Alkyl Halide Lab

A cold, wet pipe cleaner was then added to the top of the reaction flask to keep the column cold which caused no vapors to rise into the column.

Day 1. Michael was coming home for vacation from college. When he got home he found out that

In this experiment, an alkyne—diphenylacetylene—was prepared by a double dehydrobromination. Potassium hydroxide (KOH) and high heat were used to accomplish this. The precipitate of this reaction was collected by vacuum filtration. It was then washed with water and recrystallized using ethanol. The product was then isolated again before the weight was taken for further analysis of percent yield. The melting point was also taken to identify that it was the desired product.

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

It was made basic by adding 6 mL of 6M NaOH to the separatory funnel. The pH was taken to confirm that it was basic. Next, 10 mL of dichloromethane was added to the flask. The flask was shaken and the bottom layer was drained in a flask. This was repeated two more times. Na2SO4 was added to the flask to remove water. A flask was pre-weighed and gravity filtration was conducted. After, a TLC was conducted for p-toluidine and there was only one spot on the plate with an Rf of 0.32. Then a boiling stick was added to the flask and was placed on sand bath to completely boil. The weight of the flask was taken again.

ii. The second part of the titration series involves titration of NaOH with Hydrochloric acid (HCL). Again, three reps of titration and a blank titration have to be completed. A volumetric pipet is used to measure 10.00mL of HCL into three labeled conical flasks. Then the flasks are filled with deionized water until about the 50mL mark. A buret is

The pipette was used to transfer 8 mL of the 0.5 molarity solution into the graduated cylinder. Distilled water was added to raise the bottom of the meniscus to the 20.0 mL line and the solution was transferred into the beaker after it was rinsed with the solution. The pipette was used to take a small quantity of the solution and rinse and then fill a test tube with the solution. The amount of 0.2 molarity solution needed to create 20.0 mL of 0.1 molarity solution was calculated as 10.0 mL. The pipette was used to transfer 10.0 mL of 0.2 molarity solution into the graduated cylinder and distilled water added until the bottom of the meniscus reached the 20.0 mL line. The solution was transferred to the rinsed beaker and then a portion placed into a test tube that had been rinsed with the solution. The amount of 0.1 molarity solution required to create 20.0 mL of 0.05 molarity solution was calculated to be 10.0 mL. The pipette was used to transfer 10.0 mL of 0.2 molarity solution into the graduated cylinder and distilled water added until the bottom of the meniscus reached the 20.0 mL line. The solution was then placed into a beaker that had been rinsed with the solution and then into a rinsed test

As the acid was being added, the mixture was being stirred over a stir plate. Once completed, the reaction mixture was poured from the round bottom flask into a 500 mL separatory funnel and its top (organic) layer was extracted into another beaker. The bottom (aqueous) layer was placed back into the funnel and extracted twice with 50.0 mL of ethyl ether each. The newly extracted layers were combined and dried over magnesium sulfate (MgSO4). The dried solution was the decanted into a beaker to remove the MgSO4 salts and the product solution was collected via Buchner vacuum filtration. The resulting product was transferred into an Erlenmeyer flask with an inverted beaker on top and stored in a drawer.

The purpose of this step was to further purify the ester and remove any impurities that may have still remained after the purification in the previous steps. The organic ester layer was then added to a small quick fit flask wherein crushed anhydrous calcium chloride was added. Anhydrous calcium chloride is a drying agent that removes polar compounds by fusing with them. As water is polar and the ester, butyl-ethanote, is not very polar, the anhydrous calcium chloride fused only with any traces of water that may have still been present in the mixture, absorbing them, and therefore, removing them from the ester. To check whether all, or a majority of the water particles had been absorbed, the flask was swirled to see if the anhydrous calcium chloride was clumping anywhere in mixture. If clumping occurred, it meant that it was still fusing with and absorbing water particles and that they had not yet been removed. Once the calcium chloride powder began to flow freely, it was an indicator that most of the water particles had been absorbed. However, to ensure that the ester would be as pure as possible, the anhydrous calcium chloride was left to fuse and absorb the water overnight so that as many water particles could be removed as

