Name: Megan Coghlan
Lab Section: S343, Wednesday, 12:15 PM
Date: September 17, 2015
Purification of Biphenyl
Results
Methanol, acetone, dichloromethane, toluene, and hexanes were tested for their miscibility with water. Methanol and acetone were found to be miscible with water, and dichloromethane, toluene, and hexanes were immiscible. Two layers—one organic and one aqueous—were observed each time an immiscible solvent was combined with water. Dichloromethane was observed as the bottom layer, and toluene and hexanes were observed as the top layers when added to test tubes of water. In Table 1 below, density, boiling point, and miscibility with water are shown for the organic solvents used in this experiment.1
Table 1: Miscibility with Water Test
Solvent
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Miscible with Water Density (g/mL at 25°C) Layer (top or bottom) Boiling Point °C Methanol Yes 0.792 --- 64.7 Acetone Yes 0.791 --- 56.0 Dichloromethane No 1.325 Top 39.6 Toluene No 0.867 Bottom 110.6 Hexanes No 0.655 Bottom 68.0 The solubility of biphenyl with each organic solvent at room temperature is shown in Table 2.
Biphenyl was fully soluble in dichloromethane at room temperature and partially soluble in hexanes. Biphenyl was insoluble in methanol, acetone, toluene, and hexanes at room temperature but soluble near their respective boiling points. At room temperature and at 100°C, biphenyl was insoluble in water. Biphenyl recrystallized out from hexanes and methanol at room temperature but remained dissolved in acetone and toluene.
Table 2: Solubility and Recrystallization Observations
Solvent Solubility of Biphenyl at Room Temperature
Solubility of Biphenyl near Boiling Point
Recrystallization Upon Cooling?
Methanol Insoluble Soluble Yes
Acetone Insoluble Soluble
No Dichloromethane Soluble --- --- Toluene Insoluble Soluble No Hexanes Partially Soluble Soluble Yes Water Insoluble Insoluble --- Hexanes were chosen as the solvent for recrystallization of biphenyl.2 Crude biphenyl was recrystallized in hexanes then isolated by suction filtration. The crude biphenyl was brown and grainy in appearance, and the recrystallized biphenyl that was formed consisted of clear/white crystals. The initial biphenyl mass was 0.502 grams, the mass of the recrystallized biphenyl was 0.294 grams. Consequently there was a 58.6% recovery of biphenyl. The percent recovery was determined using Calculation 1. Calculation 1 (Mass of purified biphenyl)/(Mass of impure biphenyl)×100=% Recovery Pure biphenyl and crude biphenyl were prepared for thin layer chromatography (TLC) in hexanes, ethyl acetate, and 4:1 hexanes: ethyl acetate. The TLC data for biphenyl with hexanes is shown in Figure 1. Pure biphenyl was spotted on the left, and crude biphenyl was spotted on the right. The Rf value for both of the two spots observed was 0.44. Figure 2 shows the resulting chromatogram when ethyl acetate was used for TLC of pure biphenyl (left spot) and crude biphenyl (right spot). The Rf value was 0.70 for both pure and crude biphenyl. A 4:1 ratio of hexanes to ethyl acetate was used for the third TLC and is shown in Figure 3. The pure biphenyl (left spot) had an Rf value of 0.55, while the crude biphenyl (right spot) had an Rf value of 0.52. The chromatograms were viewed under short-wavelength ultraviolet light. Figure 1: TLC of Biphenyl in Hexanes Figure 2: TLC of Biphenyl in Ethyl Acetate Figure 3: TLC of Biphenyl in 4:1 Hexanes: Ethyl Acetate The 4:1 ratio of hexanes: ethyl acetate was chosen as the eluent for column chromatography. Fifty milligrams of the recrystallized biphenyl was purified using column chromatography. One-milliliter fractions of biphenyl-containing eluent were taken from column chromatography until all of the biphenyl had emerged from the column, leaving the remainder of fractions as just the eluent. TLC was used to test the fractions for biphenyl. The sixth fraction taken from column chromatography contained no biphenyl. Figure 4 shows fractions 1 (left) and 4 (center) alongside pure biphenyl (right). Figure 5 shows fractions 5 (left) and 6 (center) next to pure biphenyl (right). Fraction 6 did not contain biphenyl and therefore did not show any spots in the TLC test. Figure 4: TLC Test for Biphenyl in Fraction 4 Figure 5: TLC Test for Biphenyl in Fraction 6 The fractions