Nitration Of Methyl Benzoate Mechanism

Introduction

Background

The purpose of this reaction it'due south to perform a nitration reaction on methyl benzoate to create a product of iii-nitro methyl benzoate. Within a nitration reaction information technology is typical to encounter electrophilic aromatic substitution reactions occur.¹ It is of import to notation the characteristics of an aromatic structure. for a chemical compound to be effluvious the molecule must be cyclic, planar, an effluvious band may only incorporate sp² hybridized atoms, and the number of π electrons in the delocalized π system must equal 4n + 2. This is besides known as the Huckel rule. This is normally used in organic chemistry.² With this criteria Benzene fits the description perfectly for aromaticity.

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With conveying out the reaction stated above, the electrophile within the methyl benzoate is the nitronium ion generated from the interaction of concentrated nitric and sulfuric acrid. This nitronium ion reacts with the protonated intermediate of the meta position. The meta position is where the electron density is at its highest point. This means that there is no positively charged resonance grade and will yield the intermediate arenium ion, which has four resonance forms. A proton is transferred from this ion to the basic bisulfate ion to give methyl 3-nitrobenzoate.¹To empathize the meta position that this reaction favors one must sympathize the departure of ortho, para in comparing to meta. These directors correlate with activating and deactivation groups. Both corresponding to hydrogen, activating groups increment the rate of electrophilic aromatic substitutions in comparing to deactivating groups where they decrease the charge per unit of electrophilic effluvious substitution. To further ones understanding of ortho, para, and meta directors, it is important to empathize the stability of the carbocation intermediate.³ This too explains why an ester group is a meta director instead of an ortho or para production.

Mechanism

Figure 1: Reaction Mechanism – Nitration of Methyl Benzoate

Side Reaction(s)

Figure 2: Possible Side Reaction

Experimental Department

Medium Size Examination Tube

0.6mL Conc. H2SO4

0.3g Methyl Benzoate

Swirl Mixture

Cool to 0°C

Prep mixture (0.2mL Conc. H2SO4 and 0.2mL Conc. HNO3)

Dropwise while stirring – Keep reaction at 0°C

Stir mixture for 25 minutes

Reaction Mixture at Room Temperature

Remove mixture from ice and warm to room temp for 15 minutes

Add 3g of cracked ice to 50mL beaker (cascade reaction mixture over ice)

Product should solidify

Vacuum filtration, wash with cold H2O and 0.5mL ice cold MeOH

Crude Product Recrystallization

Weigh production transfer to clean test tube

Recrystallization with equal weight of MeOH

Big quaintly of MeOH [sol.] and add H2O [insol.] dropwise

Mix solution with pipet to become clear

Remove sample from exam tube and filter product

Analysis

Obtain Mass

Calculate Percent Yield

Make up one's mind Melting Signal

Obtain H NMR

Table of Chemicals

Methyl Benzoate (C_eightH_eightO₂)

Concrete Properties: Colorless oily liquid

Chemical Backdrop: Humid Indicate 199°C, Melting Indicate -12°C, Molecular Weight 136.15g/mol

Hazards and Toxicity: Potential Acute Health Furnishings and Chronic Health Furnishings including, but not limited to, irritant in case of peel contact, heart contact and inhalation.⁴

Nitric Acid (HNO₃)

Concrete Properties: Liquid, Colorless, Yellow

Chemic Properties: Boiling Point 121°C, Melting Point -44°C, Molecular Weight 63.0g/mol

Hazards and Toxicity: Potential Acute Health Furnishings and Chronic Wellness Effects including, simply not limited to, irritant in instance of skin contact, eye contact and inhalation. Compound is an oxidizer.^five

Sulfuric Acrid (H₂And so₄)

Physical Properties: Colorless, Oily Liquid

Chemic Properties: Boiling Point 337°C, Melting Signal 10°C, Molecular Weight 98.0g/mol

Hazards and Toxicity: Potential Acute Health Effects and Chronic Health Effects including, merely not limited to, irritant in case of pare contact, heart contact and inhalation. Compound is corrosive.⁶

Nitrogen Dioxide (NO₂)

Physical Properties: Reddish-brownish gas or liquid

Chemic Properties: Humid Point 21.ane°C, Melting Point -11.2°C, Molecular Weight 46.0g/mol

Hazards and Toxicity: Potential Astute Health Effects and Chronic Health Effects including, but not limited to, irritant in case of pare contact, eye contact and inhalation. Chemical compound is corrosive, compressed gas, oxidizer, and astute toxicity.^seven

Results

Appearance and Colour of Product	White, Flaky, Solid Crystal
Melting Point Obtained	76°C
Mass of Crystals	0.248g
Per centum Yield	$57.54\%$
Overall Reaction Rate	Fast

