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Author Topic: Odor of cyclohexane?  (Read 2570 times)

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solyaris

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Odor of cyclohexane?
« on: September 12, 2012, 08:38:04 AM »

Could anyone please tell me how the odor of cyclohexane compares to white spirit / turpentine.
I would like to replace the latter with something less overpowering. My application is painting, rather than chemistry. Wikipedia says:

"Cyclohexane has a distinctive detergent-like odor, reminiscent of cleaning product (in which it is sometimes used)."

I would like to replace it for the turpentine / white spirit I currently use. Is this sensible - purely from a smell perspective. Hopefully there will be many people who have had the chance to use it here.

Sorry for the boring question!
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synthon

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Re: Odor of cyclohexane?
« Reply #1 on: September 12, 2012, 09:31:06 AM »

Don't know for sure, but I'd bet it's much more pleasant than turpentine.  I doubt it will dissolve paint nearly as well though, any more details on the application?
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solyaris

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Re: Odor of cyclohexane?
« Reply #2 on: September 12, 2012, 10:02:21 AM »

Errm... cleaning brushes! :-[
I've never smelled cyclohexane, so I'm looking for someone who has... to tell me whether it has a strong or a weak smell.
I'm glad that we can agree that finding a replacement to turpentine is desirable! I'd just like to be sure that cyclohexane smells "ok" before I order some.

Other hydrocarbons have the same bad odor as white spirit (to varying degrees), so hopefully cyclohexane will be a good replacement.
Of course, if someone knows otherwise then please let me know. Thanks.
(The paints that I use are typically soluble in light petroleum ether).
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curiouscat

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Re: Odor of cyclohexane?
« Reply #3 on: September 12, 2012, 04:31:27 PM »

Why not try a off-the-shelf product like this one? "Odorless Mineral Spirit"; they even list paintbrush cleaning as a target application.

http://www.recochem.com/us/index.php/products/solvents/paint_thinnergeneral_purpose_cleaners/item/odorless_mineral_spirits

Chemically it is "distillates (petroleum), hydrotreated light" for what that's worth; the reported boiling point range will give you some clue as to what's in it: 151 to 205°C

I suspect mainly paraffins. To keep low-odor they have to get rid of the aromatics. 
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solyaris

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Re: Odor of cyclohexane?
« Reply #4 on: September 12, 2012, 09:46:10 PM »

Distillates in that range correspond to heavy naphtha - they remove the sulfur by hydrogenation; hence the "low odor". But it is this "low odor" that I am trying to replace.

It may be easier to just order some for myself, and smell it. With a forum of organic chemists I imagined that someone might be familiar with the smell ???
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Dan

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Re: Odor of cyclohexane?
« Reply #5 on: September 12, 2012, 11:09:45 PM »

Quote
With a forum of organic chemists I imagined that someone might be familiar with the smell

The problem is quantifying the smell though, and remember that chemists work in fume hoods which enormously reduce exposure to solvent vapour. It doesn't have a very unpleasant smell, but it is quite volatile. I would certainly not describe it as "low odor", and would assume "odorless mineral spirit" is much less smelly.

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solyaris

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Re: Odor of cyclohexane?
« Reply #6 on: September 12, 2012, 11:38:13 PM »

Ok, thanks Dan. I'll have to try it for myself, I think.

I would be happy to replace a "detergent" smell for a "turpentine" smell - chances are that I find the latter more disagreeable than most due to daily use!
But a fume cupboard... now that's an idea!

Thanks for the help. ;)
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curiouscat

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Re: Odor of cyclohexane?
« Reply #7 on: September 13, 2012, 01:40:53 AM »

Distillates in that range correspond to heavy naphtha - they remove the sulfur by hydrogenation; hence the "low odor".

Hydro treating reduces both S and aromatics.
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solyaris

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Re: Odor of cyclohexane?
« Reply #8 on: September 13, 2012, 01:59:19 AM »

Interesting. I know that aromatics used to be removed with sulfolane/dimethyl sulfone. Is there some catalyst that hydrogenates both without being poisoned, now?
I used to work for Shell about 20 years ago, but certainly things have moved on in the world of catalysts. Unfortunately I didn't have the chance to smell cyclohexane - my one regret! ;D
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curiouscat

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Re: Odor of cyclohexane?
« Reply #9 on: September 13, 2012, 02:26:12 AM »

Interesting. I know that aromatics used to be removed with sulfolane/dimethyl sulfone. Is there some catalyst that hydrogenates both without being poisoned, now?
I used to work for Shell about 20 years ago, but certainly things have moved on in the world of catalysts.

