Experiment 15 & 16: Preparation of 1-bromobutane, an SN2 reaction Preparation of 2-chloro-2-methylbutane, an SN1 reaction Introduction The purpose of this experiment is to synthesize 1-bromobutane from 1-butanol and sodium bromide. In order for this reaction to reach completion there are four major operations that need to be performed. The four major operations include refluxing, simple distillation, separation, and drying. To begin, in order for the compounds to react they will be dissolved in water and sulfuric acid will be added. The addition of sulfuric acid will then generate hydrobromic acid, an important product in the reaction mixture. The hydrobromic acid will react with the 1-butanol when heat is added to the flask …show more content…
At this point the flask was attached to a refluxing apparatus. This process of refluxing helps to purify the mixture and keep the reaction at a constant temperature. Also, before the reaction mixture began to boil the separation of a clear top layer and a cloudy bottom layer helped to indicate that the reaction was working properly. The top layer was the alkyl bromide since the other components of the aqueous layer have the greater density. After the 45 minute refluxing process was complete, the apparatus was set up for simple distillation apparatus distillation commenced. Distillation took place until no more drops of product were dripping from the distillation head. The first drop of distillate occurred when the thermometer read 75°C, the actual temperature was probably a bit higher since the vapors might not have fully reached the bulb of the thermometer. The final drop of distillate was collected at about 115°C. Once the distillate was collected, it was placed in a seperatory funnel and the reaction flask was rinsed with 10 mL of water and added to the seperatory funnel. Rinsing the funnel ensured that all of the distillate from the distillation process was removed from the reaction flask and no product was left on the walls of the flask. After the water was added, two layers formed in the funnel. The top layer was the water and the bottom layer was the 1-bromobutane since the density of 1-bromobutane is higher than that of water.
A small beaker was placed under the arm of the distillation head to catch the distillate. Foil was wrapped around the neck of the round-bottomed flask and a wet paper towel was wrapped around the arm of the distillation head to create a condenser. The flask was heated gently so that the distillate dropped at a rate of two drops per minute. The temperature was recorded as every drop was collected. The distillation began at around 55.0 ℃. The distillation was stopped after 29 drops were collected to prevent the solution from being distilled to dryness. See attached data. The known boiling point of 1-butanol is 117.5 ℃ (Lemonds). The known boiling point of 1-propanol is 97 ℃ (Thiyagarajan). The known boiling point of acetone is 56 ℃ (Forss). The known boiling point of 2-butanone is 79.6 ℃ (Jiang). For unknown #3 the boiling point of the first substance seemed to be around 56 ℃ and the boiling point of the second substance seemed to be around 111 ℃. Therefore unknown #3 seemed to be a mixture of acetone and 1-butanol.
Simple distillation is a separation technique which can be used to separate and purify distillates from a liquid mixture which ideally contains one volatile and one non-volatile compound. If such ideal conditions are not possible—as is usually the case—then simple distillation can be applied as long as the liquid in question is composed of compounds that differ in volatility such that their boiling points differ by at least 40 to 50 degrees Celsius. Because
When the reaction time is up, allow the reaction mixture to cool to about room temperature. Turn off the cooling water and remove the reflux condenser. Transfer the reaction mixture to a separatory funnel. Leaving the boiling chips behind, and washes the mixture with 50 mL of water. Drain the aqueous layer, and leave the organic layer in the separatory funnel. Then carefully wash the organic layer with two successive portion of 5% aqueous sodium bicarbonate, draining the aqueous layer after each washing. During the first washing, stir the layers until gas evolution subsides before you stopper the separatory funnel, and vent it frequently thereafter. Dry the crude isopentyl acetate with anhydrous magnesium sulfate or sodium sulfate, and filter I by gravity. Using standard-taper glassware, assemble an apparatus for standard scale simple distillation. Be sure the thermometer is straight up as shown in the picture below. Distill the crude product, collecting any liquid that distills between 137oC and 143oC. Record the actual boiling range. Wait until the entire thermometer bulb is moist with condensing vapors, liquid is distilling into the receiver, and the temperature is stable. Stop the distillation when only a drop or so of liquid remains in the pot or when the temperature reaches 143%. Using a Carbowax column or another suitable
A distillation apparatus was then set up. This distillation apparatus was used to help separate the ester, to hopefully obtain a pure ester as a distillate. The ester was distilled by heating the pear-shaped with a Bunsen burner. However, before beginning the boiling of the ester, a mercury thermometer was placed in the fractioning column. The bulb of the thermometer was levelled with the intake to the condenser so that it was ensured that the temperature recorded was that of the ester vapour that was condensed in the condenser and not the fractioning column. This was important as the temperature of the vapour that was being condensed in the condenser represented the boiling point of the ester, which had to be recorded to obtain a distillation range. Using a 10mL measuring cylinder, the volume of the collected ester distillate was measured and recorded to determine the yield. The clarity, appearance, and odour of the ester were then noted to help determine how pure the ester distillate
8.5 mL of acetic acid and 5.0 g (6.2 mL) of isopently alcohol were measured out and added into a 50-mL round bottomed flask. A few boiling stones were added to the flask and then 1.2 mL of concentrated sulfuric acid was added to the mixture under the fume hood. The reflux apparatus was set up- a condenser mounted vertically onto the reaction flask and two hoses attached to it. The water was to flow into the condenser through the bottom inlet and out throught the top outlet. A heating mantle was placed under the reaction flusk and the mixture was let to heat to boiling and reflux for sixty minutes. After the reflux period, the reaction flask was let to cool down and its contents were then transferred to a separatory funnel. 10 mL of water was added to the mixture, funnel was closed with a stopper and carefully shook while venting to wash out the mixture. The equous (lower) layer was drained off,
A filter paper was added to the Büchner funnel. The faucet, which acted as a vacuum source, was turned on. Before pouring the reaction mixture into the filter, the filter paper was wetted using distilled water. A pair of tongs were used to transfer the reaction into the filter from the beaker. After most of the reaction was in the filter, the beaker was rinsed twice with 5mL of distilled water each time. The contents of the rinse in the beaker were emptied into the filter. After the filtration was complete and the dark residue of the aluminum can pieces was separated from the clear reaction mixture, the filtrate was transferred into another clean 250mL beaker. Then the filter flask was rinsed with 10mL of distilled water and added to the filtrate in the new reaction beaker.
