Subjects
Careers
Maths
Biology
Chemistry
English Lang.
History
Infection and response
Responding to change (a2 only)
Energy transfers (a2 only)
Homeostasis and response
Cell biology
Biological molecules
Organisation
Substance exchange
The control of gene expression (a2 only)
Bioenergetics
Genetic information & variation
Inheritance, variation and evolution
Genetics & ecosystems (a2 only)
Ecology
Cells
Show all topics
World war two & the holocaust
2m wars and welfare: britain in transition, 1906-1957
2o democracy and nazism: germany, 1918-1945
1f industrialisation and the people: britain, c1783-1885
Medieval period: 1066 -1509
Britain & the wider world: 1745 -1901
2d religious conflict and the church in england, c1529-c1570
1l the quest for political stability: germany, 1871-1991
The cold war
1c the tudors: england, 1485-1603
Inter-war germany
2n revolution and dictatorship: russia, 1917-1953
2s the making of modern britain, 1951-2007
World war one
Britain: 1509 -1745
Show all topics
22
0
Zara
04/09/2025
Chemistry
AQA a level chemistry mechanisms
874
•
4 Sept 2025
•
Zara
@zara_ccce
A comprehensive guide to organic chemistry reactions focusing on addition,... Show more
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
This page covers several important reaction types including acid catalyzed addition hydration of ethene and free radical substitution mechanisms. The content emphasizes the step-wise nature of organic reactions.
Definition: Free radical substitution occurs through three distinct steps: initiation, propagation, and termination.
Example: The free radical bromination of methane proceeds through a chain reaction mechanism initiated by UV light.
Highlight: The propagation step demonstrates how radical chain reactions can be self-sustaining once initiated.
Vocabulary: Propagation - the main reaction cycle in a radical chain mechanism where reactive intermediates are continuously regenerated.
The third page explores nucleophilic addition and addition-elimination reactions, with particular focus on reactions involving ammonia and cyanide ions.
Definition: Nucleophilic addition involves the attack of an electron-rich species (nucleophile) on an electron-deficient carbon.
Example: The reaction of ammonia with carbonyls to form primary amines demonstrates nucleophilic addition followed by elimination.
Highlight: The formation of cyanohydrins shows how nucleophilic addition can create new carbon-carbon bonds.
The final page details aromatic substitution reactions, including nitration and the Friedel-Crafts acylation mechanism.
Definition: Electrophilic aromatic substitution involves the replacement of a hydrogen atom on an aromatic ring with an electrophile.
Example: The nitration of aromatic compounds using nitric acid and sulfuric acid demonstrates the formation and reaction of the nitronium ion (NO₂⁺).
Highlight: The Friedel-Crafts acylation requires aluminum chloride as a Lewis acid catalyst to generate the active electrophile.
Vocabulary: Electrophile - a chemical species that accepts electron pairs in chemical bonds.
The first page introduces fundamental electrophilic addition reactions, particularly focusing on reactions with bromine and sulfuric acid. The mechanisms show the step-by-step addition of reactants across double bonds.
Definition: Electrophilic addition is a reaction where an electrophile (electron-seeking species) adds across a carbon-carbon double bond.
Example: The addition of bromine (Br₂) to an alkene produces a dibrominated product through a cyclic bromonium ion intermediate.
Highlight: The reaction mechanism demonstrates the importance of electron movement and intermediate formation in organic chemistry reactions.
Vocabulary: Bromonium ion - a cyclic intermediate formed during bromine addition to alkenes.
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
App Store
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
Zara
@zara_ccce
A comprehensive guide to organic chemistry reactions focusing on addition, substitution, and elimination mechanisms, with detailed explanations of electrophilic addition with bromine, acid catalyzed addition hydration of ethene, and Friedel-Crafts acylation mechanism.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
This page covers several important reaction types including acid catalyzed addition hydration of ethene and free radical substitution mechanisms. The content emphasizes the step-wise nature of organic reactions.
Definition: Free radical substitution occurs through three distinct steps: initiation, propagation, and termination.
Example: The free radical bromination of methane proceeds through a chain reaction mechanism initiated by UV light.
Highlight: The propagation step demonstrates how radical chain reactions can be self-sustaining once initiated.
Vocabulary: Propagation - the main reaction cycle in a radical chain mechanism where reactive intermediates are continuously regenerated.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
The third page explores nucleophilic addition and addition-elimination reactions, with particular focus on reactions involving ammonia and cyanide ions.
Definition: Nucleophilic addition involves the attack of an electron-rich species (nucleophile) on an electron-deficient carbon.
Example: The reaction of ammonia with carbonyls to form primary amines demonstrates nucleophilic addition followed by elimination.
Highlight: The formation of cyanohydrins shows how nucleophilic addition can create new carbon-carbon bonds.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
The final page details aromatic substitution reactions, including nitration and the Friedel-Crafts acylation mechanism.
Definition: Electrophilic aromatic substitution involves the replacement of a hydrogen atom on an aromatic ring with an electrophile.
Example: The nitration of aromatic compounds using nitric acid and sulfuric acid demonstrates the formation and reaction of the nitronium ion (NO₂⁺).
Highlight: The Friedel-Crafts acylation requires aluminum chloride as a Lewis acid catalyst to generate the active electrophile.
Vocabulary: Electrophile - a chemical species that accepts electron pairs in chemical bonds.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
The first page introduces fundamental electrophilic addition reactions, particularly focusing on reactions with bromine and sulfuric acid. The mechanisms show the step-by-step addition of reactants across double bonds.
Definition: Electrophilic addition is a reaction where an electrophile (electron-seeking species) adds across a carbon-carbon double bond.
Example: The addition of bromine (Br₂) to an alkene produces a dibrominated product through a cyclic bromonium ion intermediate.
Highlight: The reaction mechanism demonstrates the importance of electron movement and intermediate formation in organic chemistry reactions.
Vocabulary: Bromonium ion - a cyclic intermediate formed during bromine addition to alkenes.
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
App Store
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
