Grignard Reaction Lab Report

To begin Lab 7 of Chem 115, a clean and dry porcelain crucible and its cover were obtained. Next, an iron ring was attached to a ring stand. A clay triangle was placed on top to the ring and a Bunsen burner was placed under the ring. Following the setup for the experiment, the crucible and its cover were placed on the clay triangle and were heated for about five minutes. After, the burner was turned off and the crucible and cover were left to cool to room temperature. Once the crucible and its cover had reached room temperature, tongs were used to move them to a wire gauze. Using the wire guaze, the crucible and its cover were transported to an analytical scale to weigh and record the mass of it. Next, a strip of magnesium was obtained and

Any amount of H2O present would react with and therefore ruin the Grignard reagent. The negative charge on the Grignard carbon would pop a proton off of water, and the resulting hydroxide would react with MgBr2. Since all of the water and moisture was removed, the reaction should run successfully. For this experiment’s reaction, bromobenzene is turned into phenylmagnesium bromide, a Grignard reagent. Then, the Grignard reagent is reacted with benzophenone to yield a molecule with a negative charge on the oxygen. This molecule is worked up and protonated to yield triphenylmethanol.

Sandpaper was used to remove impurities from the magnesium strips, resulting in a grey strip, with a bit of metallic lustre. The strip of magnesium received was extremely malleable and was easily cut into 1 cm strips and folded into a tiny ball.

However, it can be minimized by having a larger concentration of magnesium than halide. With this, it will cause the halide to react with magnesium instead of other atoms in the solution. When the halide encounters magnesium atoms, the formation of the Grignard reagent occurs. By adding a small amount of halide, dropwise, at a time this lowers the ratio of halide to magnesium. The magnesium concentration decreases while the Grignard reagent increases. The halide at the end of the reaction will mainly react with the Grignard reagent since most of the magnesium will be used in forming the Grignard reagent. Therefore, the side reactions are preferred to occur at the end of the experiment, so the production of them are minimized as much as

This allows for a weak acid to attach to form the unknown carboxylic acid. Sulfuric acid, a dilute acid solution, was added to protonate the solution. To minimize the amount of bubbling that occurred from the exothermic reaction, it was added slowly so that the sulfuric acid reacted with the excess magnesium. Anhydrous diethyl ether, containing no water, was used as the solvent in preparing the Grignard reagent because the oxygen contains a lone pair that can interact with the partial positive on the magnesium which stabilizes the metal complex. Another potential solvent could be THF, tetrahydrofuran, or hexane, but diethyl ether is a better solvent since it contains oxygen.

3. The third source of error is not knowing for how long to exactly heat the magnesium until it no longer ignites and forms into a white powder of magnesium oxide. In the procedure, it is stated for how long to heat the magnesium, but as the lab went on, it is realized that the magnesium had to be heated for a longer time. This could mean that the magnesium could have been not heated long enough or too little for it to be fully converted into the magnesium oxide product effecting the final results of the lab by having smaller

2. When the magnesium ignited, removed it from the flame and held it over an evaporating dish or a pyrex watch glass until the metal had burned completely. Let the product fall into the evaporating dish.

The Grignard reaction is an important synthetic process by which a new carbon to carbon bond is formed. Magnesium metal is first reacted with an organic halide forming the Grignard reagent. The Grignard reaction is the addition of an organomagnesium halide (Grignard reagent) to a ketone or aldehyde, to form a tertiary or secondary alcohol, respectively. For example, the reaction with formaldehyde leads to a primary alcohol. Grignard Reagents are also used in the following important reactions: The addition of an excess of a Grignard reagent to an ester or lactone gives a tertiary alcohol in which two alkyl groups are the same, and the addition of a

The Grignard reagent can be made through adding the halogenolkane to small pieces of magnesium in a flask that contains diethyl ether. The lone pair electrons from two ether molecules form a complex with the magnesium in the Grignard reagent to stabilize the organometallic compound in order to increase the reagents’ ability to react. The mixture in the flask was warmed over a water bath for 30 minutes after the flask has been fitted to a reflux condenser. Everything should have remained dry with minimal exposure to air because Grignard reagents react with water. If this happens, the final results can be contaminated.

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.

5.3 mL of bromobenzne and 15 mL of anhydrous ether was then placed into the separatory funnel and was shaken and vented in order to mix the solution. Half of the bromobenzene solution was added first into the round bottom flask and as soon as a color change was observed, the remaining half of the bromobenzene was added drop wise into the round bottom flask. The mixture was then refluxed on a heating mantle for 10 minutes until most of the magnesium has been consumed.

The first experiment is about the combustion of magnesium after which the ash is formed.

Howard A. Zimmerman, although a little strange, was a normal everyday guy. However, he did not have many friends because he lived much of his life in the laboratory. His fascination with mixing and testing the various elements on the periodic table went far beyond a job, it was an obsession. A little over a year ago, Howard accepted a job at Rex Industries in Toronto, Canada. It was an exciting opportunity for Howard because he had never traveled outside the United States. He could not pass up the opportunity to test magnesium, which happened to be his favorite element. Magnesium is found in the earth's crust and is the eighth most abundant element but does not occur uncombined in nature. At room temperature magnesium will become a solid. He

Why did the magnesium not begin reacting immediately after you placed it into the tube? What action was required in order to start the reaction?

It is expected that the concentration of hydrochloric acid will increase the rate of the reaction between magnesium ribbon and hydrochloric acid. By increasing the concentration of