that did contain biphenyl were poured into a pre-weighed watchglass. The eluent was evaporated off, and the mass of purified biphenyl was recorded as 49 mg. Starting with 50 mg of recrystallized biphenyl and finishing with 49 mg of column purified biphenyl, the percent recovery from the column chromatography method was 98%, determined using Calculation 1. Melting point data was taken for impure biphenyl, recrystallized biphenyl, and column purified biphenyl. The results are shown in Table 3. The melting point1 of pure biphenyl is 69.2°C. Impure biphenyl displayed a melting range of 1.4°C, the largest of the three ranges. Column purified biphenyl exhibited a 0.3°C melting range. Each of the three solids began to melt before reaching 69.2°C, the actual melting point of pure biphenyl. Table 3: Melting Point Data Solid Melting Range (°C) Impure Biphenyl 68.0-69.4 Recrystallized Biphenyl 68.6-69.2 Column Purified Biphenyl 69.0-69.3 TLC data was taken for authentic biphenyl, impure biphenyl, recrystallized biphenyl, and column purified biphenyl. The results are shown in Figure 6. A 4:1 ratio of hexanes to ethyl acetate was used as the TLC solvent. Authentic biphenyl (left) exhibited an Rf value of 0.70. Impure biphenyl (center left) had an Rf value of 0.62, ad recrystallized biphenyl had an Rf value of 0.66. The Rf value for column purified biphenyl was 0.68. Figure 6: TLC of Variable Purity Biphenyl Samples Discussion Of the organic solvents tested, methanol and acetone were water-soluble, while dichloromethane, toluene, and hexanes were water-insoluble. Dichloromethane is moderately polar, yet does not participate in hydrogen bonding and thus is immiscible with water. Hexanes and toluene are both nonpolar organic solvents and were not expected to be miscible with water. Methanol is small alcohol, and acetone is a small carbonyl. Both solvents are polar and were expected to be miscible with water. Based on the structure of biphenyl, shown in Figure 7, biphenyl was expected to be soluble in hexanes, dichloromethane, and toluene at room temperature. Biphenyl was fully soluble in dichloromethane at room temperature, partially soluble in hexanes, and insoluble in toluene. These results are likely due to a laboratory error in the solute to solvent ratio. Had more solvent been added, biphenyl would have likely dissolved in each of the three nonpolar organic solvents at room temperature. Once heated to their respective boiling points, biphenyl was fully soluble in hexanes and toluene. Based on theory, biphenyl should have dissolved in dichloromethane, toluene, and hexanes without the addition of heat. Figure 7: Structure of Biphenyl Hexanes were selected as a suitable solvent2 for recrystallization of biphenyl, because biphenyl was partially soluble in hexanes at room temperature and fully soluble near 68.0 °C, the boiling point of hexanes1. Oiling out was prevented, because the melting point of biphenyl1 was higher than the boiling point of hexanes1. Acetone could have been selected as a suitable solvent had it recrystallized back out upon cooling. The biphenyl recrystallized back out only from hexanes and methanol. Methanol’s boiling point1 is lower than hexane’s1, and oiling out could have been avoided with larger certainty. Biphenyl was completely insoluble in methanol at room temperature but partially soluble in hexanes, suggesting methanol may have been the better solvent to use. Methyl orange dye, an impurity, was soluble in methanol (Pre-Lab). At room temperature, methyl orange would have dissolved in methanol, and the biphenyl could have been separated from the solvent-impurity mixture based on its nonpolar character. In a future experiment, methanol may serve as the better solvent2. Methyl orange is polar; it is highly conjugated and contains multiple hydrogen bond acceptors as well as an ionic bond between sodium and oxygen. Based on its structure shown in Figure 8, methyl orange was expected to be insoluble in hexanes. When hot hexanes were added to the crude product, the nonpolar pure biphenyl was expected to be soluble in hexanes, allowing the polar methyl orange dye to be removed. Figure 8: Structure of Methyl Orange Recrystallization of biphenyl was relatively ineffective in terms of percent recovery (Results). The biphenyl crystals were difficult to transfer from