n-Heptane equal/superior to naphtha?

[AluminumFoilRobots]

I was reading over on the thread in collaborative research about a potentially hazardous new additive in some brands of naphtha some folks saying that n-heptane could be be used interchangeably with naphtha and may be indeed be a superior solvent for Spice, especially in the light of this whole naphtha additive issue. I was just wondering what folks thought about that and if there is a any growing consensus on the matter. I don't have any experience with the stuff myself and I need to learn more about it. All I know is people like to use it for re-crystallization.

Like for instance you could do your pulls in an A/B tek with just heptane? Would you have to FASA/I/W or whatever?

Sup with n-heptane?

 

[downwardsfromzero]

Naphtha is an aliphatic hydrocarbon solvent. n-Heptane is an aliphatic hydrocarbon solvent. Naphtha is a mixture of compounds. n-Heptane is a single, pure compound. Each of them will have their merits but the behaviour of n-Heptane will of course be more predictable.

The solubility in n-Heptane of any given extracted material will always be the same at a particular temperature. The boiling point of n-Heptane is always the same at a particular pressure. These factors could be considered advantages. The price and availability of n-Heptane relative to naphtha could be considered disadvantages.

Heptane could be used in exactly the same way as naphtha for pulls from an A/B extraction. It will freeze precipitate, as evidenced by the use of its temperature/solubility gradient when used for recrystallisations. It's entirely likely that the problem of fumaric acid precipitating, as when attempting a FASA method with naphtha, would also apply. Limited testing suggests that spiking the naphtha with a bit of acetone before adding the FASA helps to prevent this. Presumably this would also apply to n-Heptane, but I don't know as I've never tried it nor heard any reports of this. It seems very likely though.

If you do have a load of n-Heptane, it would be great if you could try this out. But, understandably, you might not want to if you can just freeze precipitate - although you might get a tiny bit more product out of the solvent with FASX.

 

[AluminumFoilRobots]

Word. I'll have to get some to experiment with next time.

 

[blue.magic]

n-heptane is reportedly more selective for DMT than naphtha.

BUT I think the DMT solubility is lower for heptane at room temperature. So unless you keep the heptane heated, it may not perform as well as naphtha.

For me, it works great for final purification and recrystallization as dmt precipitates very quickly from it.