These videos are so amazing, they're so useful in recapping content and filling in gaps where teachers couldn't teach topics face to face due to covid, thank you!
For the Nucleophilic Addition-Elimination slide, the example says ethanol but the displayed formula for the alcohol is methanol... So for ethanol would the products be ethyl propanoate and HCl? Thank you :)
Do we need to memorise that making Aspirin equation? The spec just says we need to know the advantages of using ethanoic anhydride over ethanoyl chloride.
I'm doing a different exam board ccea which isn't really well known as its only in northern Ireland and I can say this video really reallly helped me understand this topic . Thank u so muchhhh
Hi there, on the Acyl Chloride Nucleophilic Addition-Elimination Reaction why does the reforming of the Oxygen double bond have the arrow pointing into the bond and not the Carbon? I thought it always had to point into the centre of an atom? Thank you so much for your help. You are a lifesaver
Hi lily. My understanding is at the start of mechanism, the very electron deficient (&+) carbon atom in COCl is highly susceptible to nucleophilic attack (nucleus loving), making acyl chlorides most reactive! - in this example, by methanol (he said ethanol in video but drew methanol by mistake i think). Since methanol acts as the nucleophile, the first step shows a curly arrow moving from one of the lone pairs on the electronegative oxygen atom in methanol towards the &+ charge on the electron deficient carbon atom of COCl group (arrow ALWAYS shows direction of electron movement for organic mechanisms), forming a new bond with acyl chloride molecule! But since first step is an addition reaction, the C atom in the acyl chloride now has one too many bonds! So the C=O bond in COCl group has to temporarily break and one of electron pairs in C=O double bond moves towards the electronegative (&-) oxygen atom (shown as curly arrow moving from C=O bond to O atom) forming C-O single bond now (so carbon again forms only 4 bonds) but leaving single negative charge on oxygen! Since this is a highly unstable molecule formed, the newly formed electron pair on O atom must immediately move back to reform the C=O bond - shown by curly arrow moving from lone pair on negative O atom back into C-O bond so reforming C=O again. Does this answer your initial question about why arrow moves back into the C=O bond? And not back towards the &+ C atom itself like in the initial nucleophilic addition step where new bond was formed with methanol (acting as nucleophile)? (In the final elimination step- To satisfy the C atom in acyl chloride part forming only 4 bonds again, the C-Cl bond breaks (heterolytically) instead of C=O again since chlorine atom is also electronegative (shown by curly arrow moving from electron pair in C-Cl bond onto Cl atom) forming a chloride ion Cl- (with extra lone pair of electrons). The Cl- ion then removes H atom from O-H bond in attached methanol ( with a curly arrow showing electron pair in O-H bond moving back onto O atom, thereby neutralising the temporary positive charge on O atom in methanol part). This is the final elimination step where hydrogen chloride is removed, leaving behind the newly formed ester! Ps This mechanism is much harder than a normal esterification reaction involving an alcohol and carboxylic acid (nucleophilic subsitution), as reaction between alcohol and acid chloride is two step (nucleophilic addition-elimination)! But don't worry this is the hardest mechanism you will come across in organic chemistry at A-level (to quote chris). I hope this helps! And hope Chris doesn't mind me answering your question - please feel free to add anything or correct if need be. As this is particularly challenging mechanism!
the specification says: "Students should be able to outline the mechanisms of: these nucleophilic substitution reactions the nucleophilic addition-elimination reactions of ammonia and primary amines with acyl chlorides."
I am committed to taking the October chemistry A-level and proving the government wrong. These videos are literally saving me thank you so much. :)
You're welcome and good luck with your resit!
how did they go? i hope it went well!
who disliked?? this video is great, thank you so much!
this really saves me. im suffering when i go through this topic
Thank you so so much for doing this. As a mature student self teaching, these videos have been an invaluable resource.
You're very welcome!
42:31 the question says ‘ethanol’ but the mechanism shows methanol- just a heads up :)
Had to pick up the smallest little detail 😂
oh dam im glad u said cuz i sat there for 2mins questioning myself on ethanol and methanol
These videos are so amazing, they're so useful in recapping content and filling in gaps where teachers couldn't teach topics face to face due to covid, thank you!
Coweeeed
For the Nucleophilic Addition-Elimination slide, the example says ethanol but the displayed formula for the alcohol is methanol... So for ethanol would the products be ethyl propanoate and HCl? Thank you :)
not sure but i think it's ethyl ethanoate cuz the ester is CH₃CO₂CH₂CH₃, but yea + hcl
Do we need to memorise that making Aspirin equation? The spec just says we need to know the advantages of using ethanoic anhydride over ethanoyl chloride.