the 125 mL sidearm flask to a small beaker. A large portion was visibly left in the sidearm flask following the transfer. In future experiments, glassware should be chosen with greater care. Column purification was significantly more effective than recrystallization in terms of percent recovery (Results). A 4:1 ratio of hexanes:ethyl acetate was chosen for the column chromatography eluent, because it was the only solvent to differentiate among pure and crude biphenyl during the TLC tests (Figures 1-3). Compared to the Rf value for recrystallized biphenyl, the Rf value for column purified biphenyl was closer to the Rf value for authentic biphenyl (Figure 6), indicating that the recrystallized biphenyl was less pure than the column purified biphenyl.3 Melting point data also shows that the column purified biphenyl was more pure than the recrystallized biphenyl. A large melting point range suggests an impure sample.4 Recrystallized biphenyl exhibited a larger melting range than did column purified biphenyl (Results). Additionally, the temperature at which recrystallized biphenyl began to melt was lower than that of column purified biphenyl (Results), which serves as another indicator of impurity.3 Based on class data, column chromatography served as the more effective method3 for purification of biphenyl. The data showed a higher average percent recovery from column chromatography as well as a smaller melting point range. Within the class data, the selected recrystallization solvent varied from group to group, yet purity and percent recovery results were consistent in determining column chromatography as the more effective method at this scale. While a more suitable solvent for recrystallization may have improved the purity and yield of the biphenyl sample produced, the effect would have likely been marginal compared to the notably superior results from column chromatography. Column chromatography also proved to be a more efficient purification method, as the recrystallizing process was time-consuming. On the other hand, more solvent was used for column chromatography, and thus more waste was produced. Recrystallization of biphenyl produced a small amount of waste and therefore would be beneficial to utilize as a method for purifying biphenyl on a large scale. In fact, loss of product often results when too much solvent is added during the recrystallization process (further minimizing waste).5 If time is not a concern and the solvent or solvent system has been carefully chosen, recrystallization can produce extremely pure samples. Deciding to purify using recrystallization or column chromatography largely depends on the solvents available as well as the intended scale of production. Conclusion Recrystallization and column chromatography both proved as effective methods for purifying biphenyl. Column chromatography produced better results, but these may have been the outcome of an unsuitable solvent choice for the recrystallization portion of the experiment. References
The goal of this two week lab was to examine the stereochemistry of the oxidation-reduction interconversion of 4-tert-butylcyclohexanol and 4-tert-butylcyclohexanone. The purpose of first week was to explore the oxidation of an alcohol to a ketone and see how the reduction of the ketone will affect the stereoselectivity. The purpose of first week is to oxidize the alcohol, 4-tert-butylcyclohexanol, to ketone just so that it can be reduced back into the alcohol to see how OH will react. The purpose of second week was to reduce 4-tert-butylcyclohexanol from first week and determine the effect of the product's diastereoselectivity by performing reduction procedures using sodium borohydride The chemicals for this lab are sodium hypochlorite, 4-tert-butylcyclohexanone
Alcohol, which is the nucleophile, attacks the acid, H2SO4, which is the catalyst, forming oxonium. However, the oxonium leaves due to the positive charge on oxygen, which makes it unstable. A stable secondary carbocation is formed. The electrons from the conjugate base attack the proton, henceforth, forming an alkene. Through this attack, the regeneration of the catalyst is formed with the product, 4-methylcyclohexene, before it oxidizes with KMnO4. In simpler terms, protonation of oxygen and the elimination of H+ with formation of alkene occurs.
