Esterification - Synthesis of Methyl Benzoate

ABSTRACT This experiment was conducted to synthesize methyl radical separate benzoate form benzoic mordant and methanol by education the Fischer esterification method. The Fischer exterification technique is utilized in the academic and industrial settings cod to the simplified synthesis and gum elastic parameters of the oerall reception. both(prenominal) benzoic harsh and methanol are relatively two-a-penny to puzzle from a commercial obtain as hygienic as being easy to chisel in with a relatively long shelf life. The Fischer esterification method is a rudimentary and master(prenominal) synthesis process in study our future druggists in both commercial and academic physical exercise and principles. By utilizing this method of synthesis, the chemist has the knowledge to utilize sure chemicals to lease further receptions and gather pertinent data of verbalize responses by utilizing differing lab equipment, i.e., nuclear magnetic resonance (NMR), messi ness spectroscopy (MS), infrared (IR), and gas chromatography (GC) for analysis. These techniques allow the chemist to derive operative groups and isolate unacknowledged compounds that deal verify and reveal unknown compounds often obtained through academic and commercial laboratory look for projects. INTRODUCTION The actual conversion of carboxyl acid to esters victimization an acid gas and an intoxi keeptic beverage was given the reveal Fischer esterification afterwards the German chemist, Emil Fischer (1). The grassroots mechanism for this response is shown infra in Fig. 1 (5). The reaction begins with the manoeuvre of a proton from an acid catalyst to an alcohol subatomic particle. A proton transfer follows from the protonated alcohol and closingly to the carboxylic acid. The protonated carbonylic of the acid is attacked by the lone dyad of electrons on the hydrogen atom of the alcohol for the oxonium ion. A proton transfer follows from the oxonium ion to an al cohol tittle, generating a tetrahedral carb! onyl loanition average. oneness of the OH groups I the intermediate abstracts a proton from the protonated methanol molecule to form a genuinely good leaving group, which is peeing. In the final examination step, the methanol molecule abstracts a proton form the protonated carbonyl to regenerate the carbonyl and whquintessence molecule is displaced. The final crossing is the ester. Fig. 1 Mechanism of reception (5) Fischer esterification is an proportion reaction (2). The rate or equilibrium unremitting K is dependent upon the simple formula of harvest-festivals over the reactants and drive out be manipulated by the basic principles of Le Chatlier (2). One can add or decrease the rate of the reaction by using these basic principles. One can plus the cheaper reactant such as an alcohol (methanol in our reaction), remove a product, such as water, using the Dean Stark frame-up, or one can manipulate the stuff or temperature. about organic chemists do not shorten in volved with pressure manipulation; the passs can often be dangerous when conducting experiments utilizing gamy pressures. Manipulating the reaction using these different principles will allow the chemist to exit much of the ester compound by maximizing the reaction potential. The fact that the reaction is an equilibrium reaction opens the door for brass product such as reactants being isolated in the final product as well. The reaction has the ability to go both ways. MATERIALS AND METHODS Place 2.0 g of benzoic acid and 5.0 ml of methanol in a 10.0 ml conical vial (2). Cool this potpourri in an ice canroom for nearly 10 minutes; and then add 0.6 ml of laborious sulfuric acid. Swirl the vial to mix the components of the kind (2). Next, add a change state gemstone and assemble a reflux setup using a water-cooled condenser. Procure a hot plate and mother wit bath to contribute the mixture to a boil. doctor sure to reflux the mixture for at least one instant. Remo ve from sand bath and allow cooling to room temperatu! re. Decant the mixture into a small separatory move containing 10 ml of water and cleanse the vial with 10 ml diethyl ether (2). amount to the separatory funnel and mix vigorously. peter out off bottom (water) seam. This degree will contain the sulfuric acid and excess methanol. lave the remaining ether stratum in the funnel with 6.0 ml of water followed by 6.0 ml of 0.5 M atomic reckon 11 hydrogen carbonate to remove all the unreacted carboxylic acid (2). Shake well and vent frequently to put out pressure. Repeat the bicarbonate race process until the solution is basic when testing with pH paper. Drain the bicarbonate layer into a 50.0 ml beaker, then swear out the ether layer with a few milliliters of saturated sodium chloride solution, then ironic the solution over calcium chloride pellets. Make sure to add calcium chloride pellets until no clumping is observed. After well-nigh 10 minutes, pour the ether into a 125.0 ml vacuum flask. enlarge approximately 3 - 4 m l of fresh ether to disinfect the modifying agent (2). After transferring the product to the flask, cap it by using an adaptor and evaporate the solvent using an aspirator. at at a time the solvent is evaporated, oil will remain. This oil will reach to be purified by distillation. Set up the Hickman Still apparatus and air condenser and place the apparatus in a sand bath to heat the oil until it boils (2). The boiling captain of ester is approximately 199 degrees Celsius; collect all material boiling preceding(prenominal) that temperature (2). Pre-weigh a conical vial and transfer the distillate. After weigh the product, foretell the percent yield and take the product to the IR to obtain a spectrum of the pure product (2). DATA AND RESULTS As a result of the Fischer esterification process, 0.344 g of methyl benzoate was recovered for the final product. The count for the yield obtained by the synthesis is provided below (3): 0.344g % return key = % Yield = DISCUSSION T he synthesizing of methyl benzoate from benzoic acid ! and methanol was a successful endeavor. This reaction actually produced the product better than evaluate in a laboratory setting. Based on the I.R. spectra obtained; we can conclude that we had form the product. The first peak was in the 3066 cm-1 swear being the C=C-H, and the C-H at the 2953 cm-1 peak (1). We also bring the C=O peak at 1725 cm-1 along with the C=C at 1602 and C-O-C at the 1279 cm-1 range (2). This structure verifies our final product of methyl benzoate. We recovered 0.344 g of the final product (methyl benzoate) for a 15.46% final yield. Methyl benzoate has a boiling address of 199.5 degrees Celsius and a molecular weight of 136.15 grams per mole (3). With a boiling point this high, it was important to reflux for the entire hour. We refluxed for just over one hour and then allowed it to cool to room temperature. At this point we utilize the separatory funnel to separate our products and wash, then dry by evaporating the semiliquid on the hot plate. REFERENCES 1.Fischer, E. Available at hypertext transfer communications protocol://www.nobel.se/interpersonal chemistry/laureates/1902/fischer-bio.html. Downloaded 28 Wednesday 2004. 2.Salvatore RN, Jung KW. data-based organic chemistry: A unreal & mechanistic perspective. 222 Berkley St. capital of Massachusetts: Houghton Mifflin; 1999. 102 p. 3.Density and formula weight of methanol. Available at hypertext transfer protocol://chemfinder.canbridgesoft.com/result.asp. Downloaded 28 Wednesday 2004. 4. price reduction of methyl benzoate. Available at http://www.mccfl.edu/Faculty/GambinoA/CHM%202211/Labs%20in%20Word/Synthesis%20of%20Methyl%20Benzoate.DOC. Downloaded 28 Wednesday 2004. 5.Mechanism of reaction. Available at http://www.chem.ubc.ca/courseware/260/Reactions_Acids_and_amides.pdf. Downloaded 28 Wednesday 2004. If you want to get a full essay, club it on our website: OrderEssay.net

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