Home >
Community >
Catalytic Hydrogenation Of Carboxylic Acid..!
Upvote
VOTE
Downvote
+ Organic
Posted by
Mark Andrew Guy
Catalytic Hydrogenation Of Carboxylic Acid..!
Babcock_Hall Brother , Listen ..!!!
As far as I know Catalytical Hydrogenation take place by radical mechanism , so Leaving group ability will not have so much influence on reaction . As in this is case Homogeneous cleavage take place , heterogeneous cleavage will not..!!!
So why we are concerning about leaving group ability
As far as I know Catalytical Hydrogenation take place by radical mechanism , so Leaving group ability will not have so much influence on reaction . As in this is case Homogeneous cleavage take place , heterogeneous cleavage will not..!!!
So why we are concerning about leaving group ability
There is a nice new method, but from esters, which are easy to prepare. see Iron-Catalyzed Hydrogenation of Esters to Alcohols. (2014). Iron-Catalyzed Hydrogenation of Esters to Alcohols., 53(48), 13004–13006. doi:10.1002/anie.201407613 for the method
There is a nice new method, but from esters, which are easy to prepare. see Iron-Catalyzed Hydrogenation of Esters to Alcohols. (2014). Iron-Catalyzed Hydrogenation of Esters to Alcohols., 53(48), 13004–13006. doi:10.1002/anie.201407613 for the method
This is something of a tangent, but when one uses a less active reducing agent, ones has to use an ester with a decent leaving group, such as phenoxide ion.
Ohk thats ok if ester having leaving group such as phenoxide (PhO-) or methoxide (OCH3-) they are pretty much good leaving group than Hydroxide (OH-) .
For groups whose structures are similar, one can use basicity to estimate leaving group ability. Which is more basic, methoxide or phenoxide?
Methoxide is more basic , As in case of phenoxide the lone pair are in conjugation .
This is something of a tangent, but when one uses a less active reducing agent, ones has to use an ester with a decent leaving group, such as phenoxide ion.
Ohk thats ok if ester having leaving group such as phenoxide (PhO-) or methoxide (OCH3-) they are pretty much good leaving group than Hydroxide (OH-) .
For groups whose structures are similar, one can use basicity to estimate leaving group ability. Which is more basic, methoxide or phenoxide?
Methoxide is more basic , As in case of phenoxide the lone pair are in conjugation .
This is something of a tangent, but when one uses a less active reducing agent, ones has to use an ester with a decent leaving group, such as phenoxide ion.
Ohk thats ok if ester having leaving group such as phenoxide (PhO-) or methoxide (OCH3-) they are pretty much good leaving group than Hydroxide (OH-) .
For groups whose structures are similar, one can use basicity to estimate leaving group ability. Which is more basic, methoxide or phenoxide?
This is something of a tangent, but when one uses a less active reducing agent, ones has to use an ester with a decent leaving group, such as phenoxide ion.
Ohk thats ok if ester having leaving group such as phenoxide (PhO-) or methoxide (OCH3-) they are pretty much good leaving group than Hydroxide (OH-) .
For groups whose structures are similar, one can use basicity to estimate leaving group ability. Which is more basic, methoxide or phenoxide?
You can chemoselectively reduce carboxylic acids to alcohols (and amides to amines) with BH3, like this:
Your second question is absolutely impossible to get answered in a short way... What reducing agent is better depends much on the situation: What functional group/s are you trying to reduce, which other groups are present on the molecule and you don't want them to get reduced...
You can chemoselectively reduce carboxylic acids to alcohols (and amides to amines) with BH3, like this:
Your second question is absolutely impossible to get answered in a short way... What reducing agent is better depends much on the situation: What functional group/s are you trying to reduce, which other groups are present on the molecule and you don't want them to get reduced...
Im not sure about your 1st question but about the second.. It depends. LAH is probably easier to work with since it is a powder while H2 is gas and requires special setup. There is no easy answer on this question, it depends on many factors but generaly speaking, by using H2 you can reduce pretty much anything you want into anything you want, but you need to have the right conditions
Im not sure about your 1st question but about the second.. It depends. LAH is probably easier to work with since it is a powder while H2 is gas and requires special setup. There is no easy answer on this question, it depends on many factors but generaly speaking, by using H2 you can reduce pretty much anything you want into anything you want, but you need to have the right conditions
I believe catalytic hydrogenation doesn't actually take place by a radical mechanism but this is a different discussion.
