Esmeralda Curiel Organic Chemistry November 11, 2014 Experiment 62 – The Aldehyde Enigma INTRODUCTION 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. As detailed in Pavia 's Organic Laboratory techniques the reaction is expected to proceed via the following reaction: Aqueous …show more content…
For the organic layer, we had a melting point range of 240-243°C. For the IR spectra, we did note the C-Cl bond although there was not an OH bond present. ANALYSIS The reaction involves a nucleophilic acyl substitution on an aldehyde, with the leaving group concurrently attacking another aldehyde in the second step. First the Potassium hydroxide attacks a carbonyl, which forms a tetahedral intermediate which then collapses when attacked by another hydroxide. The carbonyl is formed again when its hydride attacks another carbonyl. In the final step of the reaction, the acid and alkoxide ions formed exchange a proton. In the presence of a very high concentration of base, the aldehyde first forms a doubly charged anion from which a hydride ion is transferred to the second molecule of aldehyde to form carboxylate and alkoxide ions. Subsequently, the alkoxide ion acquires a proton from the solvent. 4- chlorobenzoic acid which was the aqueous layer has a theoretical melting point of 240-243°C, the organic layer, 4-chlorobenzyl alcohol has a theoretical melting point of 68-71°C. During our experiment we were unable to collect any data for the organic
After each of the solids were completely dry, each was placed into a MelTemp device. The temperature at which each solid began to melt and completed melting was recorded.
The sodium hydroxide acts to pull the hydrogen off the oxygen in the 2-methylphenol so that the oxygen has a negative charge and can attack the sodium chloroacetate. Again, using a 1:1 molar ratio, 0.34 g (2.9 mmol) of sodium chloroacetate (the good leaving group) was added to 1 ml of water and dissolved. Following dissolving all of the 2-methylphenol (to avoid the sodium hydroxide reacting concurrently with the sodium chloroacetate and 2-methylphenol) in the sodium hydroxide, the aqueous solution of sodium chloroacetate was transferred to the reaction flask. This mixture was then heated to reflux, using a medicine dropper affixed to the top of the flask as an alternative method to boil without
Abstract: Using hypochlorous acid to convert secondary alcohol called cyclododecanol to the corresponding ketone which is cyclododecanone by oxidation.
Though the products had dissimilar melting point values, it is not enough to conclude that they are different. To be certain of the identity of the products, Infrared Spectroscopy (IR) and H- NMR were used. While IR is used to determine the functional groups present in an unknown substance through identification of covalent bonds, H-NMR is used to determine the structure of an unknown compound. The IR from both products had peaks at almost identical frequencies. The IR of both
The melting point range of the unknown acid is most similar to the mixed range of the unknown acid and 2-chlorobenzoic acid, so the unknown acid is 2-chlorobenzoic acid.
Objective: The objective of this experiment is to use acid-base extraction techniques to separate a mixture of organic compounds based on acidity and/or basicity. After the three compounds are separated we will recover them into their salt forms and then purify them by recrystallization and identify them by their melting points.
Discussion: As seen in the melting point determination, the average melting point range of the product was 172.2-185.3ºC. The melting points of the possible products are listed as 101ºC for o-methoxybenzoic acid, 110ºC for m- methoxybenzoic acid, and 185ºC for p- methoxybenzoic acid. As the melting point of the sample
Identifying this organic acid was an extensive task that involved several different experiments. Firstly, the melting point had to be determined. Since melting point can be determined to an almost exact degree, finding a close melting point of the specific unknown can accurately point to the identification of the acid. In this case the best melting point
The reaction took place in a conical vial and .2mL of each of the reactant samples were added to it along with some 95% ethanol. Two drops of NaOH were added shortly after and stirred at room temperature for fifteen minutes. The vial was cooled in and ice bath and crystallized. Vacuum filtration was performed to filter the crude product. The crude product was recrystallized using methanol and filtered again. We made one change to the procedure and instead of using .7mL of ethanol we
First, the normalized freezing points for unknowns 3 and 4 were -2.8 degrees Celsius and -3.0 degrees Celsius, respectively. The van’t Hoff factor was one because the solid does not break apart, and it remains as one particle. The molalities were 1.505 mol/kg for unknown 3 and for unknown 4 it was 1.613 mol/kg. In the second step, the unknown number of moles of each unknown was determined by using molality. This was calculated by dividing the molality determined in step one by 20 mL of water solvent.
The melting points were 132.1C-136.4C (for urea), 132.1C-135.3C (for trans-cinnamic acid), and 99.2C-129.8C (for the 50-50 mixture). While observing the compounds in the apparatus, the 50-50 mixture melted at a lower temperature and rate as opposed to urea and the trans-cinnamic acid. Urea and trans-cinnamic acid held narrow ranges such as 4.3 and 3.2 while the 50-50 mixture held a wider range of 30.6. According to “Melting Points,” published by Kathleen Armstrong, “Melting points are sensitive to the purity of the organic compound, since the crystal lattice of the compound is disrupted by the presence of an impurity (2009). ”
phenylalanine) replaced Ala with more hydrophilic Gly, resulting in can be seen in the figure to
Two molecules of formaldehyde react with one molecule of alkali. One molecule is reduced to methyl alcohol and the other is oxidized to formic acid. This reaction is called Cannizzaro's reaction. [5]
This modification is similar to a standard Wittig reaction in that the first step, which has already been done for you, is the reaction of a trialkyl phosphite with a suitable alkyl halide as shown below in two steps:
The objectives of this lab are, as follows; to understand what occurs at the molecular level when a substance melts; to understand the primary purpose of melting point data; to demonstrate the technique for obtaining the melting point of an organic substance; and to explain the effect of impurities on the melting point of a substance. Through the experimentation of three substances, tetracosane, 1-tetradecanol and a mixture of the two, observations can be made in reference to melting point concerning polarity, molecular weight and purity of the substance. When comparing the two substances, it is evident that heavy molecule weight of tetracosane allowed