O/T Organic Solvents

[candle25]

I am going to be doing an extraction soon and I need to use an aprotic solvent first to remove the nonpolar things, followed by a protic solvent to extract the polar thing that I'm interested in. For the aprotic I'm thinking of using Naptha which contains petrolium ether. I don't want to pay $50 for 500ml of USP Ether. For the protic solvent I'm thinking of using heet (MeOH). The crude product will be in the MeOH and will be evaporated out. I'm not sure I can wash it so does anyone see a problem with using the solvents that I've mentioned?

The acute toxicity of methanol by ingestion, inhalation, and skin contact is low. Ingestion of methanol or inhalation of high concentrations can produce headache, drowsiness, blurred vision, nausea, vomiting, blindness, and death. In humans, 60 to 250 mL is reported to be a lethal dose. Prolonged or repeated skin contact can cause irritation and inflammation; methanol can be absorbed through the skin in toxic amounts. Contact of methanol with the eyes can cause irritation and burns. Methanol is not considered to have adequate warning properties.

Methanol has not been found to be carcinogenic in humans. Information available is insufficient to characterize the reproductive hazard presented by methanol. In animal tests, the compound produced developmental effects only at levels that were maternally toxic; hence, it is not considered to be a highly significant hazard to the fetus. Tests in bacterial or mammalian cell cultures demonstrate no mutagenic activity.

 

[candle25]

OK. I can't find Naptha anywhere. What I need is Petrolium Ether CAS#8030-30-6. Anyone know where I can get it?

 

[jboogie]

Naptha is available from any hardware store, check in the paint section near the other solvents (turps, paint thinner,etc). If for some reason that fails (but I'm sure they have it at Lowes/HomeDepot), you can also use Zippo brand lighter fluid.

To be honest, I'm not sure what the hell you're extracting. Most extractions I've ever done the goodies end up in the NP solvent and you evap that off.

In any situation where you're evaporating something, you want to do a test evap by putting a sizeable amount of your solvent in a pyrex dish and place it under a fan to check for any inpurities that aren't going to evaporate.

You want to know what extra crap is in your OTC solvents before you consume the final product.

 

[candle25]

You seem to heve the right idea bro, thanks. In this case the product will be in the polar MeOH. I will be using a 2 step extraction to first remove the usless garbage, followed by a second extraction to get what I need.

I might try the Naptha if I can find it today. I saw some reseach that showed that Naptha, Zippo, & Coleman all left some oily residue after evaporation. The chemist believed that it wasn't harful, so I'll just have to decide when I do my own research.

I'm only taking my purity to the crude stage as it isn't that important for this compound. I could treat it with a dilute HCl followed by NaOH which would precip out a nice white crystal, but the brownish/yellow "gum" will be fine.

BTW, welcome to AM jboogie. Do you have any formal chemistry training? Just curious.

 

[jboogie]

I'm only taking my purity to the crude stage as it isn't that important for this compound. I could treat it with a dilute HCl followed by NaOH which would precip out a nice white crystal, but the brownish/yellow "gum" will be fine.

BTW, welcome to AM jboogie. Do you have any formal chemistry training? Just curious.

No formal chemistry, 2 years in highschool and two semesters in college, I'm technically a computer guy. I've done a bunch of AB extractions on plant material post-school for "research purposes", shall we say, and I've had to deal with finding clean naptha before.

As for your research finding that others left a residue, I can say that the same brand of naptha in the same packaging from two different geographic areas will often times contain a mix of different solvents. Sometimes you have to ignore what people say on message boards about a particular brand and just try to evap several kinds for yourself. ...and then stock up on the clean one

 

[candle25]

Great. I'm quite sure we are thinking along the same lines...lol. I am indeed doing a plant extraction. I'll post back later and let you know how it goes.