Using simple distillation would have yielded little or no desired product. The distilled products from the reflux solution were found to be close to the appropriate temperature ranges for the products. When placed in the separating funnel, the organic product layer was on the bottom. This showed that it was denser than water, and helped determine that the correct products were yielded and produced during this reaction as well as separated correctly. The percent yield of the products of these reactions was low; 1-bromopropane was 2.279% and 2-bromopentane and 3-bromopentane was 35.77%. There are several errors that probably affected these yields. One possible error was that the reflux condenser was not tightly secured to the connections of the flask being heated and the collecting flask, which may have resulted in loss of the volatile reagents and products. Also, premature removal of the reflux condenser and inadequate cooling of the condenser can also result in loss of distillate and volatile vapors, by not allowing all of the distillate to travel the condenser to the collection flask. Due to the volatility of the reagents being used and the products formed, if each connection in the apparatus is not greased and connected properly it can also result in a loss of product through evaporation. Separation may also cause loss of products when draining the layer of product
To begin the reaction, 1.008g of Maleic anhydride was added to a 25ml Erlenmeyer flask. Next, roughly 4.0mL of Ethyl acetate was added to flask. The flask containing Maleic anhydride and Ethyl acetate was shaken to dissolve solid. Then, 4.0mL of Petroleum ether was poured into the into the same flask. Finally, 1.0mL of Cyclopentadiene was carefully added to the other substances. Following the addition of Cyclopentadiene produced an immediate but short-lived boiling, along with the release of heat for a brief period. A white solid began to form, signaling that recrystallization was underway, and the flask was left to cool to room temperature to continue this process. A Cloudy white liquid with sediment appeared to form after about 15 minutes.
Prior to beginning the procedure, a distillation setup was constructed in order to prepare for a later step in the procedure; a diagram of the construction was included in Figure 1.A. In a clean 50-mL Erlenmeyer flask, 5 mL of water were placed, and, with extreme caution, 4.0 mL (8.0 g, 0.08 mol) of concentrated sulfuric acid were added to the flask while swirling; it was emphasized that this acid can be highly corrosive and should be handled with care, especially while pouring it into the water1. It was observed that the flask began to heat up as the acid was added, and began to release a gas for a brief moment. Afterwards, the diluted acid was allowed to cool to about room temperature and 3.2 mL (3.0 g, 0.030 mol) of cyclohexanol were added to the mixture. The contents of the flask were carefully transferred to a 25 mL round-bottom flask that was attached to the distillation setup. The contents were distilled at a steady pace, making sure that all the junctions and flasks were clasped appropriately in order to avoid any accidents. The distillation was allowed to continue until the liquid found in the starting flask turned black and began to emit a white gas. It was noted that at around 53 °C distillate began to form, and at around 92 °C the liquid turned black. Approximately 2.8 mL of distillate
reaction mixture was refluxed for 1 hour and the flask was cooled in a beaker in the
Pronin, Reiher, and Shenvi provide a shortcut to produce compounds with tertiary alkylisonitriles or tertiary alkylamines from tertiary alcohols through a transformation similar to a Sn2 reaction. This could make it easier to synthesize natural products that have anticancer, antimalarial, or antifungal properties. In a Sn2 reaction, a nucleophile displaces a leaving group so that the substrate’s stereochemistry is flipped. The structural flip could change a compound’s chemical properties.
In conclusion, out of the reactions for NaI in acetone, 1-bromobutane reacted the fastest, and did not require
This experiment consisted of a simple distillation of a hexane and heptane mixture. The first, third, and fourth fraction were taken and recorded in Table-1. The first fraction temperature ranged from 29.7°C – 38.2°C. The second fraction temperature range was recorded as 40.3°C-41.7°C, but this fraction was not used. The third fraction temperature range was determined to be 41.8°C – 36.5°C. Finally, the fourth fraction temperature range was 34.5°C-27.3°C. The ranges of the temps following the second fraction began to decrease, causing a discrepancy in the data. This decrease in data can be linked to the formation of water or condensation on the tip of thermocouple. The first, third, and fourth fractions were collected and further analyzed using
Many mechanistic reactions are utilized and are interrelated in order to produce the desired product in an organic synthesis. These mechanisms may be generally categorized2 into the following classes: addition, elimination, substitution, and rearrangement. Of these, substitution reactions are of particular significance in halogenation reactions of alcohol-containing compounds, in which the alcohol functional group is replaced by a halide ion (i.e. Cl- or Br-). Alcohols are the most common precursors to alkyl halides and signify a very substantial reaction in organic synthesis4. Substitution reactions can occur via two mechanisms2, namely unimolecular nucleophilic substitution (SN1, a stepwise process) and bimolecular nucleophilic substitution (SN2, a
One other process intensification method that is relevant to this study is the reactive distillation and will be discussed in the following section.