Organic Chemistry question
Hi,
in this question would it be ok to have the esterification of both the phenol group and the alcohol group giving a structure with three benzene rings?
Thanks
in this question would it be ok to have the esterification of both the phenol group and the alcohol group giving a structure with three benzene rings?
Thanks
To form an ester, you need a carboxylic acid group: of which there is only one. That can esterify with an OH group of which there are two. The MS allowed either one to form. One COOH group cannot form two ester groups simultaneously.
You perhaps also should know that phenol groups don't easily esterify; needing something like RCOCl to make it happen.
You perhaps also should know that phenol groups don't easily esterify; needing something like RCOCl to make it happen.
Original post by Pigster
To form an ester, you need a carboxylic acid group: of which there is only one. That can esterify with an OH group of which there are two. The MS allowed either one to form. One COOH group cannot form two ester groups simultaneously.
You perhaps also should know that phenol groups don't easily esterify; needing something like RCOCl to make it happen.
You perhaps also should know that phenol groups don't easily esterify; needing something like RCOCl to make it happen.
Thanks,
So how do you know that there isnt more than 1 molecule with the COOH group available?
Compound A is oxidised. The CHO group -> COOH, the phenol group won't oxidise.
Compound A is then reduced. The CHO group -> CH2OH, the phenol group won't oxidise.
The COOH group on the oxidised version of A can react with either OH group on C (but essentially won't react with the phenol group, but the MS allowed it).
The only other reaction that could take place would be the polymerisation of the oxidised version of A (but that involves esterification through a phenol group, which I might have mentioned is unlikely).
Adding another CH2OH to A just gives the one COOH group on the oxidised version of A another possible target.
Compound A is then reduced. The CHO group -> CH2OH, the phenol group won't oxidise.
The COOH group on the oxidised version of A can react with either OH group on C (but essentially won't react with the phenol group, but the MS allowed it).
The only other reaction that could take place would be the polymerisation of the oxidised version of A (but that involves esterification through a phenol group, which I might have mentioned is unlikely).
Adding another CH2OH to A just gives the one COOH group on the oxidised version of A another possible target.
Original post by Pigster
Compound A is oxidised. The CHO group -> COOH, the phenol group won't oxidise.
Compound A is then reduced. The CHO group -> CH2OH, the phenol group won't oxidise.
The COOH group on the oxidised version of A can react with either OH group on C (but essentially won't react with the phenol group, but the MS allowed it).
The only other reaction that could take place would be the polymerisation of the oxidised version of A (but that involves esterification through a phenol group, which I might have mentioned is unlikely).
Adding another CH2OH to A just gives the one COOH group on the oxidised version of A another possible target.
Compound A is then reduced. The CHO group -> CH2OH, the phenol group won't oxidise.
The COOH group on the oxidised version of A can react with either OH group on C (but essentially won't react with the phenol group, but the MS allowed it).
The only other reaction that could take place would be the polymerisation of the oxidised version of A (but that involves esterification through a phenol group, which I might have mentioned is unlikely).
Adding another CH2OH to A just gives the one COOH group on the oxidised version of A another possible target.
Thanks, i understand that there is one COOH group on that molecule but if you had two of them molecules would there not be two COOH groups available to oxidise either of the Oh groups (as they allowed the esterification of the phenol group)... which could potentially lead to a molecule with 3 benzene rings (two ester groups) or do you have to treat it as just one molecule available .. or is it just not possible to have one ester group of the alcohol group and one on the phenol group even if there were two molecules available
If one molecule started off with two CHO groups and was completely oxidised, it would form two COOH groups and could then form two ester linkages to C and the resulting molecule would have three benzene rings.
You were correct all along. If only you'd have explained yourself better at the beginning
You were correct all along. If only you'd have explained yourself better at the beginning
Sorry i have not explained this well at all. Basically what I cant understand is why the molecule with two OH groups does not produce a molecule with three benzene rings ( two ester groups) given a reaction with the COOH molecule they gave in the question.
The way i am thinking is 1 molecule of the one with two OH groups it reacted with 2 molecules of the one with the (one) COOH group and what will happen is that the two COOH groups (one from each molecule) which are available (because there are two molecules) will join onto the two OH groups in the molecule (one on the phenol and one on the CH2OH group)
Does this just not happen or does the flow diagram show that there is only one molecule with a COOH group available.
