Wittg Synthesis Of 1,4-Diphenyl-1,3-Butadiene

Purpose of Experiment
The purpose of this experiment was synthesize 1,4-Diphenyl-1,3-butadiene from benzyl triphenylphosphonium chloride and pure trans-cinnamaldehyde using Wittig reaction process to convert the carbonyl group in trans-cinnamaldehyde into a carbon carbon double bond.


Results
The weight of the product from the experiment was 0.156g, and the melting point obtained was 145°C. Therefore, the product was 1,4-Diphenyl-1,3-butadiene, which has a melting point in the range of 151-153°C, because it has a melting point which is closer to that of the unknown.
Below is the percent yield of the product obtained :
Mole of product is 1mmol because of 1:1 mole ratio of 1,4-Diphenyl-1,3-butadiene with trans-cinnamaldehyde
(1mmol )/(206.29g/mol) = 0.206grams of 1,4-Diphenyl-1,3-butadiene
Percentage yield = (0.156g )/0.206g x 100%=75.6%

Discussion
The yield obtained from the experiment was 75.6% of the actual yield. The discrepancy might have been from the design of the experiment. Before and after the aqueous sodium hydroxide was added to the reaction, the reaction was supposed to be mixed thoroughly in order to facilitate the reaction between the compounds added.The discrepancy might have resulted from incomplete reaction between the reaction constituents.
The lower yield of product might have been from the separation of the aqueous and the organic layer after washing the crude product. Pipetting away the product along with the aqueous layer might have resulted from a reduced product of 1,4-Diphenyl-1,3-butadiene.
The melting point obtained from the solution was 145°C , and differed from the actual melting point by 6-8°C. The discrepancy in the result might have been from the equipment used. The solution was inserted into the machine while it was warm (about 60°C). This might have led to the lower boiling point.
The obtained product was 1,4-Diphenyl-1,3-butadiene because the melting point was very similiar to that of the predicted product. The physical features such as color, which was white, melting point, melting point, texture and so on was also similar to that of the predicted product.

Conclusion
The method of characterization used in this experiment supports purity of the product obtained. The product was much like the hypothesized.
The purpose of the experiment was to synthesize 1,4-Diphenyl-1,3-butadiene using the Wittig reaction. The objective and purpose of the experiment was obatined with the method that was implemented to synthesize and purify the product. One way this experiment could be improved is the strictly follow the procedures, and avoid taking the melting point with a system that is not at room temperature.

Nitration of Naphthalene

Purpose of experiment:
The purpose of this experiment was to nitrate naphthalene with nitronium ion, which is formed at low concentration from a reaction of nitric acid and sulfuric acid. Naphthalene is a house product used... The major product from the reaction is the kinetic product, the one that forms the more stable cabocation intermediate.

Method and procedure:
Into a 5-ml conical vial, 1.0ml of mixed 1:1 sulfuric acid and nitric acid was added. 0.50g of finely divided naphthalene was added in small portions to the solution while stirring after each addition, and cooling to keep the temperature around 45-50°C. The reaction mixture was then stirred in a 60°C water bath for 20minutes after the addition of naphthalene.
When the reaction cooled to room temperature, the solution was transferred to a beaker containing 25ml of ice-cold was with stirring. Yellow crystals are allowed to form, and then the liquid content is removed with filter-tip pipet. The solid was then boiled with 10ml of fresh water for 10minutes.
The mixture was cooled in ice and the product was collected by vacuum filteration. 0.1 of the crude product was then recrystallized for 5minutes with 5ml of hexane under reflux. The hot solution was filtered using a preheated filtering paper. Crystallization occurred, and then the product was collect by vacuum filteration. Th product was dried and the melting and mass were measured of the product, nitronaphthalene.
Result:
The total mass of the product obtained was 0.57g, and the melting point of the product was between 45-50°C.
The theoretical yield of the product is as follows:
Moles of naphthalene = mass of naphthalene / molecular weight of naphthalene
Moles of naphthalene = 0.50g x 1mol/128.17g = 0.00390mole of naphthalene
Because nitronaphthalene and naphthalene are in 1:1 mole ration,
Moles of nitronaphthalene = 0.00390mole
Theoretical weight of nitronaphthalene = 0.00390mole x 173.17g/mol (molecular weight of nitronaphthalene) = 0.676grams
Perencent yield = 0.57/0.676 x 100% = 84.3%

