Sodium hydroxide was mixed with distilled water then was used to react with sufficient ethanol as the first step. In order to make sure the water in air can be eliminated, a small amount of calcium chloride has been placed with the drying tube on the top the condenser. Substituted derivatives of triphenylmethanol are intermediates in the production of the commercially useful. Avoid the diethyl ether from any heat source since it is extremely flammable. Write equations showing how this might be done and how the benzoic acid would be regenerated. Typical of , resonance offers no stabilization of the conjugate base due to being bonded to a saturated carbon atom. These are show below, respectively.
In Experiment 3, the benzoic acid could have been extracted from the ether layer using sodium bicarbonate solution. The water molecule will destroy the nucleophilic property of Grignard reagent. The calcium chloride acts as a drying agent which to absorb all the water from the air in the reflux apparatus and it prevent the atmospheric moisture. Magnesium turning thin shaving with high surface area is usually used in preparation of Grignard reagent due to its large surface area that can increase the reaction rate. The nucleophilic addition of Grignard reagent to methyl benzoate caused the methoxide became the leaving group from the intermediate and the formation of benzophenone.
The formation of Grignard reagent is highly exothermic which will produce a lot of heat energy from the system. One of the reasons is the vapors of the highly volatile diethyl ether helps to prevent the oxygen in the atmosphere to reach the reaction solution. The reaction of phenyl magnesium bromide and benzophenone…. Grignard reagents are reactive enough to also attach esters; however, two equivalents of the Grignard reagent are usually added because less then two equivalents leave a large quantity of unreactive ester. The methyl benzoate ester acts as the carbonyl containing compound in the experiment.
As a result, the nucleophilic addition and base-catalyzed dehydration lead to the formation of the desired product which is dibenzalacetone. Specific precautions, such as completely drying equipment and tightly sealing vials quickly were taken to ensure that the Grignard reaction was free of water. The triphenylmethanol was purified by recrystallization. When the reaction has been initiated, the appearance of bubbles on the solvent surface indicated that the formation of phenylmagnesium bromide start to occurr. Continue refluxing during the 2-minute period. A second alternative is place the flask containing reaction mixture over a sonicator to start the Grignard reaction.
Once the reaction was completed, the solution was heated to reflux for 10 minutes to complete the reaction. The iodine crystal was added into the magnesium surface because the heats from water bath or palm were not enough to initiate the reaction. . The mixture was then recrystallized from methanol and was allowed… 1978 Words 8 Pages Grignard Synthesis of Triphenylmethanol from Benzophenone Purpose: The purpose of this experiment was to synthesize the tertiary alcohol triphenylmethanol from a Grignard reagent, phenyl magnesium bromide. The solution was allowed to reflux for 10 minutes.
The protonation of the aldol took place followed by the hydroxide groups have been eliminated as leaving groups. After 15 minutes of occasional swirling, the products was filtered on a Buchner funnel. Step 9 : Get a vial and cap, weigh the vial with the cap on it, and record the weight. This deviation may be due to the product is not completely dry so that it affects the melting point of the product. Once the reaction has been initiated, the system will reflux itself in the bottom flask without any external heat source.
The double mixed-aldol condensation reaction between acetone and benzaldehyde was carried out. The benzalacetone once formed, can then easily to react with another mole of benzaldehyde to give the desired product in this experiment, dibenzalacetone. The syringe used to add diethyl ether to the reaction will be used throughout the experiment. The mixture is stirred with a magnetic stirrer. Step 7 : Add 1 mL of a saturated NaCl solution to the 5 mL conical vial containing the diethyl ether organic layer as a final rinse.
The elimination process is particularly fast in this case because the alkene is stabilized by conjugation to not only the carbonyl but also the benzene. To carry out a mixed aldol condensation reaction 2. Combine these rinses with the initial rinse within the 50 mL Erlenmyer flask. The mixture of ether and bromobenzene was added slowly to make sure that the Grignard reagent form steadily in the reaction. Step 15 : Clean all glassware and the experimental area. Combine this rinse with the other rinses in the 50 mL Erlenmyer flask.