Recrystallization Synthesis

The reaction was refluxed under nitrogen gas for overnight and completion was checked by the TLC (Ethylacetate: hexane; 2:3). The reaction mass was cooled to RT. Then the solvent was completely evaporated under reduced pressure. Obtained a black colored product. It was purified by silica column chromatography (10:90 ethyl acetate: hexane) to get the compound (3a-d)

The melting point range of o-nitroacetanilide is

Rearrangement and Isomerization Purpose of Rearrangement Experiment The purpose of the experiment is to convert a 1,2-diol (benzopinacol) into ketone (benzopinacolone) by using glacial acetic acid. The name of the rearrangement reaction comes from the rearrangement of pinacol to pinacolone. Reaction Scheme Reaction Mechanism Procedure 0.400g of benzopinacol were mixed with 2ml of glacial acetic acid, and a one tiny crystal of iodine. Then, the mixture was refluxed for around 5 minutes, and then let it cools the benzopinacolone was separated from the solution as a solid.

This slow rate of cooling is essential to preventing the diphenylacetylene from precipitating out of the mixed solvent "too early", when it's temperature was above 59°C, which is the lower bound of the melting point range of diphenylacetylene (59-61°C). The product would thus melt immediately upon recrystallizing and form a separate layer on top of the original solvent in an "oiling out" process. Theoretically this oil could be left to cool until it reached the desired 59°C and crystallized into a solid, but this process would result in crystals that were too small and full of impurities that migrated into the diphenylacetylene out of the solvent. If the recrystallization is adequately cooled past this point, it can be placed in an ice bath to accelerate the remaining recrystallization process and the resulting crystals filtered with a Buchner funnel while washed with deionized

C-alkylation of acetyl acetone (1 equivalent) was done by refluxing it with propargyl bromide (1.1 equivalents) for 12 hours. After completion of reaction the solvent was distilled off and chloroform is added. The suspension was filtered and the solid residue was washed with chloroform three times.

The tables above display the melting point range of each of the chemicals tested. Table 1 represents the results found in part 1 of the lab. It was found that the 50-50 mix has the lowest melting point. This is likely because the less pure a compound is, the lower its melting point will be. The 50-50 mix is the least pure of the 3 compounds so therefore the melting point was lower. In Part two of the lab it was found that the melting point range of the unknown compound (shown in table 2) is closest to the melting point of trans-cinnamic acid. To confirm this, the melting point of the unknown compound was tested next to trans-cinnamic acid and a 50-50 mix of trans-cinnamic acid and the unknown compound. As seen in table 3, while the start point of each of the compounds varied, all three of the compounds had an extremely similar end point.

Recrystallization is a technique to purify organic compounds. Both the impurities and the compound are dissolved. The impurities are forced out, and the purified compound is recrystallized. The purpose of this lab is to use the recrystallization method to purify an impure naphthalene compound using methanol.

The goal of the recrystallization laboratory is to purify chemicals by dissolving their impurities. Both acetanilide and benzoic acid will be utilized as our impure solids. By adding small quantities of solvents such as ethanol and water, we will be able to isolate the impurities and extract them from the solution. What is left will be a solution pure enough to form solid precipitates (crystals). The crystals will be isolated using a Buchner funnel and vacuum filtration.

A. Therefore confirming the unknown used for recrystallization in part A and B is Salicylic acid. The crystals collected from part A had a 26.38% recovery, and the crystals collected from part B had a 27.20% recovery. This shows that macroscale is more efficient, and is a better technique for purifying the compound, since the % recovery is

If a substance is pure, the melting points would be similar; however, for the 50-50 mixture, the melting point was depressed due to the amount of impurity between the two substances. In part two of the experiment, in order to determine the identity of the unknown substance, the compound was heated rapidly at a rate ramp of 10C in order to find the approximate melting point. The substances were similar in ranges as the unknown held a value of 3.8 while acetanilide had a value of 3.7. By using the melting point 115.2C-119.0C, it was determined that the unknown substance was most likely acetanilide. After testing the unknown mixture with acetanilide, it was confirmed that the unknown chemical was in fact

The centrifuge was cool for 15 minutes then place in an ice bath for 10 minutes. After, the centrifuge tube was centrifuged for about two minutes. All the liquid was removed once the centrifuged was done. Only maintaining the solids at the bottom. This centrifuge tube was then dried by a gentle flow of nitrogen until dry and then cooled and massed. The final mass of the centrifuge was 20.3553g. To find the second recrystallization yield, similar steps to the first recrystallization yield were taken. To find the final mass of the yellow solution, the initial centrifuge (20.3809g) was subtracted by the final centrifuged mass (20.355g) to obtain a final mass of 0.025g for the yellow straws. Therefore, 0.0209/0.0507 times 100 gave a 51% yield. This second yield was less than the first recrystallization could have been due to a possible imbalance final weight of the centrifuge tube. Lastly, a melting point of the second recrystallization was taken. The expected literature value 108 Celsius but the compound only reached 96.6 Celsius. This means that there were still some few impurities in the

When cooling the acetanilide solution pure acetanilide crystals are formed. During the vacuum filtration, the acetanilide crystals that were caught in the funnel are washed by ice cold deionized water. Recrystallization is used as a purification method because impurities would not solidify with the crystal and can be easily washed away in the vacuum filtration once the crystal is

The purpose of the reflux ring was to speed up the chemical reactions without having it evaporate or explode. The apparatus was able to include the reactions and maintain a constant volume. The process of distillation was primarily used to separate the liquids after they were heated in a flask. After distillation was done, the remaining distillate was collected and the process of separation, which is a major step of this experiment, was used once all the distillate was collected and separated into layers. The process of separation is used for isolation and identification purposes.

An acetanilide/water mixture is considered a solution when the acetanilide is completely dissolved in water above the melting point of the acetanilide. An acetanilide/water solution is a heterogeneous mixture when it is below the melting point of the acetanilide,

The synthesized product was purified by further recrystallization process. The recrystallized salt was slowly added to the mixed solvent of benzene + acetone (1:2) ratio. The resultant solution was a pale orange colored. The solution was