added 2 grams of unknown mixture to the first evaporating dish, and we weighted it on the balance and recorded its mass. The mass of this dish was 74.74g. Then, the first evaporating dish was put on the clay triangle using crucible tongs on the Bunsen burner in the hood area. The mixture was heated, and there was a gas that was produced which was NH4CL. After the NH4CL was removed, we took the evaporating dish using tongs and it was left to allow it to cool. After the dish was cooled down, the dish was placed on the balance and weighted again after heating (McHugh 46).
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
Next, the pH of the mixture was raised to 8 by slowly adding 10% aqueous sodium carbonate with stirring. The pH was tested using standard pH paper. The crude benzocaine product was then collected via vacuum filtration and then rinsed with 3 washes of cold diluted water. After dry, the crude product was weighed (1.35g) and transferred to a 50 mL Erlenmeyer flask with a stirbar and 20 mL of water. The mixture was then stirred while being heated to 60°C and then just enough methanol was added in order to dissolve the solid.
The butyl ethanoate ester can only be synthesised during the reflux stage. The ester will continue to be synthesised from the butanol and ethanoic acid until the point where the absence of the limiting reagent prevents further condensation from taking place. Butanol can be considered as the limiting reagent, preventing the total yield of butyl ethanoate which is obtained. Once all of the butanol has been consumed through the reaction with ethanoic acid, the reaction will continue in the reverse direction in an attempt to rejuvenate the supply of butanol. The reverse of condensation is referred to as hydrolysis, a chemical process which produces and alcohol and carboxylic acid when an ester is reacted with water in acidic conditions.
The diene and diketone has close boiling point, in order to obain pure product few time-consuming distillations are needed. This is why the next reaction in the synthesis should utilize the crude product. The product of Diels-Alder reaction can be easily purified by column chromatography. The resulting anthraquinone is reduced to hydro derivative and using the condensation with orthodiformylbenzene in the presence of Na2CO3 tetracene is obtained.
Analyze each fraction by spotting 10 times with capillary tubes on a TLC plate, which is exposed to iodine vapor for 15 minutes.