Multistep Synthesis of Benzilic Acid from Benzaldehyde
Cambria M. Miller
March 24, 2014
Texas A&M University at Galveston, Galveston, Texas
INTRODUCTION
Benzilic acid (fig. 1) is a white crystalline solid often used in organic synthesis of certain pharmaceuticals and drugs (1). It is thought that benzilic acid may have success in anti-aging products. Benzilic acid is an alpha hydroxy acid and other alpha hydroxy acids have been used in the same manner (2).
Figure 1. Benzilic acid structure.
The purpose of this experiment was to successfully synthesize benzilic acid from benzaldehyde. Benzaldehyde is an organic molecule used to make bitter almond oil, and to synthesize many different organic compounds (3). This experiment is a multistep synthesis which means there are multiple parts that require the product of the previous step to be used as a reactant in the following step. Thus it is very critical to have high yields and accuracy at each step.
Traditionally cyanide was used as a catalyst in this reaction since Von Liebig first discovered it in his research with almond oil. However, cyanide is very poisonous and harmful to health. More recently it was discovered that Vitamin B1, a coenzyme by the name of thiamine hydrochloride may be used to catalyze the benzoin condensation, which is preferable to using cyanide. This experiment will test whether thiamine can effectively catalyze the reaction (2).
The experiment begins with the condensation of benzoin (eq. 1). In the presence of the thiamine catalyst, the 2 benzaldehyde molecules condense to produce benzoin when they are heated with sodium hydroxide and ethanol.
Equation 1: Benzoin Condensation.
The production of benzil (eq. 2) is a redox reaction. The b...
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...uced in part C using the product from part B. Another source of error was that on two different occasions recrystallization was omitted from the procedure. While this probably does not have a huge effect, crystallizing the product helps to eliminate impurities.
The overall product yield for this reaction is 90.53%. Although this number seems high, indicating a very successful synthesis, it does not account for the fact that Part C began with a new sample of benzil. Had it been continued using the product from part B, the yield would be much lower. Product may have been lost through residue being left in different glassware used due to inefficient transferring as well as reactions not running to completion. The purpose of this experiment was to produce benzilic acid, not to have high yields so in that sense there was success (excluding the formation of benzil).
The goal of this experiment is to determine which products are formed from elimination reactions that occur in the dehydration of an alcohol under acidic and basic conditions. The process utilized is the acid-catalyzed dehydration of a secondary and primary alcohol, 1-butanol and 2-butanol, and the base-induced dehydrobromination of a secondary and primary bromide, 1-bromobutane and 2-bromobutane. The different products formed form each of these reactions will be analyzed using gas chromatography, which helps understand stereochemistry and regioselectivity of each product formed.
The experiment was not a success, there was percent yield of 1,423%. With a percent yield that is relatively high at 1,423% did not conclude a successful experiment, because impurities added to the mass of the actual product. There were many errors in this lab due to the product being transferred on numerous occasions as well, as spillage and splattering of the solution. Overall, learning how to take one product and chemically create something else as well as how working with others effectively turned out to be a
Then the reaction tube was capped but not tightly. The tube then was placed in a sand bath reflux to heat it until a brown color was formed. Then the tube was taken out of the sand bath and allowed to cool to room temperature. Then the tube was shaken until a formation of a white solid at the bottom of the tube. After formation of the white solid, diphenyl ether (2 mL) was added to the solution and heated until the white solid was completely dissolved in the solution. After heating, the tube was cooled to room temperature. Then toluene (2 mL) was added to the solution. The tube was then placed in an ice bath. Then the solution was filtered via vacuum filtration, and there was a formation of a white solid. Then the product was dried and weighed. The Final product was hexaphenylbenzene (0.094 g, 0.176 mmol,
The percent yield of products that was calculated for this reaction was about 81.2%, fairly less pure than the previous product but still decently pure. A carbon NMR and H NMR were produced and used to identify the inequivalent carbons and hydrogens of the product. There were 9 constitutionally inequivalent carbons and potentially 4,5, or 6 constitutionally inequivalent hydrogens. On the H NMR there are 5 peaks, but at a closer inspection of the product, it seems there is only 4 constitutionally inequivalent hydrogens because of the symmetry held by the product and of this H’s. However, expansion of the peaks around the aromatic region on the NMR show 3 peaks, which was suppose to be only 2 peaks. In between the peaks is a peak from the solvent, xylene, that was used, which may account to for this discrepancy in the NMR. Furthermore, the product may have not been fully dissolved or was contaminated, leading to distortion (a splitting) of the peaks. The 2 peaks further down the spectrum were distinguished from two H’s, HF and HE, based off of shielding affects. The HF was closer to the O, so it experienced more of an up field shift than HE. On the C NMR, there are 9 constitutionally inequivalent carbons. A CNMR Peak Position for Typical Functional Group table was consulted to assign the carbons to their corresponding peaks. The carbonyl carbon, C1, is the farthest up field, while the carbons on the benzene ring are in the 120-140 ppm region. The sp3 hybridized carbon, C2 and C3, are the lowest on the spectrum. This reaction verifies the statement, ”Measurements have shown that while naphthalene and benzene both are considered especially stable due to their aromaticity, benzene is significantly more stable than naphthalene.” As seen in the reaction, the benzene ring is left untouched and only the naphthalene is involved in the reaction with maleic
