The Grignard reaction is a robust organic synthesis method for creating carbon-carbon bonds. One application of Grignard reagents is their use in activating nitrous oxide, a compound initially thought to be inert towards Grignard reagents—Tskhovrebov, et al. show that primary and secondary aliphatic Grignard reagents readily react with nitrous oxide to form hydrazones.1 Grignard reagents can also be used in cross-coupling reactions (iron) involving alkenyls/aryl carboxylates to create good carboxylate electrophiles, as elucidated by Li, et al.2 Figure 1: Preparation of Grignard Reagent (Phenylmagnesium Bromide)
In this experiment, a Grignard reagent was prepared using bromobenzene and magnesium in diethyl ether (Figure 1). An aprotic solvent (diethyl ether) was used because Mg0 reacts readily with protic solvents to form Mg2+. Figure 2: Formation of 1,1-Diphenylethanol with Grignard Reagent
Afterwards, the Grignard reagent was added to acetophenone to form 1,1-diphenylethanol. Ammonium chloride was added to protonate the oxyanion (acid workup).
Results and Discussion
Figure 3: Grignard Reaction Mechanism
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First, the reaction was conducted using clean, dry glassware in an inert atmosphere (anhydrous ether) to minimize side reactions involving the Grignard reagent. In particular, water can react with the Grignard reagent (very basic) to form benzene and magnesium hydroxide bromide: C6H5MgBr + H2O → C6H5 + MgOHBr. We also added acetophenone to the Grignard reagent dropwise because the reaction was very exothermic; a noticeable amount heat was produced (Figure 3). After forming 1,1-diphenylethanol, we washed the crude sample (1,1-diphenylethanol with impurities) with cold hexane to remove impurities such as acetophenone and bromobenzene. Cold hexane was added (rather than ambient temperature hexane) to minimize 1,1-diphenylethanol
Then the reaction tube was capped but not tightly. The tube then was placed in a sand bath reflux to heat it until a brown color was formed. Then the tube was taken out of the sand bath and allowed to cool to room temperature. Then the tube was shaken until a formation of a white solid at the bottom of the tube. After formation of the white solid, diphenyl ether (2 mL) was added to the solution and heated until the white solid was completely dissolved in the solution. After heating, the tube was cooled to room temperature. Then toluene (2 mL) was added to the solution. The tube was then placed in an ice bath. Then the solution was filtered via vacuum filtration, and there was a formation of a white solid. Then the product was dried and weighed. The Final product was hexaphenylbenzene (0.094 g, 0.176 mmol,
Enantiomers, a type of isomer, are non-superimposable, mirror images of each other. Diasteriomers, another type of isomer, are non-superimposable, non-mirror images of each other. Dimethyl maleate and dimethyl fumarate are diasteriomers, as they are not mirror images but instead vary in the orientation of the carbomethoxy groups around the double bond. Dimethyl maleate is the cis-isomer because both groups are on the same side and dimethyl fumarate is the trans-isomer because the two groups are on opposite sides. A bromine free radical mechanism was required for this conversion. First, energy from light is required to create two bromine free radicals from Br2. Then one of the free radicals attacks the double bond in dimethyl maleate, breaking it and creating a carbon radical on the other carbon. The bond then rotates and reforms, freeing the bromine radical and creating the trans-isomer, dimethyl fumarate. Bromine in this reaction is acting as a catalyst in this reaction and then cyclohexane is added at the end to neutralize the bromine free radicals. The activation reaction of the radical reaction is lower than the activation energy of the addition reaction, which is why it occurred more quickly. This reaction was successful because the percent yield was 67.1%, which is greater that 65%. It also demonstrated the expected principles, as the reaction did not occur without the presence of both light and bromine. The dimethyl fumarate had a measured boiling point of 100C to 103C, which is extremely close to the expected boiling point of 102C to
Wittig reactions allow the generation of an alkene from the reaction between an aldehyde/ketone and an alkyl halide (derived from phosphonium salt).The mechanism for the synthesis of trans-9-(2-phenylethenyl) anthracene first requires the formation of the phosphonium salt by the addition of triphenylphosphine and alkyl halide. The phosphonium halide is produced through the nucleophilic substitution of 1° and 2° alkyl halides and triphenylphosphine (the nucleophile and weak base). An example is benzyltriphenylphosphonium chloride, which was used in this experiment. The second step in the formation of the of the Wittig reagent, which is primarily called a ylide and derived from a phosphonium halide. In the formation of the ylide, the phosphonium ion in benzyltriphenylphosphonium chloride is deprotonated by the base, sodium hydroxide to produce the ylide as shown in equation 1.
