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I want to perform a reaction which needs the temperature to be maintained between 400–430 °C. Since it's the only practical solution, I opted for a heated bath.

I'm looking for a hydrocarbon fraction/blend with the boiling point in this range, however, I keep finding conflicting information. If anyone knows such a hydrocarbon product please, let me know.

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    $\begingroup$ Those temperatures are well above the flash point of any hydrocarbon I can find, and above the autoignition point of many. Might you be able to get by with a sand bath or tightly-regulated mantle instead? $\endgroup$
    – jeffB
    May 18, 2019 at 0:48
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    $\begingroup$ The point of a heated bath is that the temperature, given sufficient heating, will be exactly the boiling point of the medium. Sand bath would offer no control over the temperature. $\endgroup$
    – Francis L.
    May 18, 2019 at 1:53
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    $\begingroup$ Also, to rig such a mantle on ones own would be no small feat. Not to mention being able to afford one. $\endgroup$
    – Francis L.
    May 18, 2019 at 2:07
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    $\begingroup$ Keep in mind there is also a variety of molten salt baths; however, you'll need a thermocouple and protect the glassware as the majority of molten salts would etch the glass. $\endgroup$
    – andselisk ♦
    May 18, 2019 at 6:37
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    $\begingroup$ What's wrong with carrying out your reaction in a furnace? $\endgroup$
    – svavil
    May 18, 2019 at 7:37

2 Answers 2

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If it doesn't specifically need to be a hydrocarbon, zinc metal melts at 419.5 °C. Could you do an "ice bath" of zinc chunks in molten zinc, maintaining the melt right at its melting point?

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  • $\begingroup$ I have to say this is an interesting idea. I'll give it a good thought. $\endgroup$
    – Francis L.
    May 18, 2019 at 2:15
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    $\begingroup$ In fact, if it works it will be a superior solution, since I won't lose the zinc to the atmosphere the same way I would lose the liquid. I'll let you know how it went. Thank you! $\endgroup$
    – Francis L.
    May 18, 2019 at 2:18
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    $\begingroup$ Woods metal can used for this en.wikipedia.org/wiki/Wood%27s_metal $\endgroup$
    – Waylander
    May 18, 2019 at 7:11
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    $\begingroup$ Word of warning -- this idea just came to me out of the blue. I'm not a practitioner. I have no idea if a solid-liquid zinc bath is something that's routinely done; if not, there may be good reasons why not. $\endgroup$
    – jeffB
    May 19, 2019 at 4:54
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You can try $\ce{C30}$ hydrocarbon, triacontane (CAS #: 638-68-6). It is a straight chain hydrocarbon with formula weight of $\pu{422.8 gmol^{-1}}$ ($n$-$\ce{C30H62}$). It is a solid at $\pu{25 ^{\circ}C}$ and NIST Webbook reported its boiling point as $\pu{722.9 K}$ ($\approx\pu{450 ^{\circ}C}$) at $\pu{1 atm}$. More phase changing data can be found in [NIST Webbook] and following reference:

  • J. S. Chickos, W. Hanshaw, “Vapor Pressures and Vaporization Enthalpies of the n-Alkanes from $\ce{C21}$ to $\ce{C30}$ at $\mathrm{T} = \pu{298.15 K})$ by Correlation Gas Chromatography,” J. Chem. Eng. Data 2004, 49(1), 77–85 (DOI: 10.1021/je0301747).
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    $\begingroup$ The vapor pressure would be significant at 400C (a mere 50C below boiling point), even if it didn't start to carbonize. Those vapors probably would ignite. $\endgroup$
    – Kevin Kostlan
    May 18, 2019 at 21:01
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    $\begingroup$ @Kevin Kostlan: I know the risk. I was thinking about a salt bath to be honest with you. But OP insisted that "he's looking for a hydrocarbon fraction/blend with the boiling point in this range" and then this'd be the answer. $\endgroup$
    – Mathew Mahindaratne
    May 19, 2019 at 4:55

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