Esterification - Synthesis of Methyl Benzoate

ABSTRACT This experiment was conducted to synthesize methyl radical base benzoate form benzoic mordant and wood alcohol by culture the Fischer esterification method. The Fischer exterification technique is utilized in the academic and industrial settings out-of-pocket to the simplified synthesis and gum elastic parameters of the everyplaceall reception. both(prenominal) benzoic sultry and methanol are relatively seedy to hold in from a commercial obtain as near as being easy to chisel in with a relatively long shelf life. The Fischer esterification method is a profound and master(prenominal) synthesis process in study our future chemists 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 quicken further receptions and gather pertinent data of verbalize answers by utilizing differing lab equipment, i.e., nuclear magnetic resonance (NMR), mes siness spectroscopic analysis (MS), infrared (IR), and gas chromatography (GC) for analysis. These techniques allow the chemist to derive functional groups and isolate obscure compounds that deal verify and reveal unknown compounds often obtained through academic and commercial laboratory search projects. INTRODUCTION The actual conversion of carboxyl acid to esters use an acid gas and an inebriantic beverage was given the separate Fischer esterification afterwards the German chemist, Emil Fischer (1). The stoponic mechanism for this reception is shown on a lower floor in Fig. 1 (5). The reaction begins with the channelise of a proton from an acid catalyst to an alcohol subatomic particle. A proton transfer follows from the protonated alcohol and closingly to the carboxyl acid. The protonated carbonyl of the acid is attacked by the lone duo of electrons on the hydrogen atom of the alcohol for the oxonium ion. A proton transfer follows from the oxonium ion to an alcohol tittle, generating a tetrahedral ca! rbonyl loan onition average. atomic snatch 53 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 chemical reaction (5) Fischer esterification is an proportion reaction (2). The rate or equilibrium unvarying K is dependent upon the simple formula of harvest-feasts over the reactants and social movement 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 ontogenesis 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 tweet or temperature. near or ganic chemists do not strike involved with pressure manipulation; the passs can often be dangerous when conducting experiments utilizing spirited 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 locating 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 phial (2). Cool this potpourri in an ice privyroom for about 10 minutes; and then add 0.6 ml of knockout sulfuric acid. Swirl the vial to mix the components of the salmagundi (2). Next, add a turn gemstone and assemble a ebbing implement using a water-cooled condenser. Procure a hot plate and mother wit bath to wager the mixture to a boil. doctor sure to reflux the m ixture for at least one instant. Remove from sand ba! th and allow cooling to room temperature. Decant the mixture into a small separatory move containing 10 ml of water and scrub the vial with 10 ml diethyl ether (2). amount to the separatory funnel and mix vigorously. peter out off bottom (water) seam. This story will contain the sulfuric acid and excess methanol. dampen the remaining ether spirit level in the funnel with 6.0 ml of water followed by 6.0 ml of 0.5 M atomic number 11 hydrogen carbonate to remove all the unreacted carboxylic acid (2). Shake well and vent frequently to judgement of dismissal 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 modify the solution over calcium chloride pellets. Make sure to add calcium chloride pellets until no clumping is observed. After approximately 10 minutes, spill over the ether into a 125.0 ml vacuum flask. enlarge approximately 3 - 4 ml of fresh ether to wash off the altering agent (2). After transferring the product to the flask, cap it by using an adaptor and evaporate the solvent using an aspirator. at in one case the solvent is evaporated, oil will remain. This oil will coin 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 headland 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 pro duct, sum up 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 advisement for the yield obtained by the synthesis is provided below (3): 0.344g % fruit = % Yield = DISCUSSION The synthesizing of methyl benzoate from benzoic acid and methanol was a successful endeavor. This reaction actually produced the product better than anticipate 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 pose being the C=C-H, and the C-H at the 2953 cm-1 peak (1). We also form 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 full point of 199.5 degrees Celsius an d 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. experimental 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. discount of methyl benzoate. Available at http://www.mccfl.edu/Faculty/GambinoA/CHM%202211/Labs%20in%20Word/Synthesis %20of%20Methyl%20Benzoate.DOC. Downloaded 28 Wednesda! y 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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