Well, you might know more about than I do!  I'm looking to get into the refining industry after my PhD / Post-doc right now.,,,,. ;)

But yes, I think the Co-Mo-W catalysts do both. "Brim" sites or some such; had pretty cool looking STM images of the active sites; I think the trick is that they are pre-sulfided. Haldor Topsoe makes some good ones.

The Pd-Pt catalysts also work for aromatic saturation in the presence of S but high cost constrains their commercialization. The literature is very interesting especially the activity synergy of Pt-Pd at a 4:1 composition.

OTOH the latest ULSD specs. are so stringent (~5 ppm S in on-road diesels) that it is almost impossible to get the last bits of S out without doing some aromatic saturation. The S left after reaching 40 ppm levels is almost exclusively the dimethyl-dibenzo-thiophenes (and analogs). The steric shielding of the S part of the molecule prevents access to the S unless partial hydrogenation happens.

At least that's as much of it as I know and understand..

PS. I'm only an engineer so apologies if I messed up any of the details.
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408

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Re: Odor of cyclohexane?
« Reply #10 on: September 13, 2012, 04:51:23 AM »

"a full bodied earthy deliciousness"
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discodermolide

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Re: Odor of cyclohexane?
« Reply #11 on: September 13, 2012, 05:03:11 AM »

"a full bodied earthy deliciousness"

Sounds like you have a nice bottle of wine there!
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solyaris

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Re: Odor of cyclohexane?
« Reply #12 on: September 13, 2012, 07:14:42 AM »

Interesting. I know that aromatics used to be removed with sulfolane/dimethyl sulfone. Is there some catalyst that hydrogenates both without being poisoned, now?
I used to work for Shell about 20 years ago, but certainly things have moved on in the world of catalysts.

Well, you might know more about than I do!  I'm looking to get into the refining industry after my PhD / Post-doc right now.,,,,. ;)

But yes, I think the Co-Mo-W catalysts do both. "Brim" sites or some such; had pretty cool looking STM images of the active sites; I think the trick is that they are pre-sulfided. Haldor Topsoe makes some good ones.

The Pd-Pt catalysts also work for aromatic saturation in the presence of S but high cost constrains their commercialization. The literature is very interesting especially the activity synergy of Pt-Pd at a 4:1 composition.

OTOH the latest ULSD specs. are so stringent (~5 ppm S in on-road diesels) that it is almost impossible to get the last bits of S out without doing some aromatic saturation. The S left after reaching 40 ppm levels is almost exclusively the dimethyl-dibenzo-thiophenes (and analogs). The steric shielding of the S part of the molecule prevents access to the S unless partial hydrogenation happens.

At least that's as much of it as I know and understand..

PS. I'm only an engineer so apologies if I messed up any of the details.
Thanks for the info.... that's some good knowledge! I assumed that aromatic hydrogenation was not worth the bother (price-wise). but necessity is the mother of invention; what-with all the regulations and so on - I suppose - Good luck with your career plans :)

Edit:
re: "The literature is very interesting especially the activity synergy of Pt-Pd at a 4:1 composition. "
I've not read about this - if it's no bother could you provide further details? - I work a lot with homogenous Ru catalysts, so it is an area I'm interested in. No-need to go out of your way to find it if not convenient, though.
« Last Edit: September 13, 2012, 07:30:13 AM by solyaris »
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curiouscat

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Re: Odor of cyclohexane?
« Reply #13 on: September 13, 2012, 06:58:13 PM »


Edit:
re: "The literature is very interesting especially the activity synergy of Pt-Pd at a 4:1 composition. "
I've not read about this - if it's no bother could you provide further details? - I work a lot with homogenous Ru catalysts, so it is an area I'm interested in. No-need to go out of your way to find it if not convenient, though.

Just sent you a PM about this. I do know some good papers on this.
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Enthalpy

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Re: Odor of cyclohexane?
« Reply #14 on: September 17, 2012, 04:56:36 AM »

From MSDS: cyclohexane is said to have a faint agreable gasoline-like odour, which sound contradictory to my ears...
It seems globally safer than turpentine, except that its flash point is -18°C instead of being above room temperature.
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