Eduqas A-Level Chemistry A410QS
Formulae and Equations
Basic Ideas About Atoms
Chemical Calculations
Bonding
Solid Structures
The Periodic Table
Simple Equilibria and Acid-Base Reactions
Thermochemistry
Rates of Reaction
The Wider Impact of Chemistry
Organic Compounds
Hydrocarbons
Halogenoalkanes
Alcohols and Carboxylic Acids
Instrumental Analysis
Redox and Standard Electrode Potential
Redox Reactions
Chemistry of the P-Block
Chemistry of the D-Block Transition Metals
Chemical Kinetics
Enthalpy Changes for Solids and Solutions
Entropy and Feasibility of Reactions
Equilibrium Constants
Acid-Base Equilibria
Stereoisomerism
Aromaticity
Alcohols and Phenols
Aldehydes and Ketones
Carboxylic Acids and Their Derivatives
Amines
Amino Acids, Peptides and Proteins
Organic Synthesis and Analysis
Specified Practical Work
Practical Skills and Techniques
Mathematical Skills in Chemistry
Halogenoalkanes
Elimination reactions forming alkenes
- 3 things to know
- Components 1 and 2
Overview
Recall questions on the reagent and conditions for elimination, the hydroxide ion acting as a base rather than a nucleophile, the equations and the products besides the alkene, why some halogenoalkanes give two alkenes, which class gives the most elimination, and how the solvent decides the outcome.
What you need to know
Answer each one before you reveal it.
Describe the three curly arrows in the elimination of hydrogen bromide from 1-bromopropane.
Name the class of organic product formed when a halogenoalkane undergoes elimination.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Name the class of organic product formed when a halogenoalkane undergoes elimination.
Model answer
An alkene is formed.
- 2
State the reagent and conditions needed for the elimination reaction of a halogenoalkane.
Model answer
Potassium hydroxide dissolved in ethanol is used, and the mixture is heated under reflux.
- 3
Write the equation for the elimination of hydrogen bromide from 1-bromopropane by ethanolic potassium hydroxide.
Model answer
CH₃CH₂CH₂Br + KOH → CH₃CH=CH₂ + KBr + H₂O.
- 4
In an elimination reaction, is the hydroxide ion acting as a nucleophile or as a base?
Model answer
It acts as a base, because it removes a hydrogen ion rather than bonding to a carbon atom.
- 5
From which carbon atom is the hydrogen removed during an elimination reaction?
Model answer
It is removed from a carbon atom next to the one carrying the halogen.
- 6
Describe the three curly arrows in the elimination of hydrogen bromide from 1-bromopropane.
Model answer
One arrow runs from a lone pair on the hydroxide ion to the hydrogen on the carbon next to the C—Br, a second runs from that C—H bond into the gap between the two carbons to form the double bond, and a third runs from the C—Br bond to the bromine atom.
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