In this lab 4-tert-butylcyclohexanone is reduced by sodium borohydride (NaBH4) to produce the cis and trans isomers of 4-tert-butylcyclohexanol. Since the starting material is a ketone, NaBH4 is strong enough to perform a reduction and lithium aluminum hydride is not needed. NaBH4 can attack the carbonyl group at an equatorial (cis) or axial (trans) position, making this reaction stereoselective. After the ketone is reduced by the metal-hydride, hydrochloric acid adds a proton to the negatively charged oxygen to make a hydroxyl group. The trans isomer is more abundant than the cis based on the results found in the experiment and the fact that the trans isomer is more stable; due to having the largest functional groups in equatorial positions.
The boiling point of the product was conducted with the silicone oil. Lastly, for each chemical test, three test tubes were prepared with 2-methylcyclohexanol, the product, and 1-decene in each test tube, and a drop of the reagent were added to test tubes. The percent yield was calculated to be 74.8% with 12.6g of the product obtained. This result showed that most of 2-methylcyclohexanol was successfully dehydrated and produced the product. The loss of the product could be due to the incomplete reaction or distillation and through washing and extraction of the product. The boiling point range resulted as 112oC to 118oC. This boiling point range revealed that it is acceptable because the literature boiling point range included possible products, which are 1-methylcyclohexene, 3-methylcyclohexene, and methylenecyclohexane, are 110 to 111oC, 104oC, and 102 to 103 oC. For the results of IR spectroscopy, 2-methylcyclocahnol showed peaks at 3300 cm-1 and 2930 cm-1, which indicated the presence of alcohol and alkane functional group. Then, the peak from the product showed the same peak at 2930 cm-1 but the absence of the other peak, which indicated the absence of the alcohol
In order to separate the mixture of fluorene, o-toluic acid, and 1, 4-dibromobenzene, the previously learned techniques of extraction and crystallization are needed to perform the experiment. First, 10.0 mL of diethyl ether would be added to the mixture in a centrifuge tube (1) and shaken until the mixture completely dissolved (2). Diethyl ether is the best solvent for dissolving the mixture, because though it is a polar molecule, its ethyl groups make it a nonpolar solvent. The compounds, fluorene and 1, 4-dibromobenzene, are also nonpolar; therefore, it would be easier for it to be dissolved in this organic solvent.
In a separate beaker, acetone (0.587 mL, 8 mmol) and benzaldehyde (1.63 mL, 16 mmol) were charged with a stir bar and stirred on a magnetic stirrer. The beaker mixture was slowly added to the Erlenmeyer flask and stirred at room temperature for 30 minutes. Every 10 minutes, a small amount of the reaction mixture was spotted on a TLC plate, with an eluent mixture of ethyl acetate (2 mL) and hexanes (8 mL), to monitor the decrease in benzaldehyde via a UV light. When the reaction was complete, it was chilled in an ice bath until the product precipitated, which was then vacuum filtrated. The filter cake was washed with ice-cold 95% ethanol (2 x 10 mL) and 4% acetic acid in 95% ethanol (10 mL). The solid was fluffed and vacuum filtrated for about 15 minutes. The 0.688 g (2.9 mmol, 36.8%, 111.3-112.8 °C) product was analyzed via FTIR and 1H NMR spectroscopies, and the melting point was obtained via
As shown in figure 2, the percentage of each isomeric alcohol in the mixture had been determined. The hydrogen atom on the carbon atom with the hydroxyl group appear at around 4.0 ppm for borneol and 3.6 ppm for isoborneol. The product ratio has been determined by integrating the peaks. A ratio of 6:1 for the Isoborneol/borneol ratio was expected and is validated by the calculations shown above, with isoborneol percentage at 83.82% and 16.17% of borneol. A CHCl3 group noted at around 7ppm and a CH2Cl2 at around 3.5ppm.
