Aldol Condensation
2 March 2017
Delaney Griffin
Ron Hickman
Abstract: This experiment used Aldol Condensation, more specifically, double Claisen-Schmidt condensation in order to synthesize dibenzalacetone from benzaldehyde and acetone. In part one of the experiment, an aldol reaction occurred. In part two of the experiment, the product was recrystallized. The results concluded that the percent yield of dibenzalacetone was 82.80%. The melting point range of the product was 106.5 °C -109.3 °C due to the difficulty of boiling out the ethanol and therefore resulted in an impure solution. Overall, the experiment successfully resulted in the synthesis of dibenzalacetone, as well as, investigation of the characteristics of the product.
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During the first step of the reaction, acetone forms an enolate. An enolate ion, is “a resonance structure of the carbanion in which the negative charge is on an oxygen atom” (Kady 55). Due to the lack of an alpha hydrogen, the benzaldehyde acts as the carbonyl group. The acetone attacks the benzaldehyde and forms the aldol product. It then undergoes dehydration to result in the final product- an unsaturated ketone. Aldol condensation is an important type of organic synthesis used in a multitude of ways. The product found in this experiment, dibenzalacetone, can be useful for a variety of different things. For example, it is “commonly selected as sunscreen components based on the ability to absorb the full spectrum of UV-A radiation” (Chemicals & Chemistry).
Figure 2: The equation above shows the condensation reaction between benzaldehyde and acetone that occurs throughout the experiment in order to produce dibenzalacetone. This type of Claisen-Schmidt condensation varies from typical aldol condensation (Kady 57).
Acetone
Benzaldehyde
Ethanol
Figure 3: Above, are the chemical structures of some of the reagents used throughout the experiment.
Experimental: First, 1.5 mL of ethanol and 2 mL of 10% NaOH was placed in a test tube. In a glass vial, 0.21 g of benzaldehyde and 0.06 g of acetone were mixed. This mixture was added with a pipette in three proportions to the test tube. Between each addition, two
The objective of this lab was to create a ketone through an oxidation reaction using a using a secondary alcohol and oxidizing agent in order to use that ketone in a reduction reaction with a specific reducing agent to determine the affect of that reducing agent on the diastereoselectivity of the product. In the first part of this experiment, 4-tert-butylcyclohexanol was reacted with NaOCl, an oxidizing agent, and acetic acid to form 4-tert-butylcyclohexanone. In the second part of this experiment, 4-tert-butylcyclohexanone was reacted with a reducing agent, either NaBH4 in EtOH or Al(OiPr)3 in iPrOH, to form the product 4-tert-butylcyclohexanol. 1H NMR spectroscopy was used to determine the cis:trans ratio of the OH relative to the tert-butyl group in the product formed from the reduction reaction with each reducing agent. Thin-layer chromatography was used in both the oxidation and reduction steps to ensure that each reaction ran to completion.
Discussion: In the synthesis of 1-bromobutane alcohol is a poor leaving group; this problem is fixed by converting the OH group into H2O, which is a better leaving group. Depending on the structure of the alcohol it may undergo SN1 or SN2. Primary alky halides undergo SN2 reactions. 1- bromobutane is a primary alkyl halide, and may be synthesized by the acid-mediated reaction of a 1-butonaol with a bromide ion as a nucleophile. The proposed mechanism involves the initial formation of HBr in situ, the protonation of the alcohol by HBr, and the nucleophilic displacement by Br- to give the 1-bromobutane. In the reaction once the salts are dissolved and the mixture is gently heated with a reflux a noticeable reaction occurs with the development of two layers. When the distillation was clear the head temperature was around 115oC because the increased boiling point is caused by co-distillation of sulfuric acid and hydrobromic acid with water. When transferring allof the crude 1-bromobutane without the drying agent,
During the halogenation reactions of 1-butanol, 2-butanol, and 2-methyl-2-propanol, there is a formation of water from the OH atom of the alcohol, and the H atom from the HCl solution. The OH bond of the alcohol is then substituted with the Cl atom. Therefore all of the degrees of alcohol undergo halogenation reactions, and form alkyl halides as products. This is because the functional group of alkyl halides is a carbon-halogen bond. A common halogen is chlorine, as used in this experiment.
