Electrophilic Aromatic Substitution Formal Lab
Electrophilic Aromatic Substitution
Objective
The objective of this experiment was to illustrate electrophilic aromatic substitution by synthesizing p-nitroanilide (as well as ortho) from acetanilide by nitration. The para form was separated from the ortho form based on solubility properties using recrystallization techniques.
Synthetic equations:
Physical Properties & Hazards of Reagents/Products: (all taken from Sigma-Aldrich website)
Acetanilide
MM = 135.16 g/mol
Melting point = 113-115°C
Hazards: acute toxicity
Sulfuric acid
MM = 98.08 g/mol
Boiling point = 290°C
Density = 1.840 g/mL
Hazards: corrosive to metals and skin, serious eye damage
Nitric acid
MM = 63.01 g/mol
Boiling point = 120.5°C
Density = 1.480 g/mL
Hazards: oxidizing liquid, corrosive to metals and skin, serious eye damage
Ethanol
MM = 46.07 g/mol
Boiling point = 78°C
Density = 0.789 g/mL
Hazards: flammable
p-nitroacetanilide
MM = 180.16 g/mol
Melting point = 215-217°C
Hazards: acute toxicity
o-nitroacetanilide
MM = 180.16 g/mol
Melting point = 92-94°C
Hazards: acute toxicity
Water
MM = 18.02 g/mol
Boiling point = 100°C
Density = 1.00 g/mL
Procedure
The nitrating agent was prepared by slowly adding cold concentrated sulfuric acid (1.7 mL, 0.0319 mol) to cold concentrated nitric acid (0.6 mL, 0.0141 mol) in a 50 mL Erlenmeyer flask. The mixture was carefully swirled in an ice bath to ensure that the two concentrated acids were thoroughly mixed together. In a second 50 mL Erlenmeyer flask, acetanilide (1.0 g, 0.0074 mol) was dissolved in concentrated sulfuric acid (1.5 mL, 0.0281 mol) by having the acid slowly added to the solid while the mixture was swirled. Heating with a hot plate was also required to dissolve the acetanilide. When all of the solid had dissolved, the flask was cooled in an ice bath. The cold nitrating agent was added drop-wise to the cold acetanilide mixture. The flask was swirled after each addition of the nitrating
Objective
The objective of this experiment was to illustrate electrophilic aromatic substitution by synthesizing p-nitroanilide (as well as ortho) from acetanilide by nitration. The para form was separated from the ortho form based on solubility properties using recrystallization techniques.
Synthetic equations:
Physical Properties & Hazards of Reagents/Products: (all taken from Sigma-Aldrich website)
Acetanilide
MM = 135.16 g/mol
Melting point = 113-115°C
Hazards: acute toxicity
Sulfuric acid
MM = 98.08 g/mol
Boiling point = 290°C
Density = 1.840 g/mL
Hazards: corrosive to metals and skin, serious eye damage
Nitric acid
MM = 63.01 g/mol
Boiling point = 120.5°C
Density = 1.480 g/mL
Hazards: oxidizing liquid, corrosive to metals and skin, serious eye damage
Ethanol
MM = 46.07 g/mol
Boiling point = 78°C
Density = 0.789 g/mL
Hazards: flammable
p-nitroacetanilide
MM = 180.16 g/mol
Melting point = 215-217°C
Hazards: acute toxicity
o-nitroacetanilide
MM = 180.16 g/mol
Melting point = 92-94°C
Hazards: acute toxicity
Water
MM = 18.02 g/mol
Boiling point = 100°C
Density = 1.00 g/mL
Procedure
The nitrating agent was prepared by slowly adding cold concentrated sulfuric acid (1.7 mL, 0.0319 mol) to cold concentrated nitric acid (0.6 mL, 0.0141 mol) in a 50 mL Erlenmeyer flask. The mixture was carefully swirled in an ice bath to ensure that the two concentrated acids were thoroughly mixed together. In a second 50 mL Erlenmeyer flask, acetanilide (1.0 g, 0.0074 mol) was dissolved in concentrated sulfuric acid (1.5 mL, 0.0281 mol) by having the acid slowly added to the solid while the mixture was swirled. Heating with a hot plate was also required to dissolve the acetanilide. When all of the solid had dissolved, the flask was cooled in an ice bath. The cold nitrating agent was added drop-wise to the cold acetanilide mixture. The flask was swirled after each addition of the nitrating
References: 1) Sigma-Aldrich website