Table1: Reaction Results

Limiting Reagent

$0.3\mathit{ml\; C}8H\mathrm{eight}O\mathrm{ii}\mathit{ x}\frac{1.08\frac{\mathrm{1000}}{\mathit{ml}}\mathit{ C}\mathrm{eight}H8O\mathrm{two}}{\mathrm{i}\mathit{ml \; C}8H8O\mathrm{ii}}\mathrm{ten}\frac{\mathrm{one}\mathit{mol \; C}8H8O2}{136\frac{\mathrm{one\; thousand}}{\mathit{mol}}\mathit{ C}8H8O2\mathit{}}x\frac{\mathrm{i}\mathit{mol\; C}\mathrm{viii}H7\mathit{NO}4}{1\mathit{mol \; C}\mathrm{viii}H\mathrm{eight}O2}=0.002238\mathit{ mol\; C}8H7\mathit{NO}4$

$0.2\mathit{ml\; HNO}\mathrm{three}\mathit{ x}\frac{\mathrm{one}\mathit{mol\; HNO}3}{63\frac{g}{\mathit{mol}}\mathit{ HNO}\mathrm{three}}\mathit{ x}\frac{1\mathit{mol \; C}\mathrm{eight}H7\mathit{NO}4}{\mathrm{one}\mathit{mol\; HNO}3}=0.00479\mathit{ mol\; C}8H7\mathit{NO}\mathrm{four}$

The limiting reagent is C₈H_eightO₂

Theoretical Yield and Pct Yield

$\frac{\mathit{Bodily\; Yield}}{\mathit{Theorectial\; Yield}}\mathit{ x}100=\frac{0.248\mathit{g\; C}8H\mathrm{vii}\mathit{NO}4}{0.431\mathit{ one\; thousand\; C}\mathrm{viii}H7\mathit{NO}\mathrm{iv}}\mathit{ ten}100=57.54\%$

H NMR

Effigy 3: H NMR Results

Discussion

In comparison of the obtained results and the literature values of 3-nitromethyl benzoate one may exist concerned that the final product was non obtained. The melting point of 3-nitromethyl benzoate is 78°C. The obtained melting betoken was 76°C. The percentage yield is relatively low at 57%. This is not a main business organisation due to it not falling below fifty%. The chief concern with the results is the H NMR results due to the obtained peaks in comparing to the literature. The spectra provided in the lab transmission is slightly different. The peaks are in the proper ppm areas but there are more than peaks than anticipated. this could exist due to an unlikely side reaction with an additional Nitro group added on the benzene ring. It is possible that the product obtained was non the expected product. To ostend that the construction of the final production is not of three-nitromethyl benzoate a C NMR should have been obtained. This was not completed due to the amount of time a C NMR takes, which is approximately 2 hours. overall, the production obtain may in fact be of 3-nitromethyl benzoate with a mixture of side part.

Conclusion

The data revealed from the data can explain the process of a nitration of methyl benzoate in an electrophilic effluvious substitution reaction. This reaction is very common in organic chemical science labs due to the importance of understanding ortho, para, and meta positions. It is also important with understanding electron density an intermediate form within resonance forms. Overall, the lab achieved what it was gear up out to do fifty-fifty if the side reaction occurred ane can understand why it occurred. From this experiment I learned how a nitration reaction occurs and the importance of learning how ortho, para and meta positions occur in a reaction. In add-on to learning the reaction practice with spectroscopy is very of import moving forward an organic chemistry.

References

1. Weldegirma, S.Experimental Organic Chemical science, 8th ed.; ProCopy: Tampa, FL, 2018.
2. Aromatic Compound. https://www.sciencedirect.com/topics/chemical science/aromatic-compound (accessed October 12, 2019).
3. Matthew; James; Lima, P.; Laura; Ashenhurst, J.; Haroon; Veekshith; Shrestha, Chiliad.; Parth; Nicole; Bandara, A.; Parvati; Emmy. Ortho-, Para- and Meta- Directors in Electrophilic Aromatic Exchange. https://world wide web.masterorganicchemistry.com/2018/01/29/ortho-para-and-meta-directors-in-electrophilic-aromatic-substitution/ (accessed Oct 12, 2019).
4. Methyl benzoate. https://pubchem.ncbi.nlm.nih.gov/compound/Methyl-benzoate (accessed October 12, 2019).
5. Nitric acid. https://pubchem.ncbi.nlm.nih.gov/compound/944 (accessed Oct 12, 2019).
6. Sulfuric acrid. https://pubchem.ncbi.nlm.nih.gov/compound/1118 (accessed Oct 12, 2019).

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Nitration Of Methyl Benzoate Mechanism,

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