When the flame was blown out and the glowing wooden splint was placed halfway into the test tube containing H2O2 and MnO2 crystals, the splint reignited and caught flame once again. This demonstrates the decomposition of H2O2 into water and hydrogen. MnO2 is a catalyst that increases the rate at which H2O2 decomposes. Adding oxygen to a fire will cause it to burn faster and hotter and the oxygen rich test tube allowed the splint to reignite.
Methionine represents the first limiting amino acid in broiler nutrition, thus different sources are available to balance diets based of corn and soybean. Bioavailability is different for each methionine source because of its rate of absorption and metabolic pathways. A broiler experiment was conducted to determine the relative bioavailability of Hydroxyl Methyl Analog Calcium (HMA-Ca) relative to DL-Methionine(DL-Met). The experiment was conducted at at Lavinesp (Unesp, Jaboticabal). It was used 1890 male broiler Cobb 500 of 21 days old, they were weighted and distributed homogeneously in a complete randomized design with 13 treatments and 7 replicates each. All birds fed either a basal diet deficient in sulphur amino acids, digestible methionine and cysteine (dig Met+Cys), or the basal diet with four levels of HMA-Ca (0.063, 0.183, 0.302 and 0.540%) and DL-Met (0.054, 0.156, 0.259 and 0.463%) to achieve increasing levels of dig Met+Cys. For the analysis, 5% of significance was considered and procedures of non-linear model were used by SAS. Exponential regression determinates bioavailability of HMA-Ca relative to DL-Met by calculating the relation of the slope of HMA-Ca relative to DL-Met
Performing this experiment, we used the technique called Acid-Base extraction to isolate Eugenol, which is one of the main ingredients of clove oil. Acid-Base extraction is the most efficient method for isolating organic component; it is efficient because it purifies the acid and base mixture based on their chemical identities. We have seen throughout this experiment that acid and base play an important role, when it comes to solubility in water. Our basic knowledge of acid and base is acid is a proton donor and base is a proton acceptor. This ideology helps us to understand why organic compounds are not soluble in water. When compounds tend to be insoluble, we have to use acid and base reaction, to change its solubility. The changes that occurred
1-Butanol with intermediate polarity was soluble in both highly polar water and non polar hexane as 1-butanol can be either polar or non polar compound. 1-Butanol was polar based on the general rule of thumb stated that each polar group will allow up to 4 carbons to be soluble in water. Also, 1-butanol can be non polar due to their carbon chains, which are attracted to the non polarity of the hexane.
Methanol and Ethanol have differences as Methanol melts at a higher temperature and boils at a lower temperature than Ethanol. Higher alcohols, which include Butanol and Propanol, have a higher molecular weight and this is why Butanol is used in perfumes. Ethanol, which is sugar based, with its low freezing point, has a specific use as an antifreeze for cars and other vehicles. GRAPH Tripod Matches Goggles Method: To begin with, I choose one of the four different alcohols. I weigh beforehand in the spirit burner.
However, the polarities should not be the same as this will cause the compound to completely dissolve in the solvent (1). The second procedure dealt with finding a suitable solvent to recrystallize the crude acetanilide. A sand bath was set up and 0.5 mL of each solvent was added to 50 mg of acetanilide in four different test tubes. The four solvents used to test the solubility of the acetanilide were water, ethanol, dichloromethane and hexanes.
Almost every molecule in a solid moves, but it’s called a solid mainly because all of the molecules are very compacted and don’t have a lot of room to move.
The solubility of a substance is defined as its ability to dissolve. There are some factors that alter solubility, such as pressure and the type of solvent, but will temperature affect the solubility of a substance? The investigation problem is to identify whether or not the temperature of a substance affects its ability to dissolve in another substance. Understanding solubility and the processes that undergo is very important, this is due to the important role that it plays in our daily life as well as in the human body. When it comes to oral ingestion, especially in drug delivery, it is profitable since it permits to deliver the medicine throughout the system in order to gain positive and desired responses. Meanwhile it is seen in the human body, it is also manifested while doing household cleaning and in automoviles. That’s why it is essential to recognize and know what is solubility in order to be able to control, manipulate, and enhance it as well as get informed of how life works by depending on water and chemical reactions.