Asked in Premeth Test 18 — Alkyl Halides, Aldehydes and Ketones, Atomic Structure (20 March 2025) 2025Moderate

Identify the alkene which gives only one type of aldehyde upon ozonolysis:

Correct answer: C. 2 - butene

  • A. 1 - pentene
  • B. 2 - methyl propene
  • C. 2 - butene
  • D. 2,3 - dimethyl - 2 - butene

Explanation

You're looking for an alkene that, when cleaved by ozonolysis, produces only one type of aldehyde. This means the alkene must be symmetrical around the double bond.Here's how ozonolysis works and how it applies to each option:Ozonolysis: This reaction breaks the carbon-carbon double bond (C=C) of an alkene and forms two carbonyl compounds. If the alkene is symmetrical, the two carbonyl compounds will be identical.Let's consider each alkene:1-pentene (CH₂=CHCH₂CH₂CH₃): Ozonolysis would produce formaldehyde (HCHO) and butanal (CH₃CH₂CH₂CHO). These are two different aldehydes.2-methylpropene (CH₂=C(CH₃)CH₃): Ozonolysis would produce formaldehyde (HCHO) and acetone (CH₃COCH₃). One is an aldehyde and the other is a ketone, so they are not the same type of aldehyde.2-butene (CH₃CH=CHCH₃): Ozonolysis would produce two molecules of acetaldehyde (CH₃CHO). This is only one type of aldehyde.2,3-dimethyl-2-butene ((CH₃)₂C=C(CH₃)₂): Ozonolysis would produce acetone (CH₃COCH₃). This is a ketone, not an aldehyde.Therefore, the alkene that gives only one type of aldehyde upon ozonolysis is 2-butene

Last updated

About Alkenes

Alkenes are unsaturated hydrocarbons containing a carbon-carbon double bond with sigma and pi components and restricted rotation. Their reactions include electrophilic addition of hydrogen, halogens, hydrogen halides and water, with Markovnikov orientation, oxidation, combustion and polymerisation, while their preparation commonly involves elimination from alkyl halides or alcohols.

Practise Chemistry of Hydrocarbons

1,091 free Chemistry of Hydrocarbons MCQs from Chemistry, each with the correct answer and an explanation. Unlimited attempts, no account needed.

Exams that ask Chemistry questions like this

Chemistry is on 12 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.

Related questions