INTRODUCTION The purpose of this experiment involved synthesis of diphenylmethanol using phenylmagenisum bromide and benzaldehyde, using the method called Grignard reaction. Grignard reactions are an important method for new carbon-carbon bond formation as well as for the synthesis of alcohols. In Grignard reaction, when an alkyl or aryl halide, R-X where “X” is a halogen atom (i.e. Cl, Br, I) is reacted with organometallic compound such as magnesium, Mg. It forms a product RMgX which is known as Grignard reagent. The Grignard reagent formation always undergoes through dry anhydrous ether solvent due to its ability to act as Lewis base (donates pair of electrons) which is necessary to solvate and stabilize the RMgX Grignard reagent. In this experiment, the aryl halide bromobenzene was reacted with magnesium turnings in anhydrous diethyl ether solvent to form the Grignard reagent, phenylmagenisum bromide. It is very important and necessary that all reagent, solvent and glassware that were used were dry because even a small amount of water can react violently and form a hydrocarbon and wipe out the Grignard reagent. Once the reagent is formed it is further synthesized and then reacted with aldehyde or ketone to form a secondary or tertiary alcohol respectively, through its carbonyl group. For this …show more content…
experiment, phenylmagenisum bromide was reacted with an aldehyde, i.e.
benzaldehyde to synthesize after protonation into diphenylmethanol which is a secondary alcohol. This reaction takes place due to the nucleophilic carbonyl group
that can attack the electrophilic bonds on the Grignard reagent. Lastly, melting point and percentage yield of diphenylmethanol was measured, calculated and compared to the expected melting point found in literature as to how effective was the experiment in synthesizing the pure diphenylmethanol. Step 1: Formation of the Grignard reagent phenylmagenisum bromide Step 2 and 3: The Grignard reagent attacks a carbonyl compound benzaldehyde (step 2) and after the step 2, water is added to be protonated and form secondary alcohol, i.e. diphenylmethanol final product (step3). Grignard Reaction Mechanisms Steps involving Phenylmagenisum bromide with benzaldehyde to synthesize diphenylmethanol (Figure1.0). RESULTS In this experiment, the formation of Grignard reagent was indicated by the appearance of cloudiness in the solution when bromobenzene and magnesium was reacted in anhydrous diethyl ether along with heat forming phenylmagenisum bromide (Grignard reagent). It took approximately 15 minutes for 0.4 g magnesium pieces to dissolve completely to form phenylmagenisum bromide. After this the solution was reacted with 1.5 mL of benzaldehyde in 4 mL anhydrous diethyl ether a vigorous fizzed was observed as well the solution had turn into light pink color. After the solution was cooled, 5 mL of water was added along with 20% HCl was added, it was observed that the solution had two layers white/clear layer and yellow green layer. The solution was then washed by removing the white aqueous layer and keeping the yellow green layer. The yellow greenish color solution was the final product, diphenylmethanol formed. This solution was heated and suction-filtered, giving a white crystallize product of diphenylmethanol. The crystallized mass weigh was 0.99 g and its measured melting point was 59.9⁰C – 67.8⁰C. Table 1: Physical properties values of the compounds used within the experiment Name of the Compound Molecular Weight (g/mol) B.p ⁰C M.p ⁰C Density (g/mL) Mass (g) Volume (mL) mmol Theoretical yield % Bromobenzene 157.01 156 - 1.5 2.7 1.8 17.2 - Benzaldehyde 106.12 178 - 1.04 1.56 1.5 14.7 - Magnesium 24.31 - - - 0.4 - 16.5 - Diphenylmethanol 184.24 298 65-67 - - - 14.7 100% Diethyl ether 74.12 34.6 - 0.706 - - - - Table 2: Observed, measured and calculated data of the experiment Actual mass (g) of diphenylmethanol Theoretical mass (g) of diphenylmethanol % yield of product Theoretical M.p ⁰C of diphenylmethanol Observed M.p ⁰C of diphenylmethanol 0.99 g 2.708 g 36.56% 65⁰C – 67⁰C 59.9⁰C – 67.8⁰C Percentage Yield Calculated Limiting reagent is benzaldehyde, 14.7 mmol. Therefore, 1.56 g benzaldehyde *(1 mol benzaldehyde/ 106.12 g benzaldehyde) is equal to 0.0147 mol. Theoretical mass of diphenylmethanol = 0.0147 mol * 184.24 g/mol = 2.708 g Percentage yield of diphenylmethanol = (actual mass/ theoretical mass)* 100% = (0.99 g/ 2.708g)* 100% = 36.56%
As a final point, the unknown secondary alcohol α-methyl-2-naphthalenemethanol had the R-configuration since it reacted the fastest with S-HBTM and much slower with R-HBTM. TLC was a qualitative method and ImageJ served as a quantitative method for determining which reaction was the faster esterification. Finally, 1H NMR assisted in identifying the unknown from a finite list of possible alcohols by labeling the hydrogens to the corresponding peaks.