The way i am thinking is 1 molecule of the one with two OH groups it reacted with 2 molecules of the one with the (one) COOH group and what will happen is that the two COOH groups (one from each molecule) which are available (because there are two molecules) will join onto the two OH groups in the molecule (one on the phenol and one on the CH2OH group)
Does this just not happen or does the flow diagram show that there is only one molecule with a COOH group available.
(edited 6 years ago)
Original post by Pigster
Aha, you mean one benzene ring with two alcohol groups which react with separate molecules each with a COOH group to form a molecule with three benzene rings.
That'd work.
That'd work.
Yes thats it
. is there a reason why this would not be accepted?Original post by 111davey1
Yes thats it . is there a reason why this would not be accepted?
. is there a reason why this would not be accepted?Quite simply it is because compound A cannot be converted into a molecule with two COOH groups.
The phenol group cannot be oxidised.
Original post by Pigster
Quite simply it is because compound A cannot be converted into a molecule with two COOH groups.
The phenol group cannot be oxidised.
The phenol group cannot be oxidised.
Thanks,
But this doesnt make sense to me because that molecule is reacting with a molecule with 2 OH groups so surely if a bunch of them molecules were together you would find some where both oh groups on that molecule had been esterified by compound A. , on the same molecule leading to a compound with three benzene rings.
Is it that it is implying that one molecule of A is reacting with one of C?
To quote me earlier:
Two oxidised versions of A, each having a COOH group could, in theory, react with one molecule of compound C (which has two OH groups) forming a molecule with three benzene rings.
As I (almost) said earlier, that'd work.
Except in this case it wouldn't as phenol groups don't like esterifying. The old OCR A spec didn't worry about that, but now that we've got acyl chlorides, they do: 6.1.3(f) additional guidance: "esterification of phenol, which is not readily esterified by carboxylic acids"
Original post by Pigster
Aha, you mean one benzene ring with two alcohol groups which react with separate molecules each with a COOH group to form a molecule with three benzene rings.
That'd work.
That'd work.
Two oxidised versions of A, each having a COOH group could, in theory, react with one molecule of compound C (which has two OH groups) forming a molecule with three benzene rings.
As I (almost) said earlier, that'd work.
Except in this case it wouldn't as phenol groups don't like esterifying. The old OCR A spec didn't worry about that, but now that we've got acyl chlorides, they do: 6.1.3(f) additional guidance: "esterification of phenol, which is not readily esterified by carboxylic acids"
Original post by 111davey1
Thanks,
But this doesnt make sense to me because that molecule is reacting with a molecule with 2 OH groups so surely if a bunch of them molecules were together you would find some where both oh groups on that molecule had been esterified by compound A. , on the same molecule leading to a compound with three benzene rings.
Is it that it is implying that one molecule of A is reacting with one of C?
But this doesnt make sense to me because that molecule is reacting with a molecule with 2 OH groups so surely if a bunch of them molecules were together you would find some where both oh groups on that molecule had been esterified by compound A. , on the same molecule leading to a compound with three benzene rings.
Is it that it is implying that one molecule of A is reacting with one of C?
Given that the mark scheme says to allow esterification of the phenol oxygen, you should be absolutely fine if you suggested both esterifications.
In reality the phenol oxygen lone pairs are able to delocalise around the aromatic ring and so this esterification would be very slow compared to esterification of the alcohol group!
edit:seems like from what pigster has said, these days Phenol esterification is not kosher (quite rightly) but at least now you know
(edited 6 years ago)
Quick Reply
Related discussions
- Tips for physical A level chemistry OCR A?
- AS/A Level Chemistry Study Group 2023/2024
- Learning techniques
- OCR A Chemistry Predictions
- How should I study organic chemistry?
- Bath Mpharm Interview Questions
- Inorganic Chemistry (AQA) - A level
- a level biology and chemustry
- Sunderland uni Mpharm interview
- A level chemistry for a biology degree? (help please!!)
- should i give up?
- Biochem to Med chem
- A-level chem help
- Chemistry at Uni?
- What is it like doing chem vs natural sciences at uni?
- Chem alevel
- Chemistry or Biochemistry?
- Is Chemistry better at A-level than at GCSE?
- I have been struggling with my a levels, how do I improve?
- how to revise ?
Latest
Trending
Last reply 1 week ago
Im confused about this chemistry question, why does it form these productsTrending
Last reply 1 week ago
Im confused about this chemistry question, why does it form these products
