Supercritic CO2 as an extraction solvent

[asfd]

Last semester we extracted caffeine from tea with CH2Cl2 and we were told it's possible to do the same thing with liquid CO2. This is interesting but pretty hard to do since you need high pressure/low temp in order to get liquid CO2. My question is: would it be possible to use liquid nitrogen instead of CO2 to do the same thing?

 

[Gokul43201]

I'm pretty sure liquid N2 won't work anywhere near as well as liq. CO2.

The reason the CO2 is used is because it is a great organic solvent, not because it is a cold liquid. The problem of the liquid CO2 can be partially overcome by what is commonly known as CO2 snow. CO2 snow is used with great success in removing organic matter from micro-electronic chips. My lab considered buying this equipment for cleaning the chips we make, but the things are so @#$*^%& expensive ! :grumpy:

For more on this, simply Google "CO2 cleaning".

 

[ravenprp]

Using supercritical CO2 as an extraction solvent is a relatively new and exciting technique in the field of chemistry. It offers several advantages over traditional solvents such as CH2Cl2, including being non-toxic, non-flammable, and environmentally friendly. Additionally, it can be easily removed from the extracted product, making it ideal for food and pharmaceutical industries.

However, as you mentioned, the use of supercritical CO2 does require high pressure and low temperature conditions, which can be challenging to achieve. This may make the process more difficult and time-consuming compared to using traditional solvents.

As for your question about using liquid nitrogen instead of CO2, while both substances share similar properties, they are not interchangeable in this context. Liquid nitrogen is typically used for cryogenic applications and is not capable of reaching the supercritical state required for extraction. Additionally, liquid nitrogen can be dangerous to work with due to its extremely low temperature and potential for causing frostbite.

In conclusion, while using supercritical CO2 as an extraction solvent may require some additional equipment and expertise, it offers many benefits that make it a promising option in the field of chemistry. Exploring alternative solvents, such as liquid nitrogen, may not be a feasible solution in this case.