Benzene Side Chain Reactions
TLDRThis video script delves into the fascinating side chain reactions of benzene, detailing its bromination to form bromobenzene, followed by reactions with dimethyl copper lithium to produce toluene and NBS to yield benzyl bromide. It further explores the synthesis of benzaldehyde through oxidation and the Gadem in Coach reaction, as well as the formation of benzyl amine and benzonitrile. The Friedel-Crafts alkylation and subsequent reactions to create styrene and benzoic acid are also covered, alongside the oxidation of alkyl groups and the reduction of nitrobenzene to aniline, concluding with the formation of an amide from aniline and acid chloride.
Takeaways
- 🌟 Benzene can undergo bromination to form bromobenzene using Br2 and FeBr3 as a catalyst.
- 🔄 Bromobenzene reacts with dimethyl copper lithium to form toluene through a methyl group displacement.
- 🌞 NBS can be used to replace a benzylic hydrogen with a bromine atom, resulting in benzyl bromide.
- 🍷 Benzyl bromide can be converted to benzyl alcohol via an SN2 reaction with a hydroxide ion.
- 🧪 Benzyl alcohol can be further oxidized to benzaldehyde using PCC.
- 🔬 An alternative method to produce benzaldehyde involves reacting benzene with carbon monoxide, hydrochloric acid, aluminum chloride, and copper chloride.
- 🌐 Benzyl bromide reacts with ammonia in an SN2 reaction to form a protonated amine, which can be deprotonated to form benzyl amine.
- 💥 Benzyl bromide can also react with cyanide to form a nitro compound, which can be reduced to a primary amine with an additional carbon.
- 🔨 Friedel-Crafts alkylation can add an ethyl group to benzene to form ethylbenzene, which can be further brominated with NBS.
- 🔄 Using a strong base like tert-butoxide on benzyl bromide can lead to an E2 reaction, resulting in the formation of styrene.
- 🍂 Oxidation of toluene with a strong oxidizing agent like potassium permanganate can convert the methyl group to a carboxylic acid, forming benzoic acid.
- 🌿 Multiple alkyl groups on a benzene ring can be selectively oxidized to carboxylic acids using chromic acid or potassium permanganate, except for the tert-butyl group due to the lack of benzylic hydrogens.
- ⚔️ Nitrobenzene can be reduced to aniline using metals like iron, zinc, or tin in the presence of hydrochloric acid.
- 🧩 Aniline can react with acid chlorides to form an amide functional group.
Q & A
What is the first reaction described in the video script involving benzene?
-The first reaction described is the bromination of benzene, where benzene reacts with bromine (Br2) and iron tribromide (FeBr3) as a catalyst, resulting in the substitution of a hydrogen atom with a bromine atom to form bromobenzene.
What is the product formed when bromobenzene reacts with dimethyl copper lithium?
-The reaction of bromobenzene with dimethyl copper lithium results in the displacement of the bromine atom by a methyl group, producing toluene as the product.
What does NBS stand for and what reaction does it facilitate?
-NBS stands for N-Bromosuccinimide. It is used to replace a benzylic hydrogen with a bromine atom, forming benzyl bromide.
How can benzyl alcohol be synthesized from benzyl bromide?
-Benzyl bromide can undergo an SN2 reaction with a nucleophile, such as a hydroxide ion, which attacks the carbon, expelling the bromine as the leaving group, to yield benzyl alcohol.
What reagent is used to oxidize benzyl alcohol to benzaldehyde?
-PCC (Pyridinium chlorochromate) is used to oxidize the primary alcohol of benzyl alcohol into an aldehyde, resulting in benzaldehyde.
What is an alternative method to produce benzaldehyde from benzene?
-An alternative method involves reacting benzene with carbon monoxide, hydrochloric acid, aluminum chloride, and copper chloride, which also yields benzaldehyde.
What happens when benzyl bromide reacts with ammonia?
-Benzyl bromide reacts with ammonia in an SN2 reaction, resulting in the formation of a protonated amine, which is then deprotonated to form benzyl amine.
How can benzyl bromide be converted to a nitro compound?
-Benzyl bromide can react with the nucleophile cyanide, which attacks the carbon and displaces the bromine atom, resulting in the formation of a nitro group on the carbon adjacent to the benzene ring.
What is the product of reducing a nitro group attached to a carbon next to the benzene ring?
-Reducing a nitro group with hydrogen gas converts it into a primary amine, but with an additional carbon, resulting in an amine between the NH2 and the benzene ring.
How can the Friedel-Crafts alkylation reaction be used to add a carbon atom to benzene?
-The Friedel-Crafts alkylation reaction involves reacting benzene with an alkyl halide, such as ethyl chloride, in the presence of an aluminum chloride catalyst to add an ethyl group to the benzene ring, forming ethylbenzene.
What is the final product of the reaction sequence starting from benzene and involving bromination, Friedel-Crafts alkylation, and oxidation?
-Starting from benzene, bromination leads to bromobenzene, Friedel-Crafts alkylation with methyl chloride forms toluene, and oxidation with a strong oxidizing agent like potassium permanganate results in benzoic acid.
What happens when a compound with multiple alkyl groups on a benzene ring is oxidized with chromic acid?
-Upon oxidation with chromic acid, methyl, ethyl, and isopropyl groups attached to the benzene ring are oxidized to their corresponding carboxylic acids, while the tert-butyl group, being on a quaternary carbon without benzylic hydrogen, is not oxidized to a carbonyl group.
What are the products of the reaction between benzene, nitric acid, and sulfuric acid?
-The reaction between benzene, nitric acid, and sulfuric acid results in the formation of nitrobenzene, with an NO2 group attached to the benzene ring.
How can aniline be produced from nitrobenzene?
-Nitrobenzene can be reduced using a metal such as iron in hydrochloric acid, zinc, or tin to convert the NO2 group to an NH2 group, yielding aniline.
What functional group is formed when aniline reacts with an acid chloride?
-The reaction of aniline with an acid chloride results in the formation of an amide functional group.
Outlines
🔬 Benzene Side Chain Reactions Overview
This paragraph introduces various side chain reactions of benzene, starting with the bromination of benzene using Br2 and FeBr3 to form bromobenzene. It then describes the reaction of bromobenzene with dimethyl copper lithium to produce toluene. Further reactions include the use of NBS to form benzyl bromide, and subsequent reactions to synthesize benzyl alcohol and benzaldehyde through SN2 reactions and oxidation with PCC. Additionally, the paragraph covers the Gadem in Coach reaction as an alternative method to produce benzaldehyde, and the reaction of benzyl bromide with ammonia to form a protonated amine, which can be deprotonated to yield benzyl amine. The paragraph concludes with the reaction of benzyl bromide with cyanide to introduce a nitro group, which can be reduced to a primary amine.
🌿 Friedel-Crafts Alkylation and Oxidation Reactions
The second paragraph delves into the Friedel-Crafts alkylation reaction to add ethyl groups to benzene, resulting in ethyl benzene, which can be further reacted with NBS to place a bromine atom on a benzylic carbon. The use of a strong base like tert-butoxide leads to an E2 reaction, forming styrene with a stable double bond. The paragraph also discusses the oxidation of toluene to benzoic acid using potassium permanganate and the selective oxidation of various alkyl groups attached to benzene rings with chromic acid, highlighting that tert-butyl groups cannot be oxidized to carbonyl groups due to the absence of benzylic hydrogens. Lastly, the paragraph touches on the nitration of benzene to form nitrobenzene and its reduction to aniline using metals like iron or zinc.
🧪 Advanced Benzene Derivatives Synthesis
The final paragraph briefly mentions the synthesis of an amide from aniline and an acid chloride, where the NH2 group of aniline reacts to form the desired amide functional group. This concise section suggests further complexity in benzene derivative chemistry beyond the scope of the initial reactions described.
Mindmap
Keywords
💡Benzene
💡Bromination
💡Catalyst
💡Toluene
💡NBS
💡SN2 Reaction
💡PCC
💡Gadman-Koch Reaction
💡Benzylamine
💡Styrene
💡Benzoic Acid
💡Oxidation
💡Aniline
💡Amide
Highlights
Introduction to side chain reactions of benzene.
Bromination of benzene using BR2 and iron bromide as a catalyst to form bromobenzene.
Reaction of bromobenzene with dimethyl copper lithium to produce toluene.
Use of NBS to create benzyl bromide by substituting a benzylic hydrogen.
SN2 reaction of benzyl bromide with hydroxide ion to form benzyl alcohol.
Oxidation of benzyl alcohol to benzaldehyde using PCC.
Alternative synthesis of benzaldehyde via the Gatterman-Koch reaction.
Reaction of benzene with ammonia and subsequent deprotonation to form benzyl amine.
Introduction of a nitro group to benzyl bromide using cyanide.
Reduction of the nitro group to a primary amine in the presence of hydrogen gas.
Conversion of the nitro group to a carbonyl group using H3O+.
Friedel-Crafts alkylation to add an ethyl group to benzene, forming ethylbenzene.
Introduction of a bromine atom to the benzylic carbon of ethylbenzene using NBS.
E2 reaction with tert-butoxide to form styrene.
Oxidation of toluene to benzoic acid using potassium permanganate.
Selective oxidation of alkyl groups on benzene rings with chromic acid.
Formation of nitrobenzene through the reaction of benzene with nitric and sulfuric acids.
Reduction of nitrobenzene to aniline using metal and acid.
Synthesis of an amide from aniline and acid chloride.
Transcripts
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