Lab 5 n-Butyl Bromide Preparation
Introduction:
The purpose of this lab is to properly extract and distill n-butyl bromide It is ideal to perform this technique with accuracy, which can be measured by the percent yield.
Chemicals:
n-Butyl Bromide- clear, yellow liquid that is slightly soluble in water. Molar weight of 137.02g and has zero reactivity.
Sodium Bromide- white, crystals, granules. Soluble in water with no reactivity. Molar weight of 102.89g.
Sulfuric Acid- colorless liquid that is miscible in water and produces heat. Highly reactive and has molar weight of 98.08g.
Sodium Bicarbonate- baking soda, white lumps that are soluble in water. Zero reactivity and has molar weight of 84.01g.
Water- polar with
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I then added 2.4mL of water and about 2.436g of sodium bromide to the flask and put it in an ice bath. I slowly added sulfuric acid drop by drop to the solution. Then I removed the flask from the ice bath and placed it in the assembled reflux apparatus and began the heating process for 60 min. After the heating process was complete, I observed that the organic layer of the mixture turned bright red. I extracted the organic layer by removing and discarding the aqueous bottom layer using a pipet. To make sure I had no organic solution in the aqueous extract, I added a drop of water and it dissolved proving that my aqueous extract was just aqueous. I put the remaining solution in a clean 5mL vial and put it in the freezer.
Day 2:
After freezing the solution overnight, the organic layer turned a copper/brown color. I added 2mL of H2SO4 to the vial and the two layers formed with the organic layer on top. I removed and discarded the aqueous solution using a pipet. I then added 2mL of H2O and two layers formed with the organic layer on the bottom. Using a pipet I transferred the bottom layer to a clean 5mL vial. I then added 2mL of sodium bicarbonate a little at a time, shaking and venting frequently. After the layers separated I transferred the lower alkyl halide layer to a dry 3mL vial and dried this solution with granular anhydrous sodium sulfate. I did not have enough alkyl
In this Chemistry Lab the main objective is to perform accurate chemical analysis for the quantity of elements and compounds in a sample. There will be a compound made then synthesized. The methods used were acid-base titrations, redox titrations, gravity filtration, and distillation. General conclusions included
Suppose a household product label says it contains NaHCO3. How would you test this material for the presence of sodium bicarbonate?
Experiment 55 consists of devising a separation and purification scheme for a three component mixture. The overall objective is to isolate in pure form two of the three compounds. This was done using extraction, solubility, crystallization and vacuum filtration. The experiment was carried out two times, both of which were successful.
14 mL of 9 M H2SO4 was added to the separatory funnel and the mixture was shaken. The layers were given a small amount of time to separate. The remaining n-butyl alcohol was extracted by the H2SO4 solution therefore, there was only one organic top layer. The lower aqueous layer was drained and discarded. 14 mL of H2O was added to the separatory funnel. A stopper was placed on the separatory funnel and it was shaken while being vented occasionally. The layers separated and the lower layer which contained the n-butyl bromide was drained into a smaller beaker. The aqueous layer was then discarded after ensuring that the correct layer had been saved by completing the "water drop test" (adding a drop of water to the drained liquid and if the water dissolves, it confirms that it is an aqueous layer). The alkyl halide was then returned to the separatory funnel. 14 mL of saturated aqeous sodium bicarbonate was added a little at a time while the separatory funnel was being swirled. A stopper was placed on the funnel and it was shaken for 1 minute while being vented frequently to relieve any pressure that was being produced. The lower alkyl halide layer was drained into a dry Erlenmeyer flask and 1.0 g of anhydrous calcium chloride was added to dry the solution. A stopper was placed on the Erlenmeyer flask and the contents were swirled until the liquid was clear. For the distillation
1 litmus paper, red - in bag 2"x 3", Copper (II) Carbonate in Vial, 1/2 Full
3.0g of salicylic acid was weighed then 3.0mL of acetic anhydride and 6 drops of 85% H3PO4 were added to it. The mixture was warmed over a water bath for 5 minutes while stirring. After warming, 20 drops of distilled water was slowly added. 15mL of water was added then the solution was heated until it became clear. It was allowed to cool and was placed in an ice bath until the solution becomes cloudy. Using pre-weighed filter paper, the mixture was filtered and was allowed to dry in the filter paper.
Sodium bicarbonate has a molar mass of 84.0 g/mol. It has a melting point of 50°C and can be an irritant.
After adding all four reactants and keeping the mixture cold a cloudy, white residue was present in the bottom of the flask.
After about 1 minute of shaking, the two layers separated. The organic layer on the top layer (consisted of ethyl acetate and naphthalene) collected for further experiment; by adding Sodium Sulfate into organic phase and filtering the Na2So4 from the solution using the wool. The dried organic layer was weighed to get its mass and the residue of Na2SO4 were rinsed with ethyl acetate under vacuum (rotary evaporator). The acid extract on the bottom layer which is a combination of benzoic acid and NaOH were collected in the 50 mL Erlenmeyer beaker for the recovery of acid.
Wash (swirl and shake) the organic layer with one 10-mL portion of water and again drain the lower aqueous layer. Transfer the organic layer to a small, dry Erlenmeyer flask by pouring it from the top of the separatory funnel. Dry the crude t-pentyl chloride over 1.01 g of anhydrous calcium chloride until it is clear (see Technique 12, Section 12.9). Swirl the alkyl halide with the drying agent to aid the drying.
After putting the CH2Cl2 to a beaker containing the drying agent anhydrous sodium sulfate, a sticky white solid was recovered.
Aim: To classify unknown substances according to their structure type and to observe how the structure of materials affects their uses.
1.) Transfer the distillate to separatory funnel. Fluid didn’t seem very clear but sufficient to finish our lab on time.
After the mixture finished refluxing, the flask was then cooled on ice. A sulfuric acid solution was then prepared by pouring 4.5 mL of concentrated H2SO4 over 50 grams of ice and then diluted to 75 mL by adding enough tap water to reach 75 mL. The sulfuric acid solution was then cooled on ice.
The boiling point was 129 oC which was lower than the literature boiling point, 142 oC. Analysis by infrared spectroscopy showed the impurity (most likely CH2Cl2) containing a carbon-chlorine bond.