In any case, the carboxyl group seems to display very different reactivity to ester groups and is pretty much in the bottom rung of reactivity against reducing agents including H2 and even LiAlH4, with the exception of BH3.
The metals used in catalytic hydrogenation actually occasionally display curiously different chemoselectivities for different reducible substrates, although there is a general list of reactivity against said substrates that applies. The list has carboxylic acids smack bang at the bottom with esters being pretty challenging substrates also. This would perhaps be to do with their poor capacities to dock to the metal surface - important in the hydrog process.
I believe catalytic hydrogenation doesn't actually take place by a radical mechanism but this is a different discussion.
In any case, the carboxyl group seems to display very different reactivity to ester groups and is pretty much in the bottom rung of reactivity against reducing agents including H2 and even LiAlH4, with the exception of BH3.
The metals used in catalytic hydrogenation actually occasionally display curiously different chemoselectivities for different reducible substrates, although there is a general list of reactivity against said substrates that applies. The list has carboxylic acids smack bang at the bottom with esters being pretty challenging substrates also. This would perhaps be to do with their poor capacities to dock to the metal surface - important in the hydrog process.
This is something of a tangent, but when one uses a less active reducing agent, ones has to use an ester with a decent leaving group, such as phenoxide ion.
Ohk thats ok if ester having leaving group such as phenoxide (PhO-) or methoxide (OCH3-) they are pretty much good leaving group than Hydroxide (OH-) .
For groups whose structures are similar, one can use basicity to estimate leaving group ability. Which is more basic, methoxide or phenoxide?
Methoxide is more basic , As in case of phenoxide the lone pair are in conjugation .
This is something of a tangent, but when one uses a less active reducing agent, ones has to use an ester with a decent leaving group, such as phenoxide ion.
Ohk thats ok if ester having leaving group such as phenoxide (PhO-) or methoxide (OCH3-) they are pretty much good leaving group than Hydroxide (OH-) .
For groups whose structures are similar, one can use basicity to estimate leaving group ability. Which is more basic, methoxide or phenoxide?
Methoxide is more basic , As in case of phenoxide the lone pair are in conjugation .
Im not sure about your 1st question but about the second.. It depends. LAH is probably easier to work with since it is a powder while H2 is gas and requires special setup. There is no easy answer on this question, it depends on many factors but generally speaking, by using H2 you can reduce pretty much anything you want into anything you want, but you need to have the right conditions
Ok That means We can use both method to reduce .!! Thanks By the way we can reduce Carboxylic acid to Alcohol by Using LAH but i didn't find anywhere where reduction of Carboxylic acid by Catalytical Hydrogenation can take place..!!
Can Anybody Help me on my another Doubt No one is replying http://www.chemicalforums.com/index.php?topic=78907.0
Im not sure about your 1st question but about the second.. It depends. LAH is probably easier to work with since it is a powder while H2 is gas and requires special setup. There is no easy answer on this question, it depends on many factors but generally speaking, by using H2 you can reduce pretty much anything you want into anything you want, but you need to have the right conditions
Ok That means We can use both method to reduce .!! Thanks By the way we can reduce Carboxylic acid to Alcohol by Using LAH but i didn't find anywhere where reduction of Carboxylic acid by Catalytical Hydrogenation can take place..!!
Can Anybody Help me on my another Doubt No one is replying http://www.chemicalforums.com/index.php?topic=78907.0
This is something of a tangent, but when one uses a less active reducing agent, ones has to use an ester with a decent leaving group, such as phenoxide ion.
Ohk thats ok if ester having leaving group such as phenoxide (PhO-) or methoxide (OCH3-) they are pretty much good leaving group than Hydroxide (OH-) .
But If you have ester having Higher Substituents like pentoxide (OC5H11-) they are bad Leaving group due to large +I effect .
So I can conclude that We can't replace OH by anything it should be either OMe or OPh ..!! Am i right ?? But as far i know catalytical hydrogenation occurs through radical Mechanism ..!! So I think leaving group ability nothing to do with Hydrogenation .!!!
Can anybody How It get Reduce to Alcohol ?? RCOOR' + H2 RCH2OH + R'OH
First A Pi bond is breaks Radical forms and 2 Hydrogen get inserted but what will happen next ?? Can It Break Sigma bond ??
This is something of a tangent, but when one uses a less active reducing agent, ones has to use an ester with a decent leaving group, such as phenoxide ion.