I'm doing a different exam board ccea which isn't really well known as its only in northern Ireland and I can say this video really reallly helped me understand this topic . Thank u so muchhhh
Thank you so much sir, your hard work is greatly appreciated ❤
No problem 😊
Who else is revising to do year 13 exams after September
me!
Hi @Allery Chemistry. Thank you for this amazing job. Isn't basic hydrolysis of esters an irreversible reaction ? Please correct me if i'm wrong
I agree with you, is that right?
Brilliant
Thanks. Pleased you found it helpful!
I hate organic. Paper 2 will be my downfall.
same
Its over for me
Thank you for another great video!☺
You're welcome 😊
Thank you for these! Super helpful:)
Glad you like them!
I love your videos they are so good
Hi sir, for acyl chlorides reacting with a primary amine, wouldn't it be CH3NH3+CL- instead of HCL
Chemguide states very little HCl as any formed would react with the amine and form and salt.
Hi there, on the Acyl Chloride Nucleophilic Addition-Elimination Reaction why does the reforming of the Oxygen double bond have the arrow pointing into the bond and not the Carbon? I thought it always had to point into the centre of an atom? Thank you so much for your help. You are a lifesaver
Hi lily. My understanding is at the start of mechanism, the very electron deficient (&+) carbon atom in COCl is highly susceptible to nucleophilic attack (nucleus loving), making acyl chlorides most reactive! - in this example, by methanol (he said ethanol in video but drew methanol by mistake i think).
Since methanol acts as the nucleophile, the first step shows a curly arrow moving from one of the lone pairs on the electronegative oxygen atom in methanol towards the &+ charge on the electron deficient carbon atom of COCl group (arrow ALWAYS shows direction of electron movement for organic mechanisms), forming a new bond with acyl chloride molecule!
But since first step is an addition reaction, the C atom in the acyl chloride now has one too many bonds! So the C=O bond in COCl group has to temporarily break and one of electron pairs in C=O double bond moves towards the electronegative (&-) oxygen atom (shown as curly arrow moving from C=O bond to O atom) forming C-O single bond now (so carbon again forms only 4 bonds) but leaving single negative charge on oxygen!
Since this is a highly unstable molecule formed, the newly formed electron pair on O atom must immediately move back to reform the C=O bond - shown by curly arrow moving from lone pair on negative O atom back into C-O bond so reforming C=O again.
Does this answer your initial question about why arrow moves back into the C=O bond? And not back towards the &+ C atom itself like in the initial nucleophilic addition step where new bond was formed with methanol (acting as nucleophile)?
(In the final elimination step- To satisfy the C atom in acyl chloride part forming only 4 bonds again, the C-Cl bond breaks (heterolytically) instead of C=O again since chlorine atom is also electronegative (shown by curly arrow moving from electron pair in C-Cl bond onto Cl atom) forming a chloride ion Cl- (with extra lone pair of electrons). The Cl- ion then removes H atom from O-H bond in attached methanol ( with a curly arrow showing electron pair in O-H bond moving back onto O atom, thereby neutralising the temporary positive charge on O atom in methanol part). This is the final elimination step where hydrogen chloride is removed, leaving behind the newly formed ester!
Ps This mechanism is much harder than a normal esterification reaction involving an alcohol and carboxylic acid (nucleophilic subsitution), as reaction between alcohol and acid chloride is two step (nucleophilic addition-elimination)! But don't worry this is the hardest mechanism you will come across in organic chemistry at A-level (to quote chris).
I hope this helps! And hope Chris doesn't mind me answering your question - please feel free to add anything or correct if need be. As this is particularly challenging mechanism!
In the base hydrolysis equation, no water was used on the hydroxide ions, why ?
not sure but maybe cuz it broke O-H in NaOH. H then bond with RO to form an alcohol = ROH (?)
Wonderful
for AQA do we need to know base hydrolysis mechanism
Thank you so so so much
at the end, is that required practical 10?
10a
so cooked
im learning that now, you’ll be fine 😭
Do we need to know the mechanisms for the Acid Anhydride reactions, or only the Acyl Chloride reactions? (AQA)
only acyl chloride
no, the spec says acyl chloride use it it helps to check :)
the specification says: "Students should be able to outline the mechanisms of:
these nucleophilic substitution reactions
the nucleophilic addition-elimination reactions of ammonia and primary amines with acyl chlorides."
so is biodiesel the methyl ester or a faty acid? 29:50
it is a mixture of different fatty acid methyl esters, so aka mixture of methyl ester of longpchain carboxylic acids.
Bio diesel is the methyl ester
The methyl ester
thank you🥰🥰🥰
You’re welcome 😊