Triphenylmethyl Bromide. A 400 mL beaker was filled with hot water from the tap. Acetic acid (4 mL) and solid triphenylmethanol (0.199 g, 0.764 mmol) were added to a reaction tube, with 33% hydrobromic acid solution (0.6 mL) being added dropwise via syringe. The compound in the tube then took on a light yellow color. The tube was then placed in the beaker and heated for 5 minutes. After the allotted time, the tube was removed from the hot water bath and allowed to cool to room temperature. In the meantime, an ice bath was made utilizing the 600 mL plastic beaker, which the tube was then placed in for 10 minutes. The compound was then vacuum filtered with the crystals rinsed with water and a small amount of hexane. The crude product was then weighed and recrystallized with hexane to form fine white crystals, which was triphenylmethyl bromide (0.105 g, 0.325 mmol, 42.5%). A Beilstein test was conducted, and the crystals produced a green to greenish-blue flame.
The goal of this lab is to exemplify a standard method for making alkyne groups in two main steps: adding bromine to alkene groups, and followed by heating the product with a strong base to eliminate H and Br from C. Then, in order to purify the product obtained, recrystallization method is used with ethanol and water. Lastly, the melting point and IR spectrum are used to determine the purity of diphenylacetylene.
Benzyl bromide, an unknown nucleophile and sodium hydroxide was synthesized to form a benzyl ether product. This product was purified and analyzed to find the unknown in the compound. A condenser and heat reflux was used to prevent reagents from escaping. Then the solid product was vacuum filtered.
In this experiment, four elimination reactions were compared and contrasted under acidic (H2SO4) and basic (KOC(CO3)3) conditions. The acid-catalyzed dehydration was done on 2-butanol and 1-butanol; a 2ᵒ and 1ᵒ alcohol, respectively. The base-induced dehydrobromination was performed on 2-bromobutane and 1-bromobutane; isomeric halides. The stereochemistry and regiochemistry of the four reactions were analyzed by gas chromatography (GC) to determine product distribution (assuming that the amount of each product in the gas mixture is proportional to the area under its complementary GC peak. The three butene products have been verified that they elute in the following order: 1-butene, trans-2-butene, and cis-2-butene.
In this two week project, an experiment was designed and tested. The experiment was performed to tested how a variable affects the E/Z ratio products of a Wittig reaction.
Abstract In this experiment methyl-3-phenyl-2-propenoate was prepared using a Wittig reaction. Benzaldehyde and methyl (triphenylphosphoranylidene) acetate were used to give a final product. 0.33g of methyl3-phenyl-2-propenoate was found at the end of the experiment therefore the percentage yield of methy-3-phenyl-2-propenoate is 62%. The Rf value of benzaldehyde was found to be 0.85.
The formation of quinone is especially enticing, as it is more stable to the photooxidation, comparing to acenes. Anthraquinone can be easily reduced to the target molecule or it can be functionalized in the exact position which is especially important for the tetracenes
Ishaan Sangwan Experiment 7: Grignard Reaction Discussion In this experiment, a Grignard reaction was performed to create a carbon-carbon bond, between a bromide and carbon dioxide. The product was then protonated to form a carboxylic acid, which was identified by obtaining its melting point, and by performing a titration with NaOH to obtain its molecular weight. In organometallic chemistry, carbon is bound to a metal.
The Examination of Chemical Reactions in Multiple Chemical Compounds to Identify Types of Energy Changes and Types of Reactions The purpose of this lab is to investigate chemical reactions that takes place between different chemical compounds. The products formed through these reactions will be observed for physical properties and chemical changes. Pour 100 mL of citric acid into an Erlenmeyer flask. Fill a clay crucible with baking soda.
Falak Mdahi Chem 203.2 The Synthesis of Acetanilide from Acetic Anhydride and Aniline Introduction Recrystallization is a technique used to purify solids that contain small amounts of impurities. It is used to isolate pure solids from a supersaturated solution, leaving the impurities in the solvent (1). The solid containing the impurities is placed in a hot solvent and upon cooling the compound precipitates to its purified form while the impurities are left behind in the solvent (1). There are six steps when it comes to undergoing a recrystallization of a solid.
Thickett, Geoffrey. Chemistry 2: HSC course. N/A ed. Vol. 1. Milton: John Wiley & Sons Australia, 2006. 94-108. 1 vols. Print.
In homogeneous catalysis, oxidation of alcohols to corresponding aldehyde and ketone requires a stoichiometric amount of oxidant such as chromium(VI), permanganate, DMSO and DDQ (Cardona and Permeggiani, 2015). Consequently, all of these oxidants suffer drawbacks of generating high amounts of organic and inorganic toxic side products after the reaction. Furthermore, these methods are usually carried