It condenses and returns into the reaction vessel 3. The side product has been produced is biphenyl which consists of two phenyl rings. In order to synthesis triphenylmethanol, Grignard reagent is playing an important role because Grignard reagent is the key reagent in this experiment. Diethyl ether prevents oxygen and carbon dioxide from reacting with the Grignard reagent once it is formed. After reflux, the Grignard reagent produced was cooled down in an ice bath in order to reduce its temperature. The melting point was found to be 98. Alkyl halides vary greatly in their rates of reaction with magnesium.
Our primary aim was to demonstrate the different techniques needed to isolate biosynthetic auxotrophic mutants using chemical, physical and transposon mutagenesis. For example, alkyl iodides generally react very rapidly, whereas most aryl chlorides react very slowly, if at all. The compounds that are polar covalent bonded are Grignard reagents and are useful in making carbon-carbon bonds and reducing carbonyls. Avoid contact with skin, eyes and clothing Hexane C6H14 -95°C 69°C 0. Reaction Scheme: Mechanism: The nucleophilic phenyl magnesium bromide attacks the electrophilic carbonyl of benzophenone to form a magnesium alkoxide. The reaction between methyl benzoate and Grignard reagent is showing in the following figure 6: Figure 6 Dissociation of magnesium alkoxide produces a ketone which tends to react further with more Grignard reagent.
This is considered as an organometallic compound which consists of the combination of a metal and organic molecule. A reflux apparatus was used to carry out most of the experiment. The solution was then poured into a 500 mL separatory funnel and the layers were allowed to separate. The formation of Grignard reagent is highly exothermic which will produce a lot of heat energy from the system. Ether or tetrahydrofuran are usually can be used as the anhydrous solvent in producing the particular reagent. The precipitate was then collected over a vacuum filtration system and the final product was allowed to dry for one week.
A small amount of iodine crystal was added directly into the magnesium surface if the reaction does not take place after 5-10minutes. From here, a melting point range of 147. Table of Reagents: Name Chemical formula Melting Point Boiling Point Density Safety Hazards Diethyl ether C4H10O -116. Off of the curved arm of the Claisen adapter, a 250 mL separatory funnel is then attached. Recrystallization of triphenylmethanol has been carried out to purify the product. If the water reacts with Grignard reagent, the decomposition of the particular reagent will occur. Figure 1 in below shows the general reaction mechanism for the formation of Grignard reagent.
This is to prevent the immediate addition of solvent from evaporating quickly due to high temperature of Grignard reagent if cooling down process is not taken. My most memorable experiences in biology were in the lab. So, the solvent used in the experiment must not contain any water such as diethyl ether since it is a water free solvent. As the result, the reaction synthesizes an alcohol, triphenylmethanol and magnesium salt water soluble. The iodine crystal was added into the magnesium surface because the heats from water bath or palm were not enough to initiate the reaction. The ether layer was dried over sodium sulfate anhydrous and filtered with cotton wool. The reaction proceeds via a radical electron transfer.
So, several precaution steps must be taken in the procedures to avoid the Grignard reagent reacts with water: the reaction flask is dried in the oven before use; iodine is vaporized in the flask tie up traces of water and to activate the surface of magnesium; the anhydrous diethyl ether should be used. Once the reaction was initiated and the formation of Grignard reagent became steady, the ether refluxed itself. The mixture is stirred with a magnetic stirrer. The carbonyl carbon of methyl benzoate was attacked by the nucleophilic carbanion during reflux. The biphenyl is known as impurity in the experiment. After the solution was run through the hot gravity filter, the flask was placed on the windowsill in order to cool down the solution.
A recrystallization was performed to purify the Grignard product by dissolving the product in methanol. It undergoes reduction to triphenylmethane by 9, l0-dihydro-10-methylacrid ine in the presence of perchloric acid. Modifications of the procedure included adding an additional 1. Methanol was then heated on a steam bath until boiling and enough methanol was added to the flask containing the triphenylmethanol to completely dissolve the solid in the flask. The nucleophilic Grignard reagent attacks an electrophilic carbon, which results in the formation of a carbon-carbon bond. The organometallic grignard reagent was synthesized by use of a reflux apparatus recrystallization techniques.
The purpose of this lab report is to provide… Kimmi Dodia- Biomedical Science- 1019971 Lab partner- Kim Harcourt Lab report- Experiment 1: Microbial Genetics Abstract The objective of this experiment was to introduce the study of bacterial genetics in order to identify the potency of different mutagenic agents. Alternatively, the iodine crystal was added instead of increasing the temperature that supplied to the system in order to prevent the explosion since diethyl ether is highly flammable. 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. From here, a melting point range of 147. The final product was solidified and recrystallized and spectral data was obtained to confirm its presence. General description Triphenylmethanol forms 1:1 molecular complex with triphenylphosphine oxide. The impurity can be removed from the product through a method of recrystallization since biphenyl is much more soluble in ligroin compared to triphenylmethanol.
It was important that water be excluded from the reaction, in order to prevent the formation of benzene. A stirring rod was then used to dislodge any solid that was stuck to the bottom of the round bottom flask. Carbon is not stable therefore it is very reactive as it more nucleophilic. Therefore, petroleum ether was used in the experiment in order to let the biphenyl dissolved in it so that this side product can be removed via recrystallization. The Grignard reagent can be dissociated to form negatively charged carbanion which attacked the carbonyl carbon with partial positively charged. The melting point range obtained from the final product was 89-91°C which was much lower than the literature value of 160-163°C.
The metal is less electronegative than the carbon, so the carbon bears a partial negative charge. The triphenylmethanol was purified by recrystallization. This causes the formation of partial positively charge and partial negatively charge on the magnesium atom and alkyl or aryl group respectively. Introduction: The Grignard reagent is an effective reducing agent that may be used to reduce a ketone to an alcohol. Figure 3 The figure 3 above shows the Grignard reagent and water reaction. Figure 5 Once the Grignard reagent is readily formed, the carbonyl compound has been introduced into the reagent in order to synthesis the expected product. By the way, here is the structure meant to be placed above -.