The Nitration Of Methyl Benzoate Biology Essay

The Nitration Of Methyl Benzoate biology EssayMethyl Benzoate is electron rich and thus undergoes electrophilic aromatic substitution. Nitration of methyl radical group benzoate get out form a major result, methyl m-nitrobenzoate that was foster purified by re-crystallization. The electrophile or the nitronium ion attached to the meta ready in the benzene hoop because of the carboxylic group cosmos meta-deactivator that made the reaction took place in the meta position and the ortho and para positions are de stabilize. The citizenry of re-crystallized methyl m-nitrobenzoate was resolute to be 0.257 g compared to the vision of methyl benzoate, 0.360 g that resulted to % yield. The melting point of the methyl m-nitrobenzoate resulted to 74C compared to its true melting point 78C was computed to cook 5.13% divergency. Many side-products like different orientations in the benzene cry go away be form during chemical reactions. To see how much were organise and how gro ss(a) was the product was, its TLC Profile was calculated that resulted into Rf = 0.79 wherein the result from single vaporization indicating that the product synthesized was pure. The results of the experiment are therefore accurate and effectual in familiarizing with reactions and mechanisms that occur during nitration.__________________________________________________________________________INTRODUCTIONAromatic hydrocarbons are heightens with unmatchable or more(prenominal) benzene rings (3). Due to electron delocalization by its alternating double bonds, it is characterized by being more changeless compared to alkenes (2). Benzene, being aromatic, is a cyclic compound, an unsaturated compound due the presence of pi bonds. In contrast to the double bonds causing the unsaturation of benzene, it is strong and unreactive because of its vibrancy structure where there is rearrangement of electron duo. They undergo EAS or Electrophilic Aromatic renewal reaction due to the fac t that they are electron rich. The nitration of methyl benzoate, C6H8O2, undergoes such(prenominal) type of reaction with concentrated nitric social disease and sulfuric sexually transmitted disease to yield methyl m-nitrobenzoate. From the methyl benzoate, methyl m-nitrobenzoate volition be formed and volition undergo purification by re-crystallizing with methanol. Thin Layer Chromatography pen and melting point of the product were used in the experiment to create sure that there are no by-products formed like compounds with o- and p- orientation (2).MATERIALS AND METHODSThe mass of conical flask was determined and added with 20 drops of methyl benzoate. The mass was also determined as well as the mass of methyl benzoate itself. The methyl benzoate in the flask was placed in an wish-wash lavatory while added by 2 ml of conc. H2SO4 while swirling. Then, the nitrating agent was brisk which is a alloy of 1 ml conc. HNO3 and 1 ml conc. H2SO4 chilled in an grump bath. The n itrating agent was then added to the methyl benzoate solution using a Pasteur pipet. The florilegium was constantly stirred and still chilled in an ice bath. However, conc. H2SO4 essential be added if cloudiness occurs to change the mixture into its clear appearance. Furthermore, the reaction mixture was added 10 g of crushed ice then stirred. As the ice melted, the solid product formed was separated using vacuum filtration where a filter paper was folded into 1/16 big enough to overcome holes in the Buchner funnel. Then, the product was serve with coolness distilled water, fol embarrasseded by 5% NaHCO3 and with cold distilled water until the filtrate became neutral.The product was transferred in a watch field glass and dried over a steam bath. Methanol was used to recrystallize or solidify the product and the percentage yield was calculated. The melting point of the recrystallized product was determined using the melting point apparatus. The TLC profile was determined using a TLC carapace. The TLC plate was drawn with a line using a pencil 1 cm from the target and from the top then dipped in a beaker with ethyl acetate. The plate was dipped in ethyl acetate 3 times. When the response reached the former(a) edge (the some other line), the plate was removed from the beaker. Lastly, Iodine pellets were used to further determine the TLC profile.RESULTS AND DISCUSSIONSMethyl benzoate, C6H8O2, is an aromatic hydrocarbon, a methyl ester with a dull appearance and used in perfumery. With Methyl benzoate, methyl m-nitrobenzoate will be synthesized and will further be purified by re-crystallization (2) with results shown in gameboard 1.Table 1. Percentage Yield of methyl m-nitrobenzoate plenty of conical flask91.749 gMass of methyl benzoate and conical flask92.109 gMass of methyl benzoate0.360 gMass of re-crystallized methyl m-nitrobenzoate0.257 g% yieldThe mass of methyl benzoate was determined by remainder then cooled in an ice bath then added conc. H2SO 4. The solution will still be colorless because methyl benzoate is soluble in H2SO4. Thus, it will form a undiversified mixture. On the