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CHM 1321 Lecture Notes - Lecture 6: Electrophilic Aromatic Substitution, Acetanilide, Nitronium Ion

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13 Feb 2018

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University of Ottawa

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Francis Loiseau

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CHM 1321 Full Course Notes

CHM 1321 Full Course Notes

Document Summary

The purpose of this lab was the nitration of acetanilide demonstrating regioselectivity in electophilic aromatic substitution. In the first part of the lab, a nitronium ion is produced from the reaction of sulphuric acid and nitric acid, where sulphuric acid, the stronger acid, donates a proton, forming a molecule of water. The nitronium ion is a strong electrophile and in the second part it reacts with acetanilide to produce a nitro acetanilide, in an electrophilic aromatic substitution (eas). There are three possible isomers that the electrophilic substitution can produce; para, where the no2 is on carbon 4, ortho, where it"s on carbon 2, and meta, carbon 3. This shows the possible products, para is the major product produced due to resonance stabilization as the charge can be delocalized over many atoms, and so the carbocation intermediate is the most stable. Ortho is favored less than para because of sterics from the acetanilide functional group.

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Related Questions

please help calculate percent yield

data:
step 2= .0906g
step 3= .101g
step 5= .1986g
step 7= .2105g
final product weight is= .0971g

I've already subtracted the weight of the vials so that only the weight of the compounds are shown

Please help me answer the following questions from thepicture:

b) Draw the major products for this reaction

C) Draw the major products

Questions: 3,4,13

Write a formal procedure about the expiremnt ( please note where the procedure is starting just write it)

-SYNTHESIS OF A DYE, METHYL ORANGE is the electrophile. Therefore the same rules as for any electrophilic aromatic substitution ap- ply: electron donating groups such as amines, ethers and alkyl groups activate the aromatic contact with the skin should be avoided substrate and are ortho-para directors, hlAvoid breathing the fumes. As a general rule groups such as carboxylic esters and nitro all aromatic amines should be considered as Safety Considerations N.N-Dimethylaniline is quite toxic. Any groups are deactivators and meta directors The first step in an azo coupling is the forma Normal precautions apply to the use of concentrated acids. on of the diazonium ion intermediate, which is formed by reaction of an aromatic amine with nitrous acid. This process is called diazotation. Sodium dithionite slowly decomposes in water Nitrous acid is sodium nitrite and hydrochloric acid. For the rotten egg smell). Some people with asthma reaction in this experiment, the diazoniu of sulfanilic acid has to be formed. However sulfanilic formed in situ by reaction of and forms H,S, which really smells bad (the m ion might be highly sensitive to these chemicals. acid is not soluble in acidic solution, and the medium in this reaction has to be acidic to form the nitrous acid. This problem is circum- vented by dissolving the sulfanilic acid first in alkaline solution by addition of sodium carbon ate. At the beginning of the reaction, when HCI is added, two things will happen: nitrous acid Procedure In a small Erlenmeyer flask, dissolve 0.06 g of sodium carbonate in about S mL of water. Add 0.2 g of sulfanilic acid monohydrate and heat to reflux until it is homogeneous. Cool to room formed in situ and the sulfanilic acid will temperature and add 0.08 g of sodium nitrite and stir until homogeneous. Cool in an ice water bath for 5-10 minutes until the temperature is below 10 Â°C. Add 0.25 mL concentrated hy precipitate out as a very finely divided precipi tate, which is highly reactive. The diazonium salt of the sulfanilic acid will be formed, which is also insoluble in the reaction medium, but drogen chloride to the solution. The diazoniu again very finely divided. The diazonium ion salt should precipitate as a finely divided whi will react immediately with the highly reactive bresipitate, Keep this solution cold N,N-dimethylaniline to form methyl orange Methyl orange is an acid base indicator: At In a vial or flask, mix 0.14 mL. of N,N-dlimethyl pH > 4.4, methyl orange exists mostly as the aniline with 0.10 ml. of glacial acetic acid. Add yellow negative sulfonate ion, while at pH