Organic Chemistry: Alkenes and Alkynes Reaction
11 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the chemical name for the reaction of alkenes with potassium permanganate?

Oxidation

What is the product formed when alkynes are oxidized by potassium permanganate?

  • Geminal diketones (correct)
  • Geminal diols
  • Alkene
  • Alkane

The reaction between alkenes and potassium permanganate is fast.

False (B)

Why does potassium permanganate react with alkenes and alkynes, but not with alkanes and aromatic rings?

<p>Alkenes and alkynes have double and triple bonds, respectively, which can be oxidized by potassium permanganate. Alkanes and aromatic rings have only single bonds, which are more stable and less susceptible to oxidation.</p> Signup and view all the answers

What color is the precipitate of manganese oxide formed during the reaction of potassium permanganate with alkenes and alkynes?

<p>Brown (A)</p> Signup and view all the answers

What is the primary reason for the slow reaction rate between potassium permanganate and hydrocarbons?

<p>The reaction is slow due to the fact that potassium permanganate is not soluble in hydrocarbons. The reaction occurs at the interface between the two phases, which limits the rate at which the reactants can come into contact.</p> Signup and view all the answers

What is the difference between a geminal diol and a geminal diketone?

<p>A geminal diol has two hydroxyl (OH) groups attached to the same carbon atom, while a geminal diketone has two carbonyl (C=O) groups attached to the same carbon atom.</p> Signup and view all the answers

Geminal diols and diketones can be further oxidized by permanganates under harsh conditions to form manganese dioxide.

<p>True (A)</p> Signup and view all the answers

What is the purpose of using different hydrocarbons in the procedure described?

<p>The purpose is to demonstrate the selectivity of potassium permanganate, which reacts with compounds containing multiple bonds (alkenes, alkynes) but not with saturated hydrocarbons (alkanes) or aromatic rings.</p> Signup and view all the answers

Describe the observation that indicates a positive reaction between potassium permanganate and a hydrocarbon.

<p>A positive reaction is indicated by the formation of a brown precipitate, which corresponds to manganese dioxide, at the interface between the hydrocarbon and the permanganate solution.</p> Signup and view all the answers

In the procedure, why does the permanganate solution remain purple when hexane and toluene are used?

<p>Hexane and toluene do not react with potassium permanganate. (C)</p> Signup and view all the answers

Flashcards

Potassium Permanganate Oxidation of Alkenes

A chemical reaction where alkenes are oxidized to geminal diols, forming a brown precipitate of manganese dioxide.

Geminal Diols

Two hydroxyl (-OH) groups attached to adjacent carbon atoms.

Potassium Permanganate Oxidation of Alkynes

A chemical reaction where alkynes are oxidized to geminal diketones, forming a brown precipitate of manganese dioxide.

Geminal Diketones

Two carbonyl (C=O) groups attached to adjacent carbon atoms.

Signup and view all the flashcards

Interface

The junction between two immiscible liquids, like water and a hydrocarbon.

Signup and view all the flashcards

Manganese Dioxide Formation

The reduction of purple potassium permanganate (KMnO4) to form brown manganese dioxide (MnO2) during oxidation reactions.

Signup and view all the flashcards

Oxidation at the Interface

A chemical reaction that occurs at the interface between water and hydrocarbons because neither water nor potassium permanganate is soluble in hydrocarbons.

Signup and view all the flashcards

Slow Reaction

A slow chemical reaction that requires several minutes to complete.

Signup and view all the flashcards

Hexane

A colorless, highly flammable liquid alkane.

Signup and view all the flashcards

Cyclohexene

A colorless, flammable, cyclic alkene.

Signup and view all the flashcards

1-Hexyne

A colorless, flammable alkyne with a triple bond.

Signup and view all the flashcards

Toluene

A colorless, flammable aromatic hydrocarbon with a benzene ring.

Signup and view all the flashcards

Aqueous Potassium Permanganate

A purple aqueous solution used to oxidize alkenes and alkynes.