Ohk thats ok if ester having leaving group such as phenoxide (PhO-) or methoxide (OCH3-) they are pretty much good leaving group than Hydroxide (OH-) .
But If you have ester having Higher Substituents like pentoxide (OC5H11-) they are bad Leaving group due to large +I effect .
So I can conclude that We can't replace OH by anything it should be either OMe or OPh ..!! Am i right ?? But as far i know catalytical hydrogenation occurs through radical Mechanism ..!! So I think leaving group ability nothing to do with Hydrogenation .!!!
Can anybody How It get Reduce to Alcohol ?? RCOOR' + H2 RCH2OH + R'OH
First A Pi bond is breaks Radical forms and 2 Hydrogen get inserted but what will happen next ?? Can It Break Sigma bond ??
There is a nice new method, but from esters, which are easy to prepare. see Iron-Catalyzed Hydrogenation of Esters to Alcohols. (2014). Iron-Catalyzed Hydrogenation of Esters to Alcohols., 53(48), 13004–13006. doi:10.1002/anie.201407613 for the method
Thank you very much
But i have same question why we can't use Carboxylic acid ?? Why usually we have to convert carboxylic acid into ester first ??
There is a nice new method, but from esters, which are easy to prepare. see Iron-Catalyzed Hydrogenation of Esters to Alcohols. (2014). Iron-Catalyzed Hydrogenation of Esters to Alcohols., 53(48), 13004–13006. doi:10.1002/anie.201407613 for the method
Thank you very much
But i have same question why we can't use Carboxylic acid ?? Why usually we have to convert carboxylic acid into ester first ??
This is something of a tangent, but when one uses a less active reducing agent, ones has to use an ester with a decent leaving group, such as phenoxide ion.
This is something of a tangent, but when one uses a less active reducing agent, ones has to use an ester with a decent leaving group, such as phenoxide ion.
Your second question is absolutely impossible to get answered in a short way... What reducing agent is better depends much on the situation: What functional group/s are you trying to reduce, which other groups are present on the molecule and you don't want them to get reduced...
Ok So that means both have their own advantages . Can you prefer me any link or book where i can get the information about reducing properties of different reducing agents ?? and what about reactivity order of these metals ?? Pd , Pt , Rh , Ni , Ru
Your second question is absolutely impossible to get answered in a short way... What reducing agent is better depends much on the situation: What functional group/s are you trying to reduce, which other groups are present on the molecule and you don't want them to get reduced...
Ok So that means both have their own advantages . Can you prefer me any link or book where i can get the information about reducing properties of different reducing agents ?? and what about reactivity order of these metals ?? Pd , Pt , Rh , Ni , Ru
As far as I know Catalytical Hydrogenation take place by radical mechanism , so Leaving group ability will not have so much influence on reaction . As in this is case Homogeneous cleavage take place , heterogeneous cleavage will not..!!!
So why we are concerning about leaving group ability
As far as I know Catalytical Hydrogenation take place by radical mechanism , so Leaving group ability will not have so much influence on reaction . As in this is case Homogeneous cleavage take place , heterogeneous cleavage will not..!!!
So why we are concerning about leaving group ability
More
VOTE
see Iron-Catalyzed Hydrogenation of Esters to Alcohols. (2014). Iron-Catalyzed Hydrogenation of Esters to Alcohols., 53(48), 13004–13006. doi:10.1002/anie.201407613
for the method
see Iron-Catalyzed Hydrogenation of Esters to Alcohols. (2014). Iron-Catalyzed Hydrogenation of Esters to Alcohols., 53(48), 13004–13006. doi:10.1002/anie.201407613
for the method
More
VOTE
More
VOTE
More
VOTE
Your second question is absolutely impossible to get answered in a short way...
What reducing agent is better depends much on the situation: What functional group/s are you trying to reduce, which other groups are present on the molecule and you don't want them to get reduced...
Your second question is absolutely impossible to get answered in a short way...
What reducing agent is better depends much on the situation: What functional group/s are you trying to reduce, which other groups are present on the molecule and you don't want them to get reduced...
