Resacetophenone Synthesis Lab Report

The design of this experiment aimed to synthesize 2-methylphenoxyacetic acid from 2-methylphenol and sodium chloroacetate by means on phenol alkylation. 2-Methylphenoxyacetic acid has been used to control the growth in plants and exemplifies a product of synthesis as it is a complex molecule constructed from two simple molecules. This synthesis proceeds by a nucleophilic substitution reaction, more specifically, via SN2 mechanism (see below). An SN2 mechanism's reactants are a nucleophile and a good leaving group (usually a halide ion). Once the crude product is obtained, it is purified by recrystallization with water and collected.

This lab could have contained errors. The errors could have happened when performing the lab. Some of the possible errors in this lab are:

The following equations and calculations are necessary in order to assess the results of the experiment. Calculation 1 utilizes Eq.1 to determine the mass and actual yield of triphenylmethanol on a watch glass. In all of the following calculations, “LR” refers to benzophenone, the limiting reagent of the experiment, and “Product” refers to triphenylmethanol.

Grignard reagents cannot be synthesized from alcohols because instead of reacting with the halide to form the Grignard reagent, the alcohol is deprotenated. Grignard reagents also cannot be synthesized from molecules with a carbonyl group.

The purpose of this experiment was to perform a nucleophilic substitution reaction to construct a biologically active compound from two simple parts and then to recrystallize the product collected, which is a purification technique that purifies solids based on differences in solubility. In order to accomplish this, other techniques such as heating at reflux, and suction filtration were used. Heating at reflux is a technique used in lab that allows a solution to be heated for a certain amount of time once it begins boiling. Suction filtration is a separation technique that is combined with a water aspirator and was used to collect the product from this experiment, which was 2-methylphenooxyacetic acid.

The compound aquapentaamminecobalt(III) Nitrate, [Co(NH3)5OH2] NO3, is a metal complex bonded to the molecule nitrate to attain a neutral charge. The synthesis of this molecule is a more complex one, requiring the recrystallization of an intermediate species. When the complex has been formed and isolated via filtration, the complex can be reacted with various aqueous solutions, one being dimethyl sulfoxide, C2H6OS. When reacted these reagents form the compound Co(NH3)5(OS(CH3)2)3+, H2O, and NO3-, though not inn this ratio. Specifically the aquapentaamminecobalt(III) molecule can be used to study the sixth coordination site on the molecule where the later is bound. Because of the weaker bond between the cobalt ion and the water

After putting the CH2Cl2 to a beaker containing the drying agent anhydrous sodium sulfate, a sticky white solid was recovered.

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.

To prepare and purify an ester: 1-pentyl ethanoate, using pent-1-ol and ethanoic acid. An annotated reaction showing this reaction is shown below:

After the initial mixture has refluxed, 9.11 grams of benzophenone was dissolved in 100 mL of anhydrous ether in a beaker and was then transferred into the separatory on the reflux apparatus. This solution was then added to the Grignard reagent at a drop wise rate while stirring. After the benzophenone was added, the mixture was then refluxed for 15 minutes on a heating mantle.

In this experiment, a nucleophilic substitution was performed, where a chloride nucleophile substituted a tertiary hydroxyl group on 2-methyl-2-butanol. In a nucleophilic substitution reaction, an electron rich nucleophile attacks a positively or partially positively charged electrophile, and replaces a leaving group. In this reaction, chloride ions are the nucleophile, the tertiary carbon in 2-methyl-2-butanol is the electrophile, and water is the leaving group. In the mechanism for this reaction, the oxygen from the hydroxyl group of the 2-methyl-2-butanol attacks the hydrogen of the HCl, causing heterolytic cleavage of the HCl, resulting in a chloride ion, and in the oxygen bonding to an extra hydrogen, and becoming positively charged.

The product attained was a white, dry solid. The small amount of product lost during the second recrystallization was most likely do to impurities, which were filtered away with the methanol. Impurities that contributed to the low percent yield could be due to side reactions such as methyl o-nitrobenzoate and methyl p-nitrobenzoate. Although the percent yield attained was low, the product attained was fairly pure due to similarity in melting point and IR spectrum compared to standardly accepted values for methyl m-nitrobenzoate.

An ice bath was prepared in a large beaker and a small cotton ball was obtained. 0.5 g of acetanilide, 0.9 g of NaBr, 3mL of ethanol and 2.5 mL acetic acid was measured and gathered into 50mL beakers. In a fume hood, the measured amounts of acetanilide, NaBr, ethanol and acetic acid were mixed in a 25mL Erlenmeyer flask with a stir bar. The flask was plugged with the cotton ball and placed in an ice bath on top of a stir plate. The stir feature was turned on a medium speed. 7mL of bleach was obtained and was slowly added to the stirring flask in the ice bath. Once all the bleach was added, stirring continued for another 2 minutes and then the flask was removed from the ice bath and left to warm up to room temperature. 0.8mL of saturated sodium thiosulfate solution and 0.5mL of NaOH solution were collected in small beakers. The two solutions were added to the flask at room temperature. The flask was gently stirred. Vacuum filtration was used to remove the crude product. The product was weighed and a melting point was taken. The crude product was placed into a clean 25mL Erlenmeyer flask. A large beaker with 50/50 ethanol/water

Recrystallization is a technique frequently used in organic chemistry to purify solid organic compounds. The goal of this technique is to allow organic compounds to form crystal lattice structures, and to remove any of the impurities that do not align within this crystal structure.1 The theory behind recrystallization revolves around entropy; as heat will cause a organic compound to dissolve (increase in entropy), a decrease in heat will then allow that organic compound to reform (decrease in entropy) and become purer.2

Samples of benzophenone, malonic acid, and biphenyl were each tested with water, methyl alcohol, and hexane. Benzophenone was insoluble in water as it is nonpolar while water is highly polar. Benzophenone was soluble in methyl alcohol, dissolving in 15 seconds, because methyl alcohol is intermediately polar as benzophenone is nonpolar. Methyl alcohol is polar but not as much as water. Thus, the nonpolar benzophenone was soluble in methyl alcohol. Benzophenone was partially soluble in hexane because hexane is nonpolar as is benzophenone. Thus, benzophenone was dissolved in hexane. Malonic acid was soluble in water because both malonic acid and water are polar. It took 25 seconds for malonic acid to dissolve in water. Malonic acid was soluble in methyl alcohol because malonic acid is polar and methyl alcohol is intermediately polar, allowing malonic acid to dissolve in the methanol in 15 seconds. Malonic acid was insoluble in hexane because hexane is nonpolar while malonic acid is polar. Biphenyl was insoluble in water as water is highly polar whilst biphenyl is nonpolar. Biphenyl was partially soluble in methanol which is intermediately polar whilst biphenyl is nonpolar, allowing it to dissolve a little. Biphenyl was soluble in hexane because both biphenyl and hexane are nonpolar molecules. Biphenyl dissolved in hexane in 10 seconds.