Salicylic acid was esterfied using acetic acid and sulfuric acid acting as a catalyst to produce acetylsalicylic acid and acetic acid. The phenol group that will attack the carbonyl carbon of the acetic anhydride is the –OH group that is directly attached to the benzene since it is more basic than the –OH group attached to the carbonyl group. This method of forming acetylsalicylic acid is an esterification reaction. Since this esterification reaction is not spontaneous, sulfuric acid was used as a catalyst to initiate the reaction. Sulfuric acid serves as the acid catalyst since its conjugate base is a strong deprotonating group that is necessary in order for this reaction to be reversible. The need for the strong conjugate base is the reason why other strong acids such as HCl is not used since its conjugate base Cl- is very weak compared to HSO3-. After the reaction was complete some unreacted acetic anhydride and salicylic acid was still be present in
In the Cannizaro reaction an aldehyde is simultaneously reduced into its primary alcohol form and also oxidized into it 's carboxylic acid form. The purpose of this experiment is to isolate, purify and identify compounds 1 and 2 which contain 4-chlorobenzaldehyde, methanol, and aqueous potassium hydroxide. Compounds 1 and 2 are purified by crystallization. . The purified product will be characterized by IR spectroscopy and melting point.
Abstract: Using hypochlorous acid to convert secondary alcohol called cyclododecanol to the corresponding ketone which is cyclododecanone by oxidation.
Purpose: The purpose of this experiment is to observe a variety of chemical reactions and to identify patterns in the conversion of reactants into products.
6. Purpose: to clarify the mechanism for the cycloaddition reaction between benzonitrile oxide and an alkene, and to test the regiochemistry of the reaction between benzonitrile oxide and styrene; to purify the crude product of either trans-stilbene, cis-stilbene, or styrene reaction.
A small beaker was placed under the arm of the distillation head to catch the distillate. Foil was wrapped around the neck of the round-bottomed flask and a wet paper towel was wrapped around the arm of the distillation head to create a condenser. The flask was heated gently so that the distillate dropped at a rate of two drops per minute. The temperature was recorded as every drop was collected. The distillation began at around 55.0 ℃. The distillation was stopped after 29 drops were collected to prevent the solution from being distilled to dryness. See attached data. The known boiling point of 1-butanol is 117.5 ℃ (Lemonds). The known boiling point of 1-propanol is 97 ℃ (Thiyagarajan). The known boiling point of acetone is 56 ℃ (Forss). The known boiling point of 2-butanone is 79.6 ℃ (Jiang). For unknown #3 the boiling point of the first substance seemed to be around 56 ℃ and the boiling point of the second substance seemed to be around 111 ℃. Therefore unknown #3 seemed to be a mixture of acetone and 1-butanol.
In this experiment, 0.31 g (2.87 mmol) of 2-methylphenol was suspended in a 10 mL Erlenmeyer flask along with 1 mL of water and a stir bar. The flask was clamped onto a hotplate/stirrer and turned on so that the stir bar would turn freely. Based on the amount of 2-methylphenol, 0.957 mL (0.00287 mmol) NaOH was calculated and collected in a syringe. The NaOH was then added to the 2-methylphenol solution and allowed to mix completely. In another 10 mL Erlenmeyer flask, 0.34 g (2.92 mmol) of sodium chloroacetate was calculated based on the amount of 2-methylphenol and placed into the flask along with 1 mL of water. The sodium chloroacetate solution was mixed until dissolved. The sodium chloroacetate solution was poured into the 2-methylphenol and NaOH solution after it was fully dissolved using a microscale funnel.
The purpose of this lab was to carry out a dehydration reaction of 2-methylcyclohexanol by heating it in the presence of phosphoric acid and determining which alkene product would be the major product. Methylcyclohexanols were dehydrated in an 85% phosphoric acid mixture to yield the minor and major alkene product by elimination reaction, specifically E1. The alkenes were distilled to separate the major and minor products and gas chromatography was used to analyze the results and accuracy of the experiment. The hypothesis was the major product of the reaction would be the most substituted product. This conclusion was made because of
In this experiment, the main objective was to synthesize a ketone from borneol via an oxidation reaction and secondly, to produce a secondary alcohol from camphor via a reduction reaction. Therefore, the hypothesis of this lab is that camphor will be produced in the oxidation reaction and isoborneol will be the product of the reduction reaction because of steric hindrance. For the oxidation step, a reflux will be done and then a microscale reflux for the reduction step. The products will be confirmed using Infrared spectroscopy, the chromic acid test, 2,4-DNP test and 13C NMR spectroscopy. The results of this
In this laboratory experiment a synthesis was performed through several separate steps. The purpose of the experiment was to synthesize tetraphenylcyclopentadienone from benzaldehyde and to run reactions on carbonyl containing compounds. There was a total of three steps that led up to the synthesis of the final product, tetraphenylcyclopentadienone. The first step of the experiment was the condensation of benzaldehyde to yield benzoin. Thiamine catalyst along with water and ethanol were added to the benzaldehyde, then NaOH was added until the solution turned yellow. After recrystallization, the product was benzoin. Step two was the oxidation of benzoin to benzil.
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 overall goal in this lab was to oxidize borneol, a secondary alcohol, into camphor, which is a ketone. For the purposes of oxidation chromic acid was utilized, which was prepared by adding a 1:1 ratio of chromium trioxide to dilute sulfuric acid.