[c.addle]

Hi! Ive got a task to design a chemical production of 2,6-diisopropylnaphthalene at university. I got to the point Ive got a mixture of 2,7 and 2,6 isomers and now I have to separate them. Probably this way works: selective adsorption of 2,6 in zeolites, then desorption using toluene. Im ok with this, but whats next? What is the easiest way to separate 2,6 isomer from toluene and how to recover toluene? Im not looking for the best way for the production, just for the easiest possible way. Flowchart would be the best way to explain.

Thanks

[Enthalpy]

Hi c.addle, welcome here!

More for my personal information:

I expect the 2,6- and 2,7- isomers to have quite different melting points. Would that be a way to separate them?

Toluene is much more volatile than DIPN. Could it be evaporated?

[Arkcon]

Can you show us your whole plan, showing us the flowchart that you need, as drawn by yourself?  Maybe, the best way is to avoid production of the impurity.

[c.addle]

so this is what ive done, I went with crystallization instead of adsorption/desorption. Impurities are alright, professor told us to choose something like 95% purity to make it easier. He also approved to put crystallization and filtration in one step, to make it easier. So now I need to make 140 kg/h of pure 2,6-DIPN. No idea how to start. How could I balance the crystallization if I know nothing about it? Just temperature 0°C. Nothing more...

the patent says: About 100 g of the isomeric mixture was mixed with about 30 g of n-heptane and the mixture was cooled at 0° C for crystallization. About 25 g of the 2,6-DIPN was obtained as crystals with a purity of 97.9 wt %.

I could apply these number on my case, but professor will ask how I got these numbers and I cant just say I multiplied it

[thelastone]

so this is what ive done, I went with crystallization instead of adsorption/desorption. Impurities are alright, professor told us to choose something like 95% purity to make it easier. He also approved to put crystallization and filtration in one step, to make it easier. So now I need to make 140 kg/h of pure 2,6-DIPN. No idea how to start. How could I balance the crystallization if I know nothing about it? Just temperature 0°C. Nothing more...

First of all I have no idea about this process, but I'm going to give my opinion.

You're probably dealing with a supersaturated solution, one that has a high temperature, and therefore has a high solubility product, a mass that is dilluted. Then since you're cooling this solution to 0ºC you're lowering the Kps. So maybe the mass of the crystalls is the variation of this two values? (Kps_hightemp-Kps_0ºC?)

[c.addle]

Sounds good but I dont have any informations about solubility of 2,6-dipn in heptane..

[Enthalpy]

2,6-dipn melts at +69°C
2,7-dipn melts at -3°C
hence "can be isolated using crystallization method", citing patent CN 101130478 B
http://www.google.tl/patents/CN101130478B?cl=en

About the toluene option:
Toluene boils at +111°C under 1atm
dipn boils at +280°C, should be under 1atm

[thelastone]

2,6-dipn melts at +69°C
2,7-dipn melts at -3°C
hence "can be isolated using crystallization method", citing patent CN 101130478 B
http://www.google.tl/patents/CN101130478B?cl=en

About the toluene option:
Toluene boils at +111°C under 1atm
dipn boils at +280°C, should be under 1atm

I think he is asking a way to demonstrate the values he's got from other patents.

Sounds good but I dont have any informations about solubility of 2,6-dipn in heptane..

Back in the days when I studied, my university had a handbook of solvents, but also I seem to recall that you can "aproximate" the solubility product with the following equation:

Ksp = e^[-ΔG/(RT)]

Check for this book also : http://www.sciencedirect.com/science/book/9780750670128


But I'm only brainstorming, you should head directly to your teacher and ask his/her opinion.

[c.addle]

Teacher told me to approximate too, but still have no idea how..i just know the solubility in water is very low. Theres nothing about solubility in books.

Im going to check that book as soon as Im on my computer to have an access to it. Thanks