Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: sharbeldam on January 25, 2021, 01:31:44 PM
-
Hello
It’s written in my book that they use RR tartaric acid to react with the racemic mixture of carvone to give two diastereoisomers, it’s a way to split the two enantiomers of carvone, does anyone have a source for this reaction please?
-
CHECK HERE
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6214632/#!po=18.5345
Then scheme 8
-
Hello
It’s written in my book that they use RR tartaric acid to react with the racemic mixture of carvone to give two diastereoisomers, it’s a way to split the two enantiomers of carvone, does anyone have a source for this reaction please?
And how can racemic ketones be separated into enantiomers?
-
Thank you chen but i was kind of looking for a different reaction, Perhaps a simpler one to separate them.
AWK, i really dont know , thought about it a lot , like i thought of many reactions that can happen between carboxylic acid of the tartaric acid and the ketone (like making a amine from the ketone and then producing amide after the reaction) but how would that help me separate them, it doesnt explain it at all, it just says they use tartaric acid to separate these two enantiomers.
-
Sharbeldam, do you want the reaction to be reversible?
-
I'm a pharmacist that studies chemistry in theory, I'm not a chemist and I'm not doing it in a lab, I just like knowing reactions and how they happen, in the book it says ' It is a very known method of using R,R tartaric acid to separate racemic mixture of Carvone into two diastereomers ' and I was just wondering how would that happen and how come it is very known if I cant find it online quickly haha
-
My point was that amide formation is not easily reversed, but what one would want in this case is something that can be reversed (think protecting group chemistry). With respect to tartaric acid, you have two kinds of functional groups.
-
Thank you chen but i was kind of looking for a different reaction, Perhaps a simpler one to separate them.
AWK, i really dont know , thought about it a lot , like i thought of many reactions that can happen between carboxylic acid of the tartaric acid and the ketone (like making a amine from the ketone and then producing amide after the reaction) but how would that help me separate them, it doesnt explain it at all, it just says they use tartaric acid to separate these two enantiomers.
Both carvone enantiomers occur in different plant raw materials. Only pure enantiomers are available for sale. There is no point in creating a racemate artificially and then breaking it apart.
The optically active tartaric acid is used primarily for the separation of amine enantiomers. You are probably using the wrong manual, because a good manual sketches a method and doesn't say "It is a very known method" only.
-
My point was that amide formation is not easily reversed, but what one would want in this case is something that can be reversed (think protecting group chemistry). With respect to tartaric acid, you have two kinds of functional groups.
Im thinking protecting group chemistry, but i still dont get the logic on how would that help me seperate them, lets say i add an OH group instead of the double bond on the chiral carbon (anti-mark) and then use pcc to get aldehyde and then add protecting group with some sort of diol, both enantiomers would react, and then how would they be separated?
the book says ' after they react with tartaric acid we get two diastereoisomers that can be separated via percipitation and other methods '
-
How to make an amine from a ketone, but the amine that is easily converted back into a ketone (i.e. the reaction is reversible).
-
i could react it with a primary amine -> that gives me imine and then i could do reduction and then i get amine, but they both would react the same way and then? how would they be separated? thanks for being patient
-
Have you heard of enamines?
-
like reacting them with secondary amine to get enamines first?
-
For the crystallization of diastereomeric salts, a suitable tartaric acid derivative (most often dibenzoyl tartaric acid) and a suitable solvent or solvent mixture must be found. This is done by trial and error.
But nowadays, racemic mixtures are most often separated by chromatography using chiral stationary phases.
-
Alcohols can react with ketones, but I am not sure what was done in this particular instance.
-
I think you would get 1,4-addition if you mix the ketone with amine.
-
Can someone just give me a reaction that I can do on carvone that once I react it with tartaric acid it gives two diastereomers? I’m so confused now
-
Free tartaric acid might or might not work, but a diester might be better. I would make the ketal, using the ketone group of carvone. After separation, I would hydrolyze.
-
I also thought of a ketal, mayby its complicated when you have the isopropylene group, this group can also react with alcohols under acidic conditions. I think you can do this without acid if you make a stannane of the tartaric ester. Then the question is, will these two diastereomeres separate in a good way? Maybe by crystallisation its possible to separate them, on silica-gel its less likely.
-
By saying ketal do you guys mean adding a diol or using the diol of the tartaric acid? Cause according to the book a modification need to happen on the carvone before reacting with the tartaric acid.
-
Then its probably wrong to make a ketal.
-
You can reduce carvone to the alcohol and make a tartaric ester, separate, hydrolyze and oxidize. Not very easy though.
In this link you can se the reduction;
Edit; This is a bad idea, the two enatiomeres of carvone will create twoo different alcohols.
https://en.wikipedia.org/wiki/Carvone
-
Maybe a enamine is the only way. The methyl group might hinder 1,4-addition.
-
By saying ketal do you guys mean adding a diol or using the diol of the tartaric acid? Cause according to the book a modification need to happen on the carvone before reacting with the tartaric acid.
Do I understand correctly that the book does not specify the modification? Can you quote what they say?
-
Rolnor thank you!
Babock, i would have put the source but it is not in english, it just says there is a modification reaction (not specified) and then after it is modified it reacts with tartaric acid to produce 2 diastereoisomers that can be separated, perhaps what rolnor said is what they mean.
you guys all helped me a lot!
-
It may not even be a bond formation. but just cocrystallisation of carvone and the enantiopure acid
-
Sharbeldam says it should be some kind of change in the carvone molecule.
-
Rolnor thank you!
Babock, i would have put the source but it is not in english, it just says there is a modification reaction (not specified) and then after it is modified it reacts with tartaric acid to produce 2 diastereoisomers that can be separated, perhaps what rolnor said is what they mean.
you guys all helped me a lot!
This is very important information that had to be provided at the very beginning. Due to the lack of this information, a few people wasted their time unnecessarily. You've been using this forum long enough to put your questions right!
-
Sorry I wasn't clear in my original post, the only reason for that was that the book mentioned it's a very known method, so I believed that and thought people would just know what I'm talking about. I did imply in the first page that I needed to make something from carvone to react it with the acid, but either way I apologize AWK and thanks!