Friedel Crafts Alkylation
Carly Bolyard
Chem 2020
Experiment Performed:
9/17/2014-9/24/2014
Lab Partner: Erika Breeden
Synthesis of 1,4-Di-t-Buytl-2,5-Dimethoxybenzene via Friedel-Crafts Alkylation
Title: Synthesis of 1,4-Di-t-buytl-2,5-dimethoxybenzene via Friedel-Crafts Alkylation Introduction: Friedel-Crafts alkylation of benzene (and substituted benzenes) involves substituting a hydrogen atom on a benzene ring with an alkyl group. In the reaction a new alkyl group becomes bonded to a carbon atom of the aromatic ring which occurs by treatment of benzene (or substituted benzene) with a stable carbocation. The purpose of this experiment is to synthesize 1, 4-Di-t-butyl-2, 5 – dimethoxybenzene via the Friedel-Crafts alkylation mechanism by reacting 1, 4 – dimethoxybenzene with tertiary-butyl alcohol in the presence of sulfuric acid as a Lewis acid catalyst, and involves the attack of the aryl group at the electrophilic trimethylcarbocation. The resulting product will be recrystallized using methanol and characterized using TLC and melting point analysis.
Materials:
400-mL beaker, ice for ice bath, 25 mL Erlenmeyer flask, several volumetric and Pasteur pipets, 1.0-mL 10 x 100 mm reaction tube, glass stirring rod, rubber bulb, TLC plate
Table 1. Chemicals used in Friedel Crafts synthesis of 1,4-di-t-butyl-2,5-dimethoxybenzene
Substance
Molecular Weight (g/mol)
Amount Used
Moles Used
Mole Ratio
Melting Point (°C)
Boiling Point (°C)
Density (g/mL)
1,4-dimethoxybenzene
138.16
0.128g
9.26*10-4
1:1
58-60
N/A
1.053
Acetic Acid
60.0
~15 drops
N/A
N/A
N/A
118
1.049
t-butyl alcohol
74.12
0.200mL
2.12*10-3
2:1
N/A
83
0.7856
H2SO4
98.06
~15drops
N/A
N/A
N/A
327
1.84
Methanol
32.0
~6mL
N/A
N/A
N/A
64.7
0.7914
Water
18.0
5mL
N/A
N/A
0
100
1.0
1,4-Di-t-butyl-2,5-dimethoxybenzene
250.17
product product 1:1
102-105
N/A
N/A
Reaction and its Mechanism:
The limiting reagent for this reaction is 1, 4 – dimethoxybenzene. See calculations section for explanation.
Overall Reaction: C8H10O2+
Chem 2020
Experiment Performed:
9/17/2014-9/24/2014
Lab Partner: Erika Breeden
Synthesis of 1,4-Di-t-Buytl-2,5-Dimethoxybenzene via Friedel-Crafts Alkylation
Title: Synthesis of 1,4-Di-t-buytl-2,5-dimethoxybenzene via Friedel-Crafts Alkylation Introduction: Friedel-Crafts alkylation of benzene (and substituted benzenes) involves substituting a hydrogen atom on a benzene ring with an alkyl group. In the reaction a new alkyl group becomes bonded to a carbon atom of the aromatic ring which occurs by treatment of benzene (or substituted benzene) with a stable carbocation. The purpose of this experiment is to synthesize 1, 4-Di-t-butyl-2, 5 – dimethoxybenzene via the Friedel-Crafts alkylation mechanism by reacting 1, 4 – dimethoxybenzene with tertiary-butyl alcohol in the presence of sulfuric acid as a Lewis acid catalyst, and involves the attack of the aryl group at the electrophilic trimethylcarbocation. The resulting product will be recrystallized using methanol and characterized using TLC and melting point analysis.
Materials:
400-mL beaker, ice for ice bath, 25 mL Erlenmeyer flask, several volumetric and Pasteur pipets, 1.0-mL 10 x 100 mm reaction tube, glass stirring rod, rubber bulb, TLC plate
Table 1. Chemicals used in Friedel Crafts synthesis of 1,4-di-t-butyl-2,5-dimethoxybenzene
Substance
Molecular Weight (g/mol)
Amount Used
Moles Used
Mole Ratio
Melting Point (°C)
Boiling Point (°C)
Density (g/mL)
1,4-dimethoxybenzene
138.16
0.128g
9.26*10-4
1:1
58-60
N/A
1.053
Acetic Acid
60.0
~15 drops
N/A
N/A
N/A
118
1.049
t-butyl alcohol
74.12
0.200mL
2.12*10-3
2:1
N/A
83
0.7856
H2SO4
98.06
~15drops
N/A
N/A
N/A
327
1.84
Methanol
32.0
~6mL
N/A
N/A
N/A
64.7
0.7914
Water
18.0
5mL
N/A
N/A
0
100
1.0
1,4-Di-t-butyl-2,5-dimethoxybenzene
250.17
product product 1:1
102-105
N/A
N/A
Reaction and its Mechanism:
The limiting reagent for this reaction is 1, 4 – dimethoxybenzene. See calculations section for explanation.
Overall Reaction: C8H10O2+