Discussion:
The result obtained from the experiment was 84.3% yield of the product, and the melting point ranged from 45-50°C. The melting point of the possible results are 61°C for 1-nitronaphthalene, and 79°C for 2-nitronaphthalene.
Even though there is discrepancy in the result obtained from the experiment, the product is more likely to be 1-nitonaphthalene because its melting point is closer to that of the product obtained. They also exhibit the same physical and chemical properties.
The discrepancy in the result obtained may have been from various sources during the experiment. During vacuum filtering, if not properly performed, some of the product might have been lost, therefore decreasing the amount of the product obtained. Another source might have been from the addition of naphthalene to the m1:1 mixture of nitric acid and sulfuric acid. The reaction probably did not fully react if the naphthalene was added at once without stirring. Again, this might have caused the discrepancy in result.
Conclusion:
The purpose of the experiment, which was to synthesize nitronaphthalene, was accomplished through the method implemente in this experiment because of the similarity between the obtained product and the predicted outcome.
This experiment can be improved by circumspectly following the procedure, carefully adding the finely divided naphthalene in little amounts in order to facilitate a good reaction between the nitronium ion and naphthalene.

Synthesis of Triphenylmethanol

Purpose of this experiment:
The purpose of this experiment was to synthesize triphenylmethanol. Triphenylmethanol is a white crystalline aromatic compound, which produces an intensely yellow color in a strong acidic solution due to formation of carbocation. Grignard reaction technique was used in this synthesis.



Method and procedures:
Into a 3-ml conical vial, 3.80mmol of benzophenone was dissolved in 2.0ml of anhydrous ethyl ether . When the reaction cooled, after the ether stops boiling, the septum cap was removed, and a dry stir bar was dropped into the reaction flask and the cap was replaced afterwards. The stirrer was started. A syringe was used to add about three drops of benzophenone solution at a rate sufficient to keep the reaction mixture boiling gently without external heating.
When the addition was complete, 0.5ml anhydrius ether was used to rinse the vial that contained benzophenone solution. A warm water bath was used to heat the reaction mixture for another ten minutes, while stirring with stir bar still in the solution.
The reaction was then allowed to cool to room temperature. A syringe was used to add 1.0ml of water drop by drop to the reaction flask, and the reaction is allowed to subside. While stirring, 2.0ml of 5% (1.4M) hydrochloric acid was added to the reaction. When all the reaction subsides, and all the white solid dissolved, stirring was stopped.
The reaction was transferred to a centrifuge tube using a small amount of solvent-grade ether, leaving the stirr bar and any undissolved magnesium behind. The solution was shaked gently to mix the layers thoroughly. Emulsion might formed in the solution, but a wooden applicator stick was used to break it up.
The aqueous layer was removed and discarded from the solution circumspectly. The remaining solution was washed with 3ml of 5% aqueous soldium bicarbonate, and then with 3ml of saturated aqueous soldium chloride. The ether solution was then dried with anhydrous magnesium sulfate. Then the ether was evaporated and a solid residue was left behind.
To the solid residue, 2.0ml of hexane was added. A flat-bladed microspatula was used to rub and grind the solid in the solvent for 2-3minutes. The product was collected by vacuum filteration. The product, crude phenylmethanol, was then recrystallized from a 2/1 mixture of hexane with absolute ethanol. Triphenylmethanol crystals was allowed to form (slowly) for about 30minutes.It was dried, weighed and it’s melting point was recorded.
Result:
The final weight of product obtained from the reaction was 0.51grams, and the melting point ranged from 132-140°C. The actual melting point of triphenylmethanol is 164°C.
The percent yield of the product obtained is as follows :
(0.00380mol benzophenone)/1 x (1mol triphenylmethanol)/(1mol benzophenone) = 0.00380mol triphenylmethanol
Theroetical yield : moles of triphenylmethanol x molecular weight of triphenylmethanol
0.00380mol x 260.33g/mol = 0.989grams.
Percent yield = (actual yield)/(theoretical yield) x (100 %)/1
Percent yield = (0.51mol triphenylmethanol)/(0.989mol triphenylmethanol) x (100 %)/1 = 51.57%

Discussion:
The yield obtained from the experiment was 0.51g, which was 51.57% of product expected. The melting point was 132-140°C, which differred from the actual melting point by about 30°C . However, the product obtained exhibited the same properties as the expected compound, triphenylmethanol.
There was a lot of discrepancy from the results of the experiment. Sources of the discrepancy was from a few mistakes in the procedures. While vacuum filterating, some of the product were spilled, and as a reult this decreased the final weight.
Since the method implemented in this experiment required the use of dried equipments in order to avoid contamination of reaction, an error might have resulted from improper use of clean dry equipments as expected.
Another source of error might have been from washing and drying the product. While performing this procedure, part of the organic part of the liquid might have been removed and discarded along with the aqueous layer.This also might have caused the inconsistency in results obtained
Conclusion:
Although a few sources of errors caused a reduced yield of product, the purpose of the experiment, which was to synthesize triphenylmethanol, was achieved through the method and procedure used in this experiment. One way this experiment could be improved is to ensure that the reaction is not been contaminated by water or spilled while heating, stirring or vacuum filterating.