[minasouliman]

Hi, for my intro organic chem. lab, we're given a soil sample with 2 inorganic and 2 organic compounds in it. We'v qualitatively determined that the inorganics are CoSO4 and NiCl2, and the organics are m-nitroaniline and Camphor. We've also already done the quantitative analysis for the inorganics using Beer's law. The next step is where we are at loss. We need to quantitatively determine the amount of organics in our soil, and I just wanted to make sure that the schema that I have in my head will work out in the lab tomorrow. I was thinking that we can dissolve the soil in ethyl acetate, do an acid extraction with 6M HCl to get the aniline out, then we can evaporate the ethyl acetate layer off and weight the product and do the spectroscopy that we need on that. Then for the aqueous layer of the extraction, we can neutralize with NaOH and then re-extract out into ethyl acetate, evaporate, and go on from there.

My questions are as follows: Does this schema make sense? Are our choices of solvents ideal for this separation and analysis? As in, will we have non-negligible cross-contamination between the two?

Also, we need to purify our product in order to submit it for mass-spec analysis, would sublimation be a good technique in this situation? Or is there a better technique, preferably non-time-consuming.

[Dan]

Hi, for my intro organic chem. lab, we're given a soil sample with 2 inorganic and 2 organic compounds in it. We'v qualitatively determined that the inorganics are CoSO4 and NiCl2, and the organics are m-nitroaniline and Camphor. We've also already done the quantitative analysis for the inorganics using Beer's law. The next step is where we are at loss. We need to quantitatively determine the amount of organics in our soil, and I just wanted to make sure that the schema that I have in my head will work out in the lab tomorrow. I was thinking that we can dissolve the soil in ethyl acetate, do an acid extraction with 6M HCl to get the aniline out, then we can evaporate the ethyl acetate layer off and weight the product and do the spectroscopy that we need on that. Then for the aqueous layer of the extraction, we can neutralize with NaOH and then re-extract out into ethyl acetate, evaporate, and go on from there.

Right idea. A couple of things:

1. You could remove the inorganics at the start (can you suggest how?). Not strictly necessary, but reduces the likelihood of inorganic contamination.

2. 6 M HCl is like using a sledgehammer to knock in a drawing pin. It'll work but it's over the top. 1 M HCl should be sufficient and is safer for you to handle.

Also, we need to purify our product in order to submit it for mass-spec analysis, would sublimation be a good technique in this situation? Or is there a better technique, preferably non-time-consuming.

Yeah, I guess you could sublime it. That wouldn't be my first choice, what other methods do you know for the purification of crystalline solids?