The goal of this experiment is to determine which products are formed from elimination reactions that occur in the dehydration of an alcohol under acidic and basic conditions. The process utilized is the acid-catalyzed dehydration of a secondary and primary alcohol, 1-butanol and 2-butanol, and the base-induced dehydrobromination of a secondary and primary bromide, 1-bromobutane and 2-bromobutane. The different products formed form each of these reactions will be analyzed using gas chromatography, which helps understand stereochemistry and regioselectivity of each product formed.
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,
The goal of this two week lab was to examine the stereochemistry of the oxidation-reduction interconversion of 4-tert-butylcyclohexanol and 4-tert-butylcyclohexanone. The purpose of first week was to explore the oxidation of an alcohol to a ketone and see how the reduction of the ketone will affect the stereoselectivity. The purpose of first week is to oxidize the alcohol, 4-tert-butylcyclohexanol, to ketone just so that it can be reduced back into the alcohol to see how OH will react. The purpose of second week was to reduce 4-tert-butylcyclohexanol from first week and determine the effect of the product's diastereoselectivity by performing reduction procedures using sodium borohydride The chemicals for this lab are sodium hypochlorite, 4-tert-butylcyclohexanone
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.
Abstract: Various Anilines were tested with Br2/HBr solution, the products were crystallized and melting points attained to verify relative reactivity. My assignment, 2,4-Dibromoanisol, was prepared in a yield of 52% with a melting point of 55-58 C .
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.
Discussion The reaction of (-)-α-phellandrene, 1, and maleic anhydride, 2, gave a Diels-Alder adduct, 4,7-ethanoisobenzofuran-1,3-dione, 3a,4,7,7a-tetrahydro-5-methyl-8-(1-methylethyl), 3, this reaction gave white crystals in a yield of 2.64 g (37.56%). Both hydrogen and carbon NMR as well as NOESY, COSY and HSQC spectrum were used to prove that 3 had formed. These spectroscopic techniques also aided in the identification of whether the process was attack via the top of bottom face, as well as if this reaction was via the endo or exo process. These possible attacks give rise to four possible products, however, in reality due to steric interactions and electronics only one product is formed.
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.
The purpose of this experiment was to investigate the bromination of trans-cinnamic acid and determine what the isolated products tells us about the possible mechanism. The stereochemistry of the product results from either a syn or anti addition of Br2 to the alkene. Recrystallization using ethanol and water solvent mixture was used to purify the crude product and melting point was implemented in order to see which products were synthesized. The syn addition products (2S, 3S- and 2R, 3R) 2,3-dibromo-3-phenylpropanoic acid have a melting range of 93.5-95 ᵒC. The anti addition products (2S, 3R- and 2R, 3S) 2,3-dibromo-3-phenylpropanoic acid have a melting range of 202-204 ᵒC.
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.
The purpose of conducting this experiment was to synthesise and characterise for the preparation of benzocaine via a fishcer esterification reaction by the means of amino benzoic acid alongside ethanol. The product was also precipitated from a solution in order to gain a pH of 8.The secondary aim was to esterify the reaction in an equilibrium reaction catalysed via the addition of acid shown below:
In this experiment a Grignard reaction was carried out to give the desired reagents: benzyl magnesium chloride. This was achieved by reacting benzyl chloride with magnesium in ether. After the Grignard’s reagents were formed, it was reacted with benzaldehyde in ether to give 1,2-diphenylethanol. The main objective of this experiment was to synthesize 1,2-diphenylethanol via a Grignard reaction. The NMR proves that the right product was formed in this experiment.
Gas chromatography is a technique by which mixtures of volatile substances can be separated. Mass spectroscopy is a technique that analyses the mass of volatile molecules and their fragments. By using both techniques together, separated compounds are detected by their mass fragments. In this experiment, the CSUDH Chemistry Department Agilent 6890 N Gas Chromatograph, interfaced with an Agilent 5975B XL Mass Selective Detector was used. With this GC-MS machine, a mixture of compounds can be separated and detected by analyzing the mass spectrum data.