Bromination of Trans- Stilbene to Form 1,2- Dibromo- 1,2-Diphenylethane

Discussion: In the synthesis of 1-bromobutane alcohol is a poor leaving group; this problem is fixed by converting the OH group into H2O, which is a better leaving group. Depending on the structure of the alcohol it may undergo SN1 or SN2. Primary alky halides undergo SN2 reactions. 1- bromobutane is a primary alkyl halide, and may be synthesized by the acid-mediated reaction of a 1-butonaol with a bromide ion as a nucleophile. The proposed mechanism involves the initial formation of HBr in situ, the protonation of the alcohol by HBr, and the nucleophilic displacement by Br- to give the 1-bromobutane. In the reaction once the salts are dissolved and the mixture is gently heated with a reflux a noticeable reaction occurs with the development of two layers. When the distillation was clear the head temperature was around 115oC because the increased boiling point is caused by co-distillation of sulfuric acid and hydrobromic acid with water. When transferring allof the crude 1-bromobutane without the drying agent,

The vial was removed from the heat and cooled to room temperature. The spin vane was rinsed with 2-3 drops of warm water over the conical vial. The vial was cooled to room temperature then placed in an ice bath for 15 minutes. The liquid was decanted from the mixture and the resulting crystals were dried on filter paper. The crystals were then placed on a watch glass for further drying. The crystals were weighed and a small sample was placed into a capillary tube for melting point determination.

21) After all of the solid dissolves, move the flask from the hot plate and allow it cool to room temperature. After a while, crystals should appear in the flask.

The product was then suspended in 2 ml of water with a stir rod in a 50 ml Erlenmeyer flask and heated to boiling. Water was added in one milliliter increments until all the product was dissolved (18 ml added total). The saturated solution was allowed to slowly cool, and gradual white crystal formation was observed. Recrystallized product was collected once more by suction filtration with the Hirsch funnel once crystallization ceased. Collected product dried on a watch glass for a week, weighed 0.14 g (1.2 mmol), and the melting point was 139°-141°

mL cylinder to the beaker on the stir plate and empty it into the beaker. Place the pH probe in the beaker and record the pH in the data table. Drag the beaker to the red disposal bucket. Double-click the bottle of NaHCO3 to move it to the Stockroom counter. Repeat steps 5 and 6 for KNO3.

The first experiment begun by filling a 600-ml beaker, almost to the top, with water. Next, a 10-ml graduated cylinder was filled to the top with water. Once water was added to the beaker and graduated cylinder, a thumb was placed over the top of the graduated cylinder. This would ensure that no water was let out and no bubbles were let into the graduated cylinder. Next, it was turned upside down and fully submerged into the beaker. Then, a U-shaped glass tube was attained. The short end of the glass tube was placed into the beaker with the tip inside of the graduated cylinder. Next, a 50-ml Erlenmeyer flask was received. After, 10-ml of substrate concentration and 10-ml of catalase/buffer solution were placed into the flask. A rubber stopper was then placed on the opening of the flask. After adding these, the flask was held at the neck and spun softly

Reaction 1 involved a primary alcohol (OH), weak leaving group in the starting material and a reaction with a strong nucleophile (sodium bromide) and a polar protic solvent (sulfuric acid). The reaction was carried out through reflux and the product had a relatively high yield (75%) (Scheme 1).

Tube 4 now should only have crude solid in the tube and it is then weighed. The tube is placed into a 50℃ water bath and then approximately 0.5 -1 ml of methanol is added, as well as H2O until the solution gets cloudy, once the solution is dissolved it is cooled to room temperature and then iced. The crystals are then collected using a Hirsh funnel. Next a small amount (~ 0.1g) of the crystals are placed into a melting point tube and placed into the melting point machine to record the unknown neutral substances melting point.

The purpose of this experiment is to examine the reactivities of various alkyl halides under both SN2 and SN1 reaction conditions. The alkyl halides will be examined based on the substrate types and solvent the reaction takes place in.

The pipet was put into the top of the condenser and leaving no open spaces. The vacuum served to get rid of the nitrogen oxide gases that were formed during the oxidation reaction. The solution was heated for 30 minutes, beginning the time when the first sign of nitrogen oxide fumes were observed. After the 30 minutes, the solution was removed and cooled for a few minutes. The solution turned was a brownish-yellow color and all the crystal were dissolved, leaving a liquid. The solution was then transferred, using a Pasteur pipet, to 3 mL of water in a beaker. The reaction flask was rinsed to remove the remainder of the solution. The solution was stirred with a glass rod until room temperature of the solution was achieved. A yellow solid was to form, but instead the solution remained aqueous in the case of the specific experiment explained here. With additional scraping of the solution with a glass rod, no crystals formed at all. The next procedure, if the crystals had formed was to crush the solid with the glass rod and filter the solid until the crystals were dry. The mass would then be weighed and the crystals were to be recrystallized with 95% ethanol. The crystals were to be cooled in ice water to get full crystallization and then the crystals were to be filtered and air dried, then weighed.

Determining how a mechanism comes to be is crucial as a scientist and arriving to conclusions is a crucial component which lead to examining and determining which mechanism takes place when two or more substrates are made to react. At the end of the experiment a mechanism was determined based on the purified product’s melting point. This was accomplished by having the reaction take place but also through acquiring the melting point and comparing the number to the melting point which was already established by the scientific community. (Q1) When 0.252 g of trans-cinnamic acid was mixed in 2.5 mL glacial acetic acid and 0.434g pyridinium tribromide was added, the resulting product reflects an addition reaction. In general, reactions take place to achieve its lowest Gibb’s free energy because it’s at

This process was then repeated two more times with subsequent additions of 10 mL of the 0.5M aqueous NaHCO3 and the aqueous layers drained off into the above mention labeled 100-mL beaker. Finally 5 mL of deionized water was placed into the funnel and mixed. The water was then drained off into the beaker containing the aqueous solution extracts. The solution was then saved until need later in the experiment.

First, a bottle was found and its top was cut. The bottle, now without a top, was filled halfway with paper. It was then taken outside. Dirt was dug up from the ground and poured into the bottle until the bottle was 1/2 full. Next, 3-5 of calcium carbonate was added along with 3-5 grams of epsom salt. Next, this solution was mixed and then the bottle that held it was tapped to release any trapped air bubbles. Afterwards, tap water was added until only 1 inch of the bottle was left unfilled. Then saran wrap was placed over the opening with a rubber band to keep said wrap in place. Finally, the column was placed on a table near a window for 6 weeks.

Crystals were collected in a Buchner funnel, washed with alcohol, then ether, then transferred into a sample tube for storage.

Sodium hydrogen carbonate was added to the solution until it becomes neutral. Ph paper was used for this test to determine its ph value.