Results: Theoretical Yield: Methyl Benzoate: 0. The fourth region ranges from 1,500 to 400. Purification and analysis Methyl 3-nitrobenzoate is insoluble in water but soluble in hot ethanol. Secretary of Commerce on behalf of the U. Wash the crude product with a little ice-cold water. By the concept of resonance, we can label alternately electron-rich and electron-poor carbon atoms around the ring. Interpretation of data and conclusion.
Indicate the product formed on nitration of each of the following compounds: benzene, toluene, chlorobenzene, and benzoic acid. The X-axis provides the absorption number. Write equations for side reactions and explain how side products were removed from the product. Below each reactant, list the molecular weight, and amount used in grams or mLs and moles. Mechanism of the reactions showing the structures of intermediates and arrows to demonstrate electron movement 4.
A benzene ring peak at 1615. Melting Point C Mass g Pure methyl 77. . An infrared spectrum of the product was obtained and confirmed it is methyl m-nitrobenzoate. Since the meta positions are electron-rich, the nitronium group should seek to bond to that position, which is consistent with observation.
Weight of final product will be compared to crude weight to determine effectiveness of procedure. Because the amine group bears an element that releases electrons to the ring, the electron distribution around the ring shifts. For this reaction, the physical properties of interest are as follows: Methyl m-Nitrobenzoate can also be produced using other techniques. Aniline affords mostly 0- and p- isomers on bromination but gives mostly m-nitroaniline on nitration. You can change your mind and change your consent choices at anytime by returning to this site. Products Percent Yield Methyl m-nitrobenzoate 36% Table 2: Percent yield is represented by the actual yield over theoretical yield and multiplied by 100.
Why does the amount of the dinitration increase at high temperatures? Ice added will be minimal because excess retards nitration by interfering with the nitric acid-sulfuric acid equilibria. Lesson organisation To synthesise and recrystallize a sample of methyl 3-nitrobenzoate will take about 1½ h. The result is that the two adjacent carbons to the location of the substituent become more positively charged than in a normal aromatic ring. Each bond type absorbs energy of a specific frequency. The low percent yield was a chemical error. Meta-nitromethyl benzoate is the major product for the outlined mechanism due to the substituent attached to the aromatic ring in methyl benzoate. The carbonyl group withdraws electron density from the ring deactivating it towards electrophilic substitution.
Secretary of Commerce on behalf of the U. The resulting carbocation is unstable compared to the favored electron distribution of the aromatic ring structure; therefore, a hydrogen ion is withdrawn from the ring to neutralize the charge generated by the formation of the nitronium ion. The answer to this question lies in the nature of the substituents to be attached to the aromatic ring, the behavior of the amine group, and the concept of resonance. One problem experienced during the procedure was the unexpectedly rapid rise and fall of temperature perceived during the addition of the sulfuric and nitric acid solution. Theoretical yield of methyl m-nitrobenzoate: 0. Stir the crushed ice throughout. References Go To: , , Data compilation by the U.
If the nitronium group where to bond in any other position than the meta position, the intermediate would contain resonance forms where the resultant positive charge lies on the carbon of the ring bearing the original substituent. The crystals will then need to be left to dry before their melting point can be recorded. The overall yield of 73. This is the nitrating mixture. Summary In this experiment, you will synthesize methyl- m-nitrobenzoate from methyl benzoate via electrophilic aromatic substitution. Separately, prepare a mixture of 5.
The experiment resulted in 2. A strongly charged electrophile, in this case a nitro group, replaces a proton on the aromatic ring. Teaching notes The nitration of methyl benzoate is an example of electrophilic substitution. The reaction is regioselective and produces predominantly methyl 3-nitrobenzoate. In bromination, an element that can donate electrons is being added. While this reaction is a possible alternative, the rate of the reaction may be too slow to be practical due to the extremely strong deactivating nature of a nitronium group on the aromatic ring.
Experimental yield and percent yield show calculations 5. Below each product, list the theoretical yield in grams and moles 3. Select a region with no data or click the mouse on the plot to revert to the orginal display. In the case of the nitronium group, the substituent to be added bears a positive charge; therefore, it seeks electrons. In trying to agitate the mixture, monitor the temperature, and add the acid mixture to the reaction vessel, many mistakes in handling could have been made that result in spilled contents or contaminated reactions. Reference to the procedure with changes noted 2. The isolated product will be purified by recrystallization, and purity will be determined from the melting point.