how we can seprate chloroform and acetone??

[sanichemist]

hi i'm new member!ineed help to seprate aceton and chloroform. most usual method is distilation but i should survey all possibel metod

[CaptainPanic]

Sounds like homework to me. What have you tried so far? Do you have a book about separation methods? Which ones are listed?

[sanichemist]

hi capitain,i'm university student.and i just try to find any thing about this sepration& i must do it in lab, it's a kind of survey to turn back the waste of lab to use it again,is it clear??or it's need more explanation

[Horza2002]

Well acetone mixes with water while chlroform doesn't. Addinf a small amount of water should allow you to seperate them and then dry the acetone again; never tried that so might work.

 

Distillation would be the best way to do it.

 

Are you mixing waste chloroform and acetone together then? Halogenated waste solvents should be kept seperate as it needs different precaution and methods to deal with it

[sanichemist]

u know mixture of acetone and chloroform are result of a physicalchemistry examination,i'v never mixed them togther.it's a waste place ,we want to collect the waste and recycle them and we dont wanna enter the dangerous material into enviorment and it's one of our project.we are doing this undercover a organic chemistry lab,and it's a part of our university.pleasae help me,this project is the firs project of mine and i'm alittle scared.

[Horza2002]

If its a mixture then the best way will be to distil the mixture. Acetone boils at 56oC while chloroform boils at 61oC. Might be a little tricky to keep the temperature at around 58oC but that should work

[sanichemist]

do u believe in there is no way except distillation??? i think cause of both boiling point are near together may be make problem,isn't it??

[pioneer]

The mixture of acetone and chloroform can not be separated fully with simple distillation. The reason is these will form an azeotrope. This is sort of a pinch point after which what was in the pot (higher boiler) now becomes more concentrated in the vapor phases. Below shows the azeotrope pinch point of propanol and water.

 

One trick to break the acetone-chlorform azeotrope is to do an extractive distillation, where you add some water (third component) and then distill.

[mississippichem]

You could distill in high vacuum if you have the equipment and try to get around that nasty azeotrope.

 

Or you could reduce the acetone with [ce] NaBH_4 [/ce] to 2-propanol that boils at ~85 C. Then you could oxidize it back to acetone with pyridinum chlorochromate or chromic acid. You might lose a little acetone to the process but organic redox reactions usually have good yields.

 

Or you could, on the wilder side, react the acetone with ethan-1,2-dithiol to give the cyclic thioacetal, which is easily hydrolyzed off in acidic solution I believe. You could then put the whole mixture down a fairly long [ce] \alpha [/ce]-alumina column, of which chloroform and the thioacetal might achieve good resolution.

 

*note: don't put acetone or 2-propanol on an alumina column unless you have a year of life to waste. I put ethanol on a 2 meter alumina column one time and learned the hard way.

Edited October 6, 2010 by mississippichem

[sanichemist]

wow,that's sounds great.mississippichem, ur opinion is so strange.have u ever done those ideas??

[Horza2002]

While reducing and oxidising the acetone might give you good seperation, its not exactly enviromentally friendly. If you've got a large amount of the mixture to seperate then you're going to be using a large amount of metals to do this reaction. If you're then planning on reusing the solvents for more reaction, you'll have to spend lot of time and money extracting the remaining metal to levels that are acceptable. Not to mention you would then have to dispose of the waste metals properly.

 

Pyridinium chlorochromate is also very toxic and difficult to handel safely on a large scale.

 

If you want to use metals to do it, then you could use a co-oxidant to regenerate the reaction species but that would require using stoichemtric amounts of something else. Hydrogen peroxide is a common one but can react with your solvent to give some rather nasty products.

[mississippichem]

While reducing and oxidising the acetone might give you good seperation, its not exactly enviromentally friendly. If you've got a large amount of the mixture to seperate then you're going to be using a large amount of metals to do this reaction. If you're then planning on reusing the solvents for more reaction, you'll have to spend lot of time and money extracting the remaining metal to levels that are acceptable. Not to mention you would then have to dispose of the waste metals properly.

 

Pyridinium chlorochromate is also very toxic and difficult to handel safely on a large scale.

 

If you want to use metals to do it, then you could use a co-oxidant to regenerate the reaction species but that would require using stoichemtric amounts of something else. Hydrogen peroxide is a common one but can react with your solvent to give some rather nasty products.

 

Yeah Horza, your right. It was late here in the US, and I missed the "environmentally friendly" clause in the OP, sorry. He could try a sephadex, or celite column without even using an oxidant at all though.

 

wow,that's sounds great.mississippichem, ur opinion is so strange.have u ever done those ideas??

 

No, not these in particular, but we used to recycle all solvents in the lab I worked in, more for budget than the environment (we have facilities for that), so the post-doc and myself were often forced to come up with outlandish or creative separation methods. Some didn't work but many did; that's the kind of chemistry they don't put in textbooks , i.e. you don't have this, this, and this that you need. You only have this; make it work! I heard those phrases a lot from the boss who also happened to be a hard-ass, so I was often frightened into scientific creativity.

[sanichemist]

:blink:i'm surprise by ur soggestions .any way, thanks everyone.i'll try some thing u soggested to me and i'll say the result to u!! if u remmember some thing new post it to me, every day i'll check this page.