Why is dichloromethane a good organic solvent?

[birdstudyphys]

I was working on my chem lab, this question occurred to me. Water and dichloromethane are both polar molecule. However, dichloromethane is able to mix with alcohols much better than water. Is there a polarity difference that caused the miscibility to be different?

 

[lightarrow]

I was working on my chem lab, this question occurred to me. Water and dichloromethane are both polar molecule. However, dichloromethane is able to mix with alcohols much better than water. Is there a polarity difference that caused the miscibility to be different?

Of course you are talking about higher weight alcohols, not CH3OH or C2H5OH, which are completely miscible with water. However CH2Cl2 is not as polar as water so it mix better than water with organic compounds.

 

[birdstudyphys]

Yeh. CH2Cl2 is barely polar actually since C-Cl has deltaEN=0.5 where C-H gives a 0.4.
Much less polar than water for sure.. Well that explains it. Thanks. I was totally misled by my weird thinking... Egrrr.

 

[gravenewworld]

DCM is also an excellent solvent for convenient reasons like being more dense than water so it will be on the bottom in a separatory funnel if you do an aqueous workup and it is also easy to evaporate.

 

[y2j_molino]

However it is toxic, though the least of the chlorinated ethers. CH2Cl2 is partially miscible in water (it is not polar) , but its diffusivity in water is higher that water in CH2Cl2. IF working with hydrophobic polymers, it tends to be in general a good solvent. Specially for PLA.