• After the flask was heated, I removed it from the heating mantel and allowed it to cool to room temperature. • Next, I poured 15mL of absolute ether and 9mL of bromobenzene into the 250mL flask and waited 5 minutes for any reaction. • There were no signs of reaction after 5 minutes; therefore the lab assistant used a glass stirring rod to crush the magnesium in order to get the reaction started. When this was done, the liquid became cloudy, rapidly bubbling, and the color turned rusty red. • Next, I added 25mL of absolute ether and attached a reflux condenser to the flask.
We then recrystallized our sample using 5 ml of warm acetone that was heated on a hot plate under a hood. The warm acetone was poured in to the beaker with our crude sample and swirled. The beaker with our sample was then placed in to an ice bath to cool and
With increasing temperatures the solute can be dissolved by a solvent during recrystallization. Experimental section Preparation of Chalcone To prepare chalcone 2.1mL of NaOH in was dissolved in 40mL of water and about 25mL of ethanol was added in a 125mL Erlenmeyer flask as soon as pellets were dissolved. Then 0.080 mole of acetophenone was stirred into the 125 mL flask, then place into an ice bath. At once 0.080 moles of bezaldehyde was added to the mixture and stirred all the while temperature was kept between 20-30°C. A stopper was placed on the flask while the mixture was stirring with stirrer for 11/2 hours.
Once dry, 2.2 mL of styrene were added to the round bottom flask, and an ice bath and mechanical stirrer were placed under the reaction vessel. A total of 6.2 ML of 1.0M BH3-THF were added to the reaction vessel slowly by a syringe. This addition took place over a 30 minute time period. The vessel was then left alone for 50 minutes. After which time, 2.1 mL of 30% hydrogen peroxide was added slowly followed by sodium hydroxide until a pH of 8 was observed.
* Pour a little ether over the nutmeg residue on the filter paper so that any Diethyl ethanol traces clinging to it is washed down and mixed with the filtered liquid underneath. * Filter the mixture by gravity filtration, washing the nutmeg residue with 10ml of diethyl ether. Evaporate the Ether from the filtrate * Recrystallize the product from ethanol. Filter using a Buchner funnel and wash them with cold water as shown in the diagram (see figure 2). * Let the crystals dry for one week, record the weight and take a sample and put into a glass capillary tube to obtain a melting point using the Melt-Temp machine.
Rinse the tube with distilled water several times. Add about 1 mL of the solution to be measured. Tilt and turn the cuvette so that the solution has contact with all the surfaces. Discard this solution and repeat this rinse once more. Fill the cuvette about 3/4 full of the solution you wish to test.
The normality of the unknown base is calculated after the solution has reached the end point. The amount of substance being delivered is calculated in units of equivalents per litre using the formula: VaNa = VbNb Experimental In order to titrate the acid with the unknown base, a solution of the acid was prepared. 5.1722 (±10%)g of potassium hydrogen phthalate acid is obtained using a weighing boat and transferred into a volumetric flask containing 250mL of boiled distilled water. Volumetric flask was shaken several times in order to assist the powder to dissolve. Once dissolved, 24.9734 (± 0.0045)mL of acid was pipetted into an Erlenmeyer flask along with 25mL of cool (recently boiled) distilled water.
Then place the water in the 25ml beaker for the heating bath and lower the set-up so that when the 25ml round bottom flask is immersed the beaker is about 2/3 full. 5. When that is finish, using the highest setting on the hot plate heat the water until it is nearly boiling. Then turn the heating bath off. 6.
The pH recorded by using pH electrode before adding NaOH. The solution titrated by 2 ml of NaOH each time and the pH recorded until the color change. These steps were done for the two known solutions and the unknown solution. Part 2 10 ml of vinegar placed in 100ml volumetric flask and deionized water added until the mark. The solution transferred in 150 ml beaker labeled as beaker #1.
Success of this technique was measured by finding the recovered mass of caffeine. Procedure In a 500-mL Erlenmeyer flask, place 30 g of ordinary dry tea, 300 mL of water, and 15 g of powdered calcium carbonate. After boiling the mixture gently for 20 min, occasionally swirling it, add 5 g of Celite or other filter aid, filter the hot mixture in a Buchner funnel, and press the filter cake firmly with a large cork to obtain as much of the liquid as possible. Cool the aqueous extract to 15-20C, transfer it to a separatory funnel, and extract the caffeine with four successive 25-mL portions of dichloromethane. Transfer the extracts to a simple-distillation assembly and distill off all but 10 mLof the solvent on a steam bath.