aaroniser
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store bought solvents
Hi all,
I have a question relating to the purity/toxicity of some store-bought solvents. I am trying to extract the essential oil of a large quantity of
thyme I grew in my garden this summer. I soaked the plants for about a week in a gallon of acetone paint remover I picked up at Wal-Mart, then
evaporated it down to a dark, fragrant syrup.
However, I'd like to further purify this sludge, as the acetone seems to have picked up just about everything. I was planning on doing a
solvent/solvent extraction with either water/ethyl acetate or water/hexane. I couldn't find any pure ethyl acetate, but I could pick up a gallon of
hexane camping-stove fuel for ~$5.
However, I'm worried about possible toxins or carcinogens that might remain after this hexane is evaporated. So my question: Would this hexane be
resonable safe? If not, are there any other cheap, widely available non-polar solvents that would work well?
Thanks!
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BromicAcid
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It's amazing the amount of crap in those OTC solvents. They have no incentive to actually make them pure in the least since their purpose is of
course for a general solvent not for a reagent grade material. Hence your best bet is going to be a fractional distillation first, this should give
something of a reasonable purity. I once distilled 500 ml of store bought xylene, I was left with 75 ml of yellow high boilers in my distillation
flask that didn't even attempt to come over at 15C over the boiling point of xylene. I have heard stories from several other members as well as
through a thread around here somewhere about similar experiences with pretty much all the other solvents available OTC.
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Eclectic
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You might try an isopropanol/salt water extraction. That should get rid of most of the sugars, proteins, and salts. Isopropanol is a really good
extractant for plant materials, with salt added afterward to remove most of the water soluble gunk and excess water. Methanol/VM&P solvent is
good for getting rid of fats and hydrocarbon terpines.
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chemrox
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I haven't had any difficulties with store bought solvents. I've used xylenes in a can to dehydrate eaction mixtures and I use store bought acetone to
dry glass all the time. For extracting plants I would at least use a technical grade chemical company sovent. I don't like acetone for extracting
plants. I would consider the ethanol of commerce whihc is denatured with MeOH. But for thyme oil I would steam distill. beware though. The
extraction vessel I made for my steam still was aluminum and the seal wasn't good. I set out to make thyme oil and ended up making esters and soap.
the steam leaked out before the oil was mobilized enough to reach the condenser. Acids in the thyme reacted with aluminum. In summary there were
three things wrong with my setup: The extractor was made of aluminum, the seal was no good and the volume was too big compared with the steam source.
I'm building a new extractor out of a stainless pressure cooker. The condenser is a copper coil as before but I've jacketed the coil with an
aluminum stock pot that will contain cold water and ice while the process is underway.
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undead_alchemist
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I have had pretty good results with OTC solvents from Recochem.
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Antwain
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Many OTC solvents are ok, but you should look for the following:
1) That the solvent is sold by a chemical name instead of 'product' name
2) That it has an 'assay' (of sorts) on the side such as "ethanol 95% v/v"
and obviously, if the assay is bad then the product is NOT pure.
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undead_alchemist
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| Quote: | Originally posted by Antwain
Many OTC solvents are ok, but you should look for the following:
1) That the solvent is sold by a chemical name instead of 'product' name
2) That it has an 'assay' (of sorts) on the side such as "ethanol 95% v/v"
and obviously, if the assay is bad then the product is NOT pure. |
Very true
From what I have seen on the labels from Recochem, they do
list the chemical name, and or sold under the chemical name as well.
A lot of their solvents are 99.5%
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DerAlte
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Might be of interest:
http://www.iupac.org/publications/pac/1986/pdf/5811x1535.pdf
(re acetone.)
Der Alte
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