[Arnfinn]

Hi.My problem is that i need to explain how can seperate those two substances on the lab with a method called extraction.I also need to write full reaction-equations when expalining it.

the strucural formula for codeine can be found at :
http://opioids.com/codeine/codeine.jpg

and para-dimetoksibenzene, has formula (C=8,H=10 and O=2), it is a benzen molecule, with two OCH3 groups bounded to it.One pointing up and the other down.(with a line from the benzene molecule to the OCH3 groups pointing up and down).

Can anyone help me to explain how i can perferm this seperation? I did a previous lab-exercise, where i seperated para-dimetoksibenzene and benzoic acid.Then i did the following :

1.Weight out 2,00g benzoic acid and 1,00g para-dimetoksibenzene.and placed it in a Erlenmeyer flask.
2.Solved them in 30mL diethyl ether.
3.Placed it in a 100mL separating funnel,and extracted with 2x20mL NaOH solution.
4.took the water phase into a 100mL beaker, by opening the seperating funnel.Then added HCL acid to get precipitation
of the benzoic acid.Then it was possible to filter it out by using a funnel and filtering paper.

Can add Diethyl eter as a solvent of Para-dimetoksi benzene in this case?

NaOH were added to perform reaction with the benzoic acid,to form water. Therefore Na(+)(aq) benzoate(aq)( the negative ion of benzoic acid) will be ions in the water phase, and NaOH doesnt affect the dimetoksibenzene which be solved in the topmost ether phase in the seperating funnel.

But in this case iam not sure if this prcedure will work.As far as I can see, Codeine is a pretty unpolar molecule, since it has many benzene rings with alot of C-atoms. But it also has a OH broup, and N-atom (which i think is a tertiary amine group, isnt it?). And it also as a O-atom bounded between two of the benzene rings, which indicates that it has some properties of an Ether?Am I correct?

What I have learned so far is that usually alkaline(basic) are beeing added to neutralize acidic groups on molecule to create water.Thats why NaOH was added on the example above. But Codeine is different.The N-atom has two free electron pairs.It can act as a weak base? But can anything happend to the OH group? Ive heard that phenols are weak acids.Why is that? Can this OH group act as a weak acid?Or can it act as a base?

Should i add a strong acid or a strong base to this solution to create water phase?Is it possible to get precipitation of Codeine in the water phase,as I did for benzoic acid?


I really appreciate all the help i cant get    

[Arnfinn]

it really hurry for me to get this question answered....cant anyone help please?
atleast, do anyone know any solvents for codeine?

[CT101]

I think people might be confused as to why you are mixing chemicals just to separate them again. Also, you mispell a lot of words in your first post, which makes it really difficult to understand what you're trying to say.

That said, I think you can do what you did before, only add phosphoric acid to the mix instead of NaOH. I think that will convert the codeine into a phosphate ester (which is how it is administered as medicine anyway) at the hydroxyl group on the codeine, and water will be a byproduct. Codine phosphate is very water soluble, so I think you can go from there. Sulfuric acid works too to form codeine sulfate. Para dimethoxybenzene is a pretty stable molecule, so I would derivitize the codeine.

As for phenols, yes they are weak acids. The delocalized sp2 carbons in phenol weaken the OH bond.

Good luck!

[Fry]

The phosphoric acid protonates the tertiary amine.. this gives the amine a positive charge and the negatively charged conjugate base hangs around. Its a salt, not an ester.

[sjb]

I think people might be confused as to why you are mixing chemicals just to separate them again. Also, you mispell a lot of words in your first post, which makes it really difficult to understand what you're trying to say.

That said, I think you can do what you did before, only add phosphoric acid to the mix instead of NaOH. I think that will convert the codeine into a phosphate ester (which is how it is administered as medicine anyway) at the hydroxyl group on the codeine, and water will be a byproduct. Codine phosphate is very water soluble, so I think you can go from there. Sulfuric acid works too to form codeine sulfate. Para dimethoxybenzene is a pretty stable molecule, so I would derivitize the codeine.

I think you can probably get away with HCl, just to form the ammonium salt, as p-dimethoxybenzene has been shown not to react with that in previous experiments by the OP. I'd be wary of covalent modification, as these in my experience tend to be very annoying to take off again when you need to re-generate your original molecule.

As for phenols, yes they are weak acids. The delocalized sp2 carbons in phenol weaken the OH bond.

Good luck!

True enough, but be careful, as the free hydroxyl group in Codeine is not a phenol

S

[CT101]

I know the OH group in codeine is not a phenol, sjb. But I got the impression the topic creator knew it as well . To me it sounded like thought he could apply the same reasoning to the hydroxyl in codeine (because of the cyclohexene ring).

As for the phosphoric acid....I forgot about the tertiary amine at the top...oopps....but I still stand by what I said about converting the hydroxyl group into a phosphate ester...it doesn't just work for nucleotide synthesis. However, I don't think the phosphorylation of codeine is as complicated as it is when synthesizing nucleotides.  It's just another way of doing it

[sjb]

I know the OH group in codeine is not a phenol, sjb. But I got the impression the topic creator knew it as well . To me it sounded like thought he could apply the same reasoning to the hydroxyl in codeine (because of the cyclohexene ring).

OK, I've re-read the original post and I can see where you're coming from, initially I read it and thought perhaps Arnfinn thought it was. No problem

As for the phosphoric acid....I forgot about the tertiary amine at the top...oopps....but I still stand by what I said about converting the hydroxyl group into a phosphate ester...it doesn't just work for nucleotide synthesis. However, I don't think the phosphorylation of codeine is as complicated as it is when synthesizing nucleotides.  It's just another way of doing it

Absolutely. I have no real scientific problem with what you've proposed. Just wasn't my first choice, that's all.

Indeed this may be the best way to approach the problem if you have a weakly zwitterionic intermediate, like a phenolic tertiary amine - change the pKa of one of the protons so you can more easily effect phase switches with acid and base as appropriate.

S