ether solubility

[akimhaneul]

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Why is it that cyclic ethers are soluble in water whereas aliphatic ethers like ethylmethyl ether are not?


Also, shouldn't all ethers in general be a polar molecule because of lone pairs on oxygen?

 

[Cawolf]

A small aliphatic ether, like diethyl ether, is slightly soluble in water. It has limited solubility, but as you said, is slightly polar. As you get larger aliphatic ethers, the solubility quickly drops off.

A cyclic ether like THF is fully miscible in water. This is a special case for ethers as the ring form "exposes" the lone pairs on the oxygen to a greater extent, allowing it to freely accept hydrogen bonds in water.