# 400–430 degrees Celsius heated bath

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.

• 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? – jeffB May 18 '19 at 0:48
• 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. – Francis L. May 18 '19 at 1:53
• Also, to rig such a mantle on ones own would be no small feat. Not to mention being able to afford one. – Francis L. May 18 '19 at 2:07
• 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. – andselisk May 18 '19 at 6:37
• What's wrong with carrying out your reaction in a furnace? – svavil May 18 '19 at 7:37

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?

• I have to say this is an interesting idea. I'll give it a good thought. – Francis L. May 18 '19 at 2:15
• 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! – Francis L. May 18 '19 at 2:18
• Woods metal can used for this en.wikipedia.org/wiki/Wood%27s_metal – Waylander May 18 '19 at 7:11
• 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. – jeffB May 19 '19 at 4:54

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).
• 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. – Kevin Kostlan May 18 '19 at 21:01
• @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. – Mathew Mahindaratne May 19 '19 at 4:55