
Which alkene on heating with alkaline KMnO$_4$ solution gives acetone and a gas, which turns lime water milky:
(a) 2-Methyl-2-butene
(b) Isobutylene
(c) 1-Butene
(d) 2-Butene
Answer
123k+ views
Hint: In this reaction, alkaline potassium permanganate is used. As we know it is used for the displacement of carbon-carbon double bonds. It is mainly used to identify whether hydrocarbon is alkane, or alkene. So, we can identify the alkene in this reaction.
Complete step by step solution:
> First, let us know about the alkenes. These are categorized under hydrocarbons having at least one carbon – carbon double bond.
> Now, if we talk about the given options. The mentioned options belong to the category of alkenes.
> As we know, when an alkene having two hydrogens at one end of the bond, reacts with alkaline potassium permanganate; the product obtained will be a ketone, carbon-dioxide, and water.
> So, from all the given options, when 2-methyl-2-butene, 1-butene, and 2-butene does not show reaction with alkaline potassium permanganate.
> They represent the dihydroxylation of alkenes with cold, dilute potassium permanganate to give diols.
> Thus, we can say that isobutylene reacts with alkaline KMnO$_4$. The chemical reaction is
(CH$_3$)$_2$C=CH$_2$ $\overset{alkalineKMnO_4}{\rightarrow}$ (CH$_3$)$_2$C=O + CO$_2$
So, in the end we can conclude that isobutylene alkene reacts with a solution that gives acetone, and a gas carbon-dioxide which turns lime water milky.
Hence, the correct option is (B).
Note: Don’t get confused while writing the chemical reaction. We will not consider acidified potassium permanganate solution, as it reacts too rapidly to break the carbon-carbon double bond, it is rarely used in organic chemistry. So, we have used the alkaline potassium permanganate solution for the reaction with alkene.
Complete step by step solution:
> First, let us know about the alkenes. These are categorized under hydrocarbons having at least one carbon – carbon double bond.
> Now, if we talk about the given options. The mentioned options belong to the category of alkenes.
> As we know, when an alkene having two hydrogens at one end of the bond, reacts with alkaline potassium permanganate; the product obtained will be a ketone, carbon-dioxide, and water.
> So, from all the given options, when 2-methyl-2-butene, 1-butene, and 2-butene does not show reaction with alkaline potassium permanganate.
> They represent the dihydroxylation of alkenes with cold, dilute potassium permanganate to give diols.
> Thus, we can say that isobutylene reacts with alkaline KMnO$_4$. The chemical reaction is
(CH$_3$)$_2$C=CH$_2$ $\overset{alkalineKMnO_4}{\rightarrow}$ (CH$_3$)$_2$C=O + CO$_2$
So, in the end we can conclude that isobutylene alkene reacts with a solution that gives acetone, and a gas carbon-dioxide which turns lime water milky.
Hence, the correct option is (B).
Note: Don’t get confused while writing the chemical reaction. We will not consider acidified potassium permanganate solution, as it reacts too rapidly to break the carbon-carbon double bond, it is rarely used in organic chemistry. So, we have used the alkaline potassium permanganate solution for the reaction with alkene.
Recently Updated Pages
Types of Solutions - Solution in Chemistry

Difference Between Crystalline and Amorphous Solid

JEE Main Participating Colleges 2024 - A Complete List of Top Colleges

JEE Main Maths Paper Pattern 2025 – Marking, Sections & Tips

Sign up for JEE Main 2025 Live Classes - Vedantu

JEE Main 2025 Helpline Numbers - Center Contact, Phone Number, Address

Trending doubts
JEE Main 2025 Session 2: Application Form (Out), Exam Dates (Released), Eligibility & More

JEE Main Login 2045: Step-by-Step Instructions and Details

JEE Main Exam Marking Scheme: Detailed Breakdown of Marks and Negative Marking

JEE Main 2023 January 24 Shift 2 Question Paper with Answer Keys & Solutions

JEE Main 2025: Conversion of Galvanometer Into Ammeter And Voltmeter in Physics

Physics Average Value and RMS Value JEE Main 2025

Other Pages
NCERT Solutions for Class 11 Chemistry Chapter 7 Redox Reaction

NCERT Solutions for Class 11 Chemistry Chapter 5 Thermodynamics

NCERT Solutions for Class 11 Chemistry Chapter 8 Organic Chemistry

NCERT Solutions for Class 11 Chemistry Chapter 6 Equilibrium

NCERT Solutions for Class 11 Chemistry Chapter 9 Hydrocarbons

JEE Advanced Marks vs Ranks 2025: Understanding Category-wise Qualifying Marks and Previous Year Cut-offs