Signup and view all the flashcards

Negative Test

A negative test result for the reaction with potassium permanganate, where the solution remains purple.

Signup and view all the flashcards

Positive Test

A positive test result for the reaction with potassium permanganate, where a brown precipitate forms.

Signup and view all the flashcards

No Reaction

The absence of a reaction between a hydrocarbon and potassium permanganate.

Signup and view all the flashcards

Partial Solubility

The limited solubility of cyclohexene and 1-hexyne in potassium permanganate solution.

Signup and view all the flashcards

Interface Reaction

The interaction between potassium permanganate and a hydrocarbon at the liquid interface.

Signup and view all the flashcards

Manganese Dioxide Formation After 5 Minutes

The formation of brown manganese dioxide precipitate after 5 minutes of mixing a hydrocarbon with potassium permanganate.

Signup and view all the flashcards

Further Oxidation

The process of adding more oxidizing power to convert a geminal diol or a geminal diketone to a different product.

Signup and view all the flashcards

Inertness to Oxidation

The chemical resistance of alkanes and aromatic rings to potassium permanganate oxidation under mild conditions.

Signup and view all the flashcards

Mixing Hydrocarbons and Potassium Permanganate

The process of mixing a hydrocarbon with potassium permanganate solution.

Signup and view all the flashcards

Purple Solution for Hexane and Toluene

The observation of a purple solution for hexane and toluene after mixing with potassium permanganate.

Signup and view all the flashcards

Partial Solubility for Cyclohexene and 1-Hexyne

The observation of partial solubility between cyclohexene and 1-hexyne with potassium permanganate.

Signup and view all the flashcards

Brown Precipitate Formation for Cyclohexene and 1-Hexyne

The observation of a brown precipitate forming in the test tubes containing cyclohexene and 1-hexyne after 5 minutes of mixing with potassium permanganate.

Signup and view all the flashcards

Brown Precipitate as Positive Result

The presence of a brown precipitate indicates a positive result

Signup and view all the flashcards

Absence of Brown Precipitate as Negative Result

The absence of a brown precipitate indicates a negative result

Signup and view all the flashcards

Distinguishing Hydrocarbons

The reaction with potassium permanganate is used to distinguish between different types of hydrocarbons.

Signup and view all the flashcards

Study Notes

Reaction with Potassium Permanganate

  • Alkenes can be oxidized to geminal diols using dilute aqueous potassium permanganate. Geminal diols have two hydroxyl groups on adjacent carbon atoms.
  • Alkynes can be oxidized to geminal diketones using the same method.
  • The reaction produces a brown precipitate of manganese dioxide (MnO2).
  • This reaction happens at the interface between the water and hydrocarbon solutions as neither substance is soluble in the other.
  • Reaction time is slow, requiring several minutes for the brown precipitate to form.
  • Example: The oxidation of 3-hexene to 3,4-hexanediol occurs with the consumption of purple potassium permanganate. This is followed by the formation of a brown precipitate of manganese dioxide
  • Example: The oxidation of 3-hexyne to 3,4-hexanedione involves a similar process.

Procedure

  • Use four test tubes labeled for different hydrocarbons (hexane, cyclohexene, 1-hexyne, and toluene).
  • Add 10 drops of each hydrocarbon to the respective test tubes.
  • Add 10 drops of 1% aqueous potassium permanganate to each tube.
  • Mix the contents well after addition.
  • Observe the results:
    • Hexane and toluene do not react; the purple color of permanganate persists.
    • Cyclohexene and 1-hexyne react; a reaction occurs, indicated by the disappearance of the purple solution and formation of brown manganese dioxide precipitate at the liquid interface,
    • Observe the appearance of brown precipitates in the test tubes after 5 minutes of intermittent agitation.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Lecture Eight: Reaction with Potassium Permanganate PDF

Description

Explore the oxidation of alkenes and alkynes using dilute aqueous potassium permanganate. This quiz covers key concepts such as the formation of geminal diols and diketones, as well as the reaction dynamics and precipitate formation. Test your understanding of this important organic reaction!

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser