FormicAcidAnimal
Harmless
Posts: 9
Registered: 29-10-2015
Member Is Offline
Mood: No Mood
|
|
Question about tartaric acid and it's use for resolution of racemic amines
Hi there!
In this text (https://www.erowid.org/archive/rhodium/chemistry/amphetamine...) it says:
| Quote: |
....And in those methods, d-tartaric acid is used to obtain the dextro amine and l-tartaric acid to prepare the laevo amine. However while those
processes are operable chemically, they have serious disadvantages, particularly with regard to the separation of l-amphetamine by means of d-tartaric
acid, in that while d-tartaric acid is readily available and comparatively cheap, l-tartaric acid at the present time is both difficult to
obtain and expensive in pure form (d tartaric acid comes from fruit, l-tartaric acid is 'unnatural').... |
Though according to Wikipedia the usual E 334 tartaric acid used in foods actually is the L-form!?
I'm a bit confused - though I've been always a noob in stereochemistry ^^
Can someone explain it to me, please?
|
|
|
karlos³
International Hazard
Posts: 1520
Registered: 10-1-2011
Location: yes!
Member Is Offline
Mood: oxazolidinic 8)
|
|
That is probably a mistake, as it is the other way around.
l-tartaric acid is the natural one, like it is in nearly every natural chemical with chirality. The d-form is mostly unnatural, that is also true for
most amino acids.
Another chemical used to separate enantiomers is n-acetyl leucine.
Both isomers are readily available.
|
|
|
Nicodem
Super Moderator
Posts: 4230
Registered: 28-12-2004
Member Is Offline
Mood: No Mood
|
|
Quote: Originally posted by FormicAcidAnimal  | Though according to Wikipedia the usual E 334 tartaric acid used in foods actually is the L-form!?
I'm a bit confused - though I've been always a noob in stereochemistry ^^
Can someone explain it to me, please?
|
d-tartaric acid = L-tartaric acid = L-(+)-tartaric acid (is the natural stereoisomer)
l-tartaric acid = D-tartaric acid = D-(-)-tartaric acid
You don't need to know anything about stereochemistry. All it takes is about 15 seconds of googling.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
|
|
|
Syntropymancer
Harmless
Posts: 5
Registered: 14-12-2015
Member Is Offline
Mood: No Mood
|
|
| Quote: Originally posted by Nicodem | | Quote: Originally posted by FormicAcidAnimal | Though according to Wikipedia the usual E 334 tartaric acid used in foods actually is the L-form!?
I'm a bit confused - though I've been always a noob in stereochemistry ^^
Can someone explain it to me, please?
|
d-tartaric acid = L-tartaric acid = L-(+)-tartaric acid (is the natural stereoisomer)
l-tartaric acid = D-tartaric acid = D-(-)-tartaric acid
You don't need to know anything about stereochemistry. All it takes is about 15 seconds of googling. |
Yeah, you can thank the confusing nomenclature that came out of the early understanding and work done on the chirality of molecules. (+) and (-), also
d- and l- were to designate optical activity, that is, what direction they rotate in a polarized plane.
D- and L-, are unrelated to d- and l- or (+) and (-), as they are based on configuration to a reference molecule, glyceraldehyde, since most chiral
molecules studied at the time were similar, amino acids.
R- and S- are used today, a system based on configuration system by substituent priority, so it does not require a reference molecule.
(also found using google)
|
|
|
chemrox
International Hazard
Posts: 2961
Registered: 18-1-2007
Location: UTM
Member Is Offline
Mood: LaGrangian
|
|
Did anyone else get lost here? I thought D- and d- were the same and related to R & S at least most of the time. Anyway if someone could expand a
little on the D vs d nomenclature as relates to polaremitry I'd appreciate it.
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
|
|
|
byko3y
National Hazard
Posts: 721
Registered: 16-3-2015
Member Is Offline
Mood: dooM
|
|
https://en.wikipedia.org/wiki/Chirality_(chemistry)
Different nomenclatures reflect different properties of a substance. An item can be cold and soft, although another item can be warm and soft.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
