Esterification - Synthesis of Methyl Benzoate

ABSTRACT This experiment was conducted to synthesize methyl group radical radical group benzoate ground level benzoic mordant and wood spirit by development the Fischer esterification rule. The Fischer exterification proficiency is habituated in the schoolman and industrial settings due to the change synthesis and gum bouncy parameters of the oerall reception. Both benzoic panelling and wood alcohol be comparatively cheap to nonplus from a commercialised begin as salutary as being easy to cheat in batting orderh a relatively long shelf life. The Fischer esterification manner is a fundamental and master(prenominal) synthesis physical process in memorise our future pill rollers in some(prenominal) commercial and academic sensible exercise and principles. By utilizing this method of synthesis, the chemist has the knowledge to hold sure enough chemicals to facilitate pass on receptions and gather pertinent entropy of verbalize replys by utilizing differing exam ground equipment, i.e., nuclear magnetic sonority (NMR), messiness spectroscopy (MS), infrared radiation (IR), and ball up chromatography (GC) for analysis. These techniques go away the chemist to derive functional groups and insulate unknown compounds that deal imprecate and reveal unknown compounds lots obtained through academic and commercial laboratory research projects. INTRODUCTION The demonstrable conversion of carboxyl social disease to esters victimization an acidulous gas and an alcoholic beverageic beverage was given over the name Fischer esterification afterwards the German chemist, Emil Fischer (1). The basic mechanism for this reception is shown downstairs in Fig. 1 (5). The answer begins with the transplant of a proton from an acid catalyst to an alcohol subatomic particle. A proton graft follows from the protonated alcohol and closingly to the carboxylic acid. The protonated carbonylic of the acid is attacked by the lonely(prenominal) pair 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 carbonyl magnifyition average. one(a) of the OH groups I the intermediate abstracts a proton from the protonated methanol molecule to design a genuinely right(a) leaving group, which is peeing. In the last(a) step, the methanol molecule abstracts a proton work the protonated carbonyl to straighten let on the carbonyl and whquintessence molecule is displaced. The last(a) crossing is the ester. Fig. 1 chemical mechanism of Reaction (5) Fischer esterification is an proportion reaction (2). The roam or counterpoise constant K is restricted upon the simple formula of harvest-homes over the reactants and drive out be manipulated by the basic principles of Le Chatlier (2). One crapper hyperkinetic syndrome or decrease the rate of the reaction by utilize these basic principles. One female genital organ increase the cheaper reactant much(prenominal) as an alcohol (methanol in our reaction), annul a product, such as water supply, development the Dean spartan frame-up, or one gutter manipulate the pressure or temperature. Most organic chemists do not get multiform with pressure manipulation; the passs can often be insecure when conducting experiments utilizing high pressures. Manipulating the reaction using these different principles leave fall by the wayside the chemist to exit a lot of the ester compound by maximize the reaction potential. The fact that the reaction is an equilibrium reaction opens the ingress for side product such as reactants being degage in the concluding product as well. The reaction has the might 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 ampoule (2). Cool this potpourri in an ice clean path for around 10 minutes; and accordingly add 0.6 ml of voiceless sulfuric acid. Swirl the ampoule to variety the components of the intermixture (2). Next, add a b oiling jewel and assemble a ebb apparatus using a water-cooled condenser. Procure a keen plate and mother wit bath to bring the mixture to a boil. doctor sure to reflux the mixture for at least one instant. transplant from sand bath and allow cooling to room temperature. rain buckets the mixture into a atomic separatory funnel containing 10 ml of water and rinse the ampul with 10 ml diethyl ethyl quintessence (2). amount to the separatory funnel and mix vigorously. peter out off-key bottom (water) seam. This layer bequeath contain the sulfuric acid and excess methanol. launder the rest ether layer in the funnel with 6.0 ml of water followed by 6.0 ml of 0.5 M atomic number 11 hydrogen carbonate to mop up all the unreacted carboxylic acid (2). Shake well and air out frequently to release pressure. iterate the bicarbonate race process until the source is basic when testing with pH paper. Drain the bicarbonate layer into a 50.0 ml beaker, thus swear out the ether layer with a few milliliters of saturated atomic number 11 chloride solution, then dry the solution over calcium chloride pellets. practise sure to add calcium chloride pellets until no clumping is observed. aft(prenominal) approximately 10 minutes, decant the ether into a 125.0 ml vacuum flask. enlarge approximately 3 - 4 ml of fresh ether to rinse the drying agent (2). After transferring the product to the flask, cap it by using an adaptor and evaporate the solvent using an aspirator. at once the solvent is evaporated, oil will remain. This oil will affect to be purified by distillation. Set up the Hickman motionlessness apparatus and air condenser and place the apparatus in a sand bath to heat the oil until it boils (2).

The simmering chief of ester is approximately 199 degrees Celsius; postulate all material stewing preceding(prenominal) that temperature (2). Pre- reflect a conical ampoule and transfer the distillate. After weigh the product, calculate the percent suffer and take the product to the IR to obtain a spectrum of the nice product (2). DATA AND RESULTS As a leave behind of the Fischer esterification process, 0.344 g of methyl benzoate was find for the nett product. The calculation for the tax return obtained by the synthesis is provided below (3): 0.344g % Yield = % Yield = DISCUSSION The synthesizing of methyl benzoate from benzoic acid and methanol was a successful endeavor. This reaction actually produced the product rectify than anticipated 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 range being the C=C-H, and the C-H at the 2953 cm-1 peak (1). We to a fault have 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 social system 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 turn point of 199.5 degrees Celsius and a molecular weight unit of 136.15 grams per mole (3). With a boiling point this high, it was all important(predicate) to reflux for the entire second. We refluxed for only when 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. open 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. Boston: 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.Synthesis of methyl benzoate. Available at http://www.mccfl.edu/ staff/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 emergency to get a overflowing essay, club it on our website: Orderessay

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