While the reflux heating of procedure A was completing, procedure B allowed for the addition of the t-pentyl alcohol of 2-methyl-2-butanol to the solvent-nucleophile solution in a separatory funnel. After the two were shaken and mixed, the separatory funnel was allowed to sit, which let the solution develop the alkyl halide layer. This separation process involving the separatory funnel shaking was important as it allowed the mixture to develop distinct two layers and made for a simple extractionD. The lower, less dense aqueous layer that contained the sulfuric acid and water was drained off and the less dense alkyl halide upper layer was transferred into a beaker that contained solid sodium bicarbonateF. The solid sodium bicarbonate added during

A 25 ml RB flask was set-up up for reflux with a drying tube and 1 ml of 1.5 M of potassium tert-butoxide was added along with 8 drops of 1-bromopentane. This was then heated to 80 °C - 90 °C for an hour. When the mixture cooled, 10 ml of methyl-t-butyl ether was added to the flask. This was extracted and

A 10 mL round-bottom flask was weighed both before and after approximately 1.5 mL of the given alcohol, 4-methyl-2-pentanol, was added. 3 mL of glacial acetic acid, one boiling chip, and 2-3 drops of concentrated sulfuric acid were added to the flask in that order. The reflux apparatus was assembled, the

Experiment 7 introduces the concept of “dehydrohalogenation”. The idea is that alkyl halides may undergo elimination reactions which involve Brønsted–Lowry bases. In this event, a halide anion and a proton are lost to form a new π bond. There are two common types of elimination reactions: either unimolecular (E¬1) (the rate determing step) or bimolecular (E2). E1 elimination reaction is a two step mechanism which requires the formation of a carbonium ion intermediate by the splitting of the leaving group (the halide in this case). After this formation, a loss of a proton (H+) causes a π bond to form. We want the the carbonium ion to be as stable as possible. This ensures that it forms easily as well as increases the rate of the E1 reaction. On the other hand, E2 elimination reactions are a one step mechanism in which a simultaneous removal of a proton by the base leads to the loss of the leaving group, thus generating a new π bond. In this part of the experiment,

In this experiment, dehydration is carried out using cyclohexanol to obtain cyclohexene. This acid-catalysed reaction involves E1 elimination mechanism. The dehydration of alcohol will remove OH- from cyclohexanol to form cyclohexene. Cyclohexene contains a single double bond in the molecule. It is a six carbon aromatic hydrocarbon. Phosphoric acid is mixed with cyclohexanol in the round-bottomed flask and is heated. The phosphoric acid act as a catalyst that increases the rate of reaction but it does not change the overall stoichiometry. The acid catalyst will convert the hydroxyl group into a good leaving group. It is an equilibrium reaction in which the equilibrium is forced to the right (alkene). (Department of Chemistry 2014) Boling chips are added to the distillating flask. If not, the liquid may over boil and shoot out of the

In experiment A, Water soluble alcohols are always tested by using the Lucas reagent to differentiate among the primary, secondary, and tertiary alcohols. Alcohols are soluble in Lucas reagent while their halides are insoluble. Alcohols react with Lucas reagent to form an insoluble alkyl halide. This test depends on the appearance of an alkyl chloride as an insoluble second layer.The formation of alkyl chloride is indicated by the appearance of turbidity in the reaction mixture.The reaction that occurs in the Lucas test is an SN1 nucleophilic substitution which depends on carbocation stability. Only alcohols that can generate stable carbocation intermediates will undergo the reaction. As the reactivity of alcohols with halogen acids is in the order tertiary > secondary > primary, the time required for the appearance of turbidity will be different for primary, secondary and tertiary alcohols which helps to distinguish them from one to another.The tertiary alcohol which is tert-butyl alcohol reacts with Lucas reagent almost immediately to form an alkyl chloride which is insoluble in the aqueous solution.