Chemistry A-Level
acylium ion
What acylium ion means in Chemistry A-Level, as defined for AQA.
Definitions of acylium ion
Exam boards and our study guides word this term in slightly different ways. Learn the version your board uses.
Check what you remember
Read the wording for your board, then hide it and explain acylium ion in your own words. Rough notes are fine. This is a self-check, with no mark or grade.
Reference: AQA
The electrophile RCO⁺ that attacks the ring, produced when AlCl₃ pulls the chloride off the acyl chloride.
Formed when RCOCl + AlCl₃ gives RCO⁺ + AlCl₄⁻, with AlCl₃ acting as a catalyst.
Topics that use acylium ion
- Electrophilic substitution (A-level only) (AQA A-Level)
Related terms
- curly arrow mechanism
- electrophile
- Halogen carrier
- nitration conditions
- nitronium ion generation
- positively charged intermediate
- reduction to amines
- temperature control
Using acylium ion in the exam
Check the command word and mark scheme for your exact question. After comparing your explanation with the reference, use the term in an answer on the linked topic. This practice does not predict an exam mark.
Practise Chemistry questions
Create a free account to answer exam-style questions on this topic and get feedback on your answers.
Start free
All Chemistry A-Level termsA week of Premium from your first lesson · Then the free plan continues · No card, no charge