2-ethyl-1,3-hexanediol. The molecular weight of this compound is 146.2g/mol. It is converted into 2-ethyl-1-hydroxyhexan-3-one. This compounds molecular weight is 144.2g/mol. This gives a theoretical yield of .63 grams. My actual yield was .42 grams. Therefore, my percent yield was 67%. This was one of my highest yields yet. I felt that this was a good yield because part of this experiment is an equilibrium reaction. Hypochlorite must be used in excess to push the reaction to the right. Also, there were better ways to do this experiment where higher yields could have been produced. For example PCC could have been used. However, because of its toxic properties, its use is restricted. The purpose of this experiment was to determine which of the 3 compounds was formed from the starting material. The third compound was the oxidation of both alcohols. This could not have been my product because of the results of my IR. I had a broad large absorption is the range of 3200 to 3500 wavenumbers. This indicates the presence of an alcohol. If my compound had been fully oxidized then there would be no such alcohol present. Also, because of my IR, I know that my compound was one of the other 2 compounds because of the strong sharp absorption at 1705 wavenumbers. This indicates the presence of a carbonyl. Also, my 2,4-DNP test was positive. Therefore I had to prove which of the two compounds my final product was. The first was the oxidation of the primary alcohol, forming an aldehyde and a secondary alcohol. This could not have been my product because the Tollen’s test. My test was negative indicating no such aldehyde. Also, the textbook states that aldehydes show 2 characteristic absorption’s in the range of 2720-2820 wavenumbers. No such absorption’s were present in my sample. Therefore my final product was the oxidation of the secondary alcohol. My final product had a primary alcohol and a secondary ketone
The question that was proposed for investigation was: Can the theoretical, actual, and percent yields be determined accurately (Lab Guide pg. 83)?
Results: Through a melting point reading, it was determined that the product obtained was 2,4-Dibromoanisol mp 55-58 C. The products obtained by my partners, were determined to be: (p-bromoacetanilide mp 160-165 C) and (2,4,6 tribromoaniline, mp of 108-110 C) respectively.
barbier reaction: In a 50 mL round bottom flask that had a reflux condenser attachment, saturated ammonium chloride (5 mL), THF (1 mL), zinc powder (0.4 g), benzaldehyde (0.500 mL, 0.5225 g, 4.92 mmol), and allyl bromide (0.470 mL, 0.6533 g, 5.40 mmol) were charged with stir bar and stirred at room temperature for 45 minutes. Diethyl ether (10 mL) was added to the reaction mixture and stirred. The mixture was gravity filtered into a beaker that was topped with a watchglass. The filtrate was transferred to a separatory funnel and the organic layer was extracted with deionized water (10 mL) and diethyl ether (15 mL). The organic layer was placed into an Erlenmeyer flask and the aqueous layer was placed into a beaker, which was extracted with
When benzoic acid paired with 1.0 M NaOH, it was observed that both compounds were soluble. Upon the addition of 6.0 M HCl into this solution, benzoic acid became insoluble. Benzoic acid was also insoluble in 1.0 M HCl. Ethyl 4-aminobenzoate was found to be insoluble in 1.0 M NaOH and soluble in 1.0 M HCl. But then, after adding 6.0 M NaOH into the test tube C (mixture of ethyl 4-aminobenzoate and 1.0 M HCl), a white powdery solid (undissolved compound) was formed. These demonstrate that both the acid and base became more soluble when they were ionized and less soluble when they were
Ensure gloves are worn at all times when handling strong acids and bases within the experiment of the preparation of benzocaine. 4-aminobenzoic acid (3.0g, 0.022 moles) was suspended into a dry round-bottomed flask (100cm3) followed by methylated sprits (20 cm3). Taking extra care the concentrated sulphuric acid of (3.0 cm3, 0.031 moles) was added. Immediately after the condenser was fitted on, and the components in the flask were swirled gently to mix components. It should be ensured that the reactants of the concentrated sulphuric acid and the 4-aminobenzoic acid were not clustered in the ground glass joint between the condenser itself and the flask. In order to heat the mixture to a boiling point, a heating mantle was used and then further left for gently refluxing for a constituent time of forty minutes. After the duration of the consistent forty minutes the rou...
Predictions may be made about the suitability of possible catalysts by assuming that the mechanism of catalysis consists of two stages, either of which can be first:
The process need toluene and hydrogen as a main reactor. Then, toluene and hydrogen are converted in a reactor packed with catalyst to produce benzene and methane. This reaction is exothermic and the operating conditions are 500 0C to 660 0C, and 20 to 60 bar of pressure. This process begins with mixing fresh toluene with a stream of recycle unreacted toluene, and the mixing is achieved in a storage tank. Then, the toluene is pumped to combine it with a stream of mixed hydrogen and fresh hydrogen gas. The mixture of toluene and hydrogen is preheated before it is introduce to the heater or furnace. In the furnace, the stream is heated to 600 0C, then introduced into the reactor. Basically, the main reactions occurs in the reactor.
After the some time, we filter it through a Büchner funnel before it is recrystallized and filtered again. The mass was recorded as it was dry. By adding sodium carbonate, we will now test whether what obtained is benzoic acid or not, because one can observe bobbles if it is an acid. After that we burn it to test if it is aromatic.
1) By oxidation: Aromatic acids can be obtained by the oxidation of ‘side chain’ of benzene derivatives.
The purpose of this experiment was to produce aspirin using salicylic acid and acetic acid.