Nitration of an Aromatic Ring - M-Nitrobenzoic Acid from Benzoic Acid
Essay by Archangel Nudalo • December 1, 2017 • Lab Report • 1,538 Words (7 Pages) • 1,703 Views
Essay Preview: Nitration of an Aromatic Ring - M-Nitrobenzoic Acid from Benzoic Acid
Exercise No. 11
Nitration of an Aromatic Ring
m-Nitrobenzoic Acid from Benzoic Acid
Archangel Gabriel J. Nudalo
Group No. 4
CHEM 40.1 12L
I. Introduction
Electrophilic aromatic substitution is a reaction used in many organic syntheses because it prohibits many functional groups from reacting to the aromatic ring. The general form for this reaction is:
Ar-H + E+ → Ar-E + H+
where Ar-H is an aromatic compound and E+ is an electrophile that can replace H from Ar-H.
In this exercise, nitric acid is protonated by sulfuric acid to form nitronium ion (NO2+). This ion functions as an electrophile and reacts with benzene to produce nitrobenzene and benzene-sulfuric acid (Laali & Gettwert, 2000). In chemical equation, it is shown as:
[pic 1]
(Image obtained from https://socratic.org)
Since COOH and NO2 are meta directors, they would always react in the 1,3- position of a benzene ring.
Other reactions that accompanies the formation of m-nitrobenzoic are:
- Dinitration to form 3,5-dinitrobenzoic acid
[pic 2]
Through the formula, the unfavourability of dinitration is seen since benzoic acid is more reactive than m-nitrobenzoic acid. In the formula, nitration is favored because NO2 is a stronger nucleophile than SO3.
- Sulfonation to form m-carboxybenzensulfonic acid
[pic 3]
In the formula, nitration is favored because NO2 is a stronger nucleophile than SO3.
Molecules like -OH and -NH2 donates electrons and are called activated substituents while -NO2 and -Cl withdraw electrons, therefore, they are called deactivating substituents (Carey, 2006).
II. Objectives
- To prepare an aromatic nitro compound by means of an EAS reaction
- To prepare m-nitrobenzoic acid from benzoic acid;
- To recrystallize the crude product; and
- To write the mechanism for the nitration of benzoic acid and the accompanying side reactions.
- To compare the starting material and the product.
- To differentiate between m-nitrobenzoic acid and benzoic acid by using chemical tests.
III. Materials and Methods
- Schematic Diagram of the Procedure
Part A. Synthesis and Isolation of m-Nitrobenzoic Acid
NOTE: CONDUCT SYNTHESIS IN THE FUMEHOOD![pic 4][pic 5][pic 6][pic 7][pic 8]
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Part B. Chemical test for the Comparison of Starting Material and Product
(For reaction with Bromine)[pic 34][pic 35][pic 36][pic 37][pic 38][pic 39][pic 40][pic 41]
(Place in “Halogenated Organic Wastes” after)
(For reaction Baeyer’s Test)
[pic 42][pic 43]
[pic 44]
(Place in “Mn-Containing Wastes” after)
(For Ferrous sulfate test)[pic 45]
[pic 46][pic 47]
[pic 48]
(Place in “Iron-Containing Wastes after”)
B. Setups
[pic 49]
Figure 1. Set-up for Suction Filtration
(*Image obtained from http://what-when-how.com/organic-chemistry
laboratory-survival-manual/recrystallization-part-1-laboratory-manual/)
[pic 50]
Figure 2. Set-up for Hot Gravity Filtration
(*Image obtained from https://www.emaze.com/@AQZFIWZI/filtration)
[pic 51]
Figure 3. Set-up for Melting Point Determination.
(*Image obtained from https://www.yaksic.com/ispp2.html)
C. List of Necessary Chemicals
Name and Structure of the compound | Function in the Exercise | Physical Properties | Hazards | Precautions |
m-Nitrobenzoic Acid | Final product | Solid, bitter, off-white in color, yellowish | Health Hazard Fire Hazard | Keep away from heat and sources of ignition. Use proper lab attire in handling. |
Benzoic Acid | Starting sample | Solid | Health Hazard Fire Hazard Flammability | Keep away from heat and sources of ignition. Use proper lab attire in handling. Seek medical advice if ingested. Avoid contact with skin and eyes. |
Nitric Acid | Reagent used in the synthesis of m-Nitrobenzoic acid | Acidic liquid, clear to light yellow in color | Health Hazard | Keep locked in a dry container. Keep away from heat, sources of ignition, and combustible material. Keep away from incompatibles such as reducing agents, combustible materials, organic materials, metals, etc. |
Sulfuric Acid | Reagent used in the synthesis of m-Nitrobenzoic acid | Thick oily odorless liquid with an acidic taste | Health Hazard Fire Hazard | Keep locked in a dry container. If ingested, seek medical advice immediately and show the container or the label. Keep away from incompatibles such as reducing agents, combustible materials, organic materials, metals, etc. |
Ethanol | To be mixed with KOH and to be used in the FeSO4 test | Colorless liquid that smells like wine or whiskey | Health Hazard Fire Hazard | Keep locked up and away from heat and sources of ignition. If ingested, seek medical advice immediately and show the container or the label. Avoid contact with skin and eyes. |
Potassium Hydroxide | To be mixed with C2H6O and to be used in the FeSO4 test | White odorless solid | Health Hazard Reactivity Personal Protection | Keep container dry. Do not ingest and breathe dust. In case of insufficient ventilation, wear suitable respiratory equipment. Avoid contact with skin and eyes. Keep away from incompatibles such as organic materials, metals, acids, moisture. |
Ferrous Sulfate | Reagent used in the comparison test | Grayish white to yellowish solid | Health Hazard Personal Protection | Do not breathe dust. In case of insufficient ventilation, wear suitable respiratory equipment. If you feel unwell, seek medical attention and show the label when possible. Avoid contact with skin and eyes. |
Bromine | Reagent used in the comparison test | Pungent red-brown liquid Soluble in diethyl ether, cold water, alcohol, chloroform, carbon disulfide, carbon tetrachloride, concentrated hydrochloric acid, and aqueous solution of bromides. | Health Hazard | Keep in a locked dry container. Do not ingest and breathe gas/fumes/ vapor/spray. In case of insufficient ventilation, wear suitable respiratory equipment. Keep away from incompatibles such as reducing agents, combustible materials, and organic materials. |
Potassium Permanganate | Reagent used in the comparison | Purple odorless solid with a sweetish taste | Health Hazard Personal Protection | Keep away from heat, sources of ignition, and from combustible material. Do not ingest and breathe dust. Avoid contact with skin and eyes. Keep away from incompatibles such as organic materials, metals, acids. |
*Data obtained from www.sciencelab.com
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