More
VOTE
It depends. LAH is probably easier to work with since it is a powder while H2 is gas and requires special setup. There is no easy answer on this question, it depends on many factors but generaly speaking, by using H2 you can reduce pretty much anything you want into anything you want, but you need to have the right conditions
It depends. LAH is probably easier to work with since it is a powder while H2 is gas and requires special setup. There is no easy answer on this question, it depends on many factors but generaly speaking, by using H2 you can reduce pretty much anything you want into anything you want, but you need to have the right conditions
More
VOTE
In any case, the carboxyl group seems to display very different reactivity to ester groups and is pretty much in the bottom rung of reactivity against reducing agents including H2 and even LiAlH4, with the exception of BH3.
The metals used in catalytic hydrogenation actually occasionally display curiously different chemoselectivities for different reducible substrates, although there is a general list of reactivity against said substrates that applies. The list has carboxylic acids smack bang at the bottom with esters being pretty challenging substrates also. This would perhaps be to do with their poor capacities to dock to the metal surface - important in the hydrog process.
In any case, the carboxyl group seems to display very different reactivity to ester groups and is pretty much in the bottom rung of reactivity against reducing agents including H2 and even LiAlH4, with the exception of BH3.
The metals used in catalytic hydrogenation actually occasionally display curiously different chemoselectivities for different reducible substrates, although there is a general list of reactivity against said substrates that applies. The list has carboxylic acids smack bang at the bottom with esters being pretty challenging substrates also. This would perhaps be to do with their poor capacities to dock to the metal surface - important in the hydrog process.
More
VOTE
Methoxide is more basic , As in case of phenoxide the lone pair are in conjugation .
Methoxide is more basic , As in case of phenoxide the lone pair are in conjugation .
More
VOTE
Ok That means We can use both method to reduce .!! Thanks
By the way we can reduce Carboxylic acid to Alcohol by Using LAH but i didn't find anywhere where reduction of Carboxylic acid by Catalytical Hydrogenation can take place..!!
Can Anybody Help me on my another Doubt No one is replying
http://www.chemicalforums.com/index.php?topic=78907.0
Ok That means We can use both method to reduce .!! Thanks
By the way we can reduce Carboxylic acid to Alcohol by Using LAH but i didn't find anywhere where reduction of Carboxylic acid by Catalytical Hydrogenation can take place..!!
Can Anybody Help me on my another Doubt No one is replying
http://www.chemicalforums.com/index.php?topic=78907.0
More
VOTE
Someone please help me on this topic .
Someone please help me on this topic .
More
VOTE
Ohk thats ok if ester having leaving group such as phenoxide (PhO-) or methoxide (OCH3-) they are pretty much good leaving group than Hydroxide (OH-) .
But If you have ester having Higher Substituents like pentoxide (OC5H11-) they are bad Leaving group due to large +I effect .
So I can conclude that We can't replace OH by anything it should be either OMe or OPh ..!! Am i right ?? But as far i know catalytical hydrogenation occurs through radical Mechanism ..!! So I think leaving group ability nothing to do with Hydrogenation .!!!
Can anybody How It get Reduce to Alcohol ??
RCOOR' + H2
First A Pi bond is breaks Radical forms and 2 Hydrogen get inserted but what will happen next ?? Can It Break
Sigma bond ??
Ohk thats ok if ester having leaving group such as phenoxide (PhO-) or methoxide (OCH3-) they are pretty much good leaving group than Hydroxide (OH-) .
But If you have ester having Higher Substituents like pentoxide (OC5H11-) they are bad Leaving group due to large +I effect .
So I can conclude that We can't replace OH by anything it should be either OMe or OPh ..!! Am i right ?? But as far i know catalytical hydrogenation occurs through radical Mechanism ..!! So I think leaving group ability nothing to do with Hydrogenation .!!!
Can anybody How It get Reduce to Alcohol ??
RCOOR' + H2
First A Pi bond is breaks Radical forms and 2 Hydrogen get inserted but what will happen next ?? Can It Break
Sigma bond ??
More
VOTE
But i have same question why we can't use Carboxylic acid ??
Why usually we have to convert carboxylic acid into ester first ??
But i have same question why we can't use Carboxylic acid ??
Why usually we have to convert carboxylic acid into ester first ??
More
VOTE
More
VOTE
Ok So that means both have their own advantages . Can you prefer me any link or book where i can get the information about reducing properties of different reducing agents ??
and what about reactivity order of these metals ??
Pd , Pt , Rh , Ni , Ru
Ok So that means both have their own advantages . Can you prefer me any link or book where i can get the information about reducing properties of different reducing agents ??
and what about reactivity order of these metals ??
Pd , Pt , Rh , Ni , Ru
More
VOTE