contrary, it will form a yellow solution if the flask used is contaminated. The nitrating agent prepared in an ice bath because nitration is an exoergic that requires save 15C and must not increase (1). HNO3 and H2SO4 should be added in the homogenous solution slowly while stirring to annul side products formation like compounds with o- and p- orientation. Also, it will result to a low yield of the product in demand(p). Likewise, fast addition will result to get a high temperature that must be 15C only. adjunct of H2SO4 if cloudiness will occur is important since methyl benzoate is soluble in sulfuric acid and will produce a colorless solution.The mixture of HNO3 and H2SO4 produces nitronium ion that will attach to the benzene ring (5). Methyl Benzoate is characterized for being electron rich and thus sure-footed of reacting to electrophiles and undergoes EAS or Electrophilic Aromatic Substitution with a mechanism via carbocation C+ intermediate shown in Figure 1.Figure 1. Complete instrument of Nitration via Carbocation IntermediateIt follows 3 steps that started from the generation of electrophile which is the nitronium ion, NO2. Then, the formation of carbocation intermediate where nitronium ion will be attacked by the nucleophile will follow. The carbocation in the second step is capable of resonating since aromatic compounds are resonance structure wherein the electron pair can move around the molecule. The resonance of the benzene ring makes them stable and favorable to the reaction since the more stabilize the benzene ring is, the more reaction. The last step is the dissociation of H+ and the reformation of aromatic ring where the electrophile will substitute in one of the hydrogens on the benzene ring. This mechanism resulted to an overall reaction shown in Figure 2.Figure 1. Nitration of methyl benzoateThe so lvent of the nitration which is the sulfuric acid will protonate the reagent, methyl benzoate, which will create stabilized carbocation intermediate. The electrophile or the electron poor nitronium ion, will react to the protonated intermediate in the meta position. The carboxyl group belongs to the e- withdrawing group that deactivates the aromatic ring. Since electron withdrawing group has a meta orientation and a deactivator, the reaction will take place in the meta position. Likewise, the ortho and para positions are destabilized (5). The major product now is the methyl m-nitrobenzene which has nitro and carboxyl group being both electron withdrawing groups oriented at the meta position. aft(prenominal) adding the nitrating agent, the reaction mixture was added 10 g of crushed ice until it coagulated and filtrated by vacuum filtration to get a dryer product. It was then washed by cold distilled water and 5% NaHCO to make excess acid neutralize that made the product green-colore d. The product was dried over a steam bath and re-crystallized with methanol for purification. By washing the product with methanol, by-products or impurities like substitution on different places on the aromatic ring (ortho and para positions), methyl-2-nitrobenzoate or maybe methy-3-nitrobenzoate formed during the previous reactions should purified to get the favorite(a) product. However, the methanol is preferred cold to control loss of desired product. The re-crystallized methyl m-nitrobenzoate weighed 0.257 and had % yield. The melting point of the re-crystallized methyl m-nitrobenzoate was determined to be 74C that is close to its true melting point being 78C. The % difference was determined to be 5.13% as shown in Table 2.Table 2. break up point of re-crystallized methyl m-nitrobenzoateMelting point of re-crystallized methyl m-nitrobenzoate74CTrue Melting point of methyl m-nitrobenzoate78C% difference5.13%To see how much products were formed and to check its purity, the TL C profile or Thin Layer Chromatography should be done (6). Each trial as the TLC plate was dipped in the solvent (Ethyl acetate) should have only 1 spot that is equivalent to 1 compound. If 3 spots were formed in the TLC plate on 3 trials when the solvent moves on the top of the plate by capillary action, it simply means that 3 compounds were present in the product. Thus, making it considered as not pure. The spots will be clealy visualized when the plate is placed in an one vapor (4) here it sublimes from solid to liquid stain. Also, other compounds are capable of adsorbing iodine and become visible. On the contrary, the re-crystallized m-nitrobenzene formed had been considered as a pure compound as illustrated in Figure 3 and had an Rf value of 0.79.Rf = dspot / dsolvent frontRf = 3.75 cm / 4.6 cmCDocuments and SettingsnicolleMy DocumentsCollege Files2nd Year 2nd SemORGCHEMLABEXPT4 NITRATION OF METHYL BENZOATETLC Plate.jpgRf = 0.79dsolvent front = 4.7 cmdspot = 3.7 cmFigure 3. T LC ProfileThe desired product, methyl m-benzoate, purified by re-crystallization was successfully synthesized from methyl benzoate by avoiding the formation of other side-products. However, if phenyl benzoate was used, it will also follow EAS or Electrophilic Aromatic Substitution