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I'm preparing to do a thiolclick reaction and to get a homogenous phase I found it's best to use DMSO/ethanol as solvent for the -ene and thiol reagents. I need the ethanol specifically for hole-capturing, and the DMSO seems to dissolve both reagents well.

To validate my results I want to use H-NMR however ethanol tends to give some messy peaks so I would like to evaporate it off at room temperature under a fume hood.

I was wondering if any of you know if DMSO/ethanol are problematic together when trying to evaporate them off.

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    $\begingroup$ DMSO boiling point is 189 deg C. It has its implications toward ethanol and dissolved organic matter $\endgroup$
    – Poutnik
    Commented May 8, 2023 at 9:44
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    $\begingroup$ Ethanol is often used as a co-solvent to evaporate DMSO and similar high-b.p. solvents under vacuum at the temperatures below 25 °C. Are you planning to reconstitute your product (BTW which one, exactly?) in DMSO-d6 for NMR, or is your goal is to selectively remove ethanol and leaving DMSO intact? What do you mean by ethanol's "messy peaks" and are you absolutely sure it's EtOH causing the issue? Also, what "hole-capturing" are you referring to? Is there a photocatalytic process involved, or you are speaking of porogenic properties of ethanol/DMSO mix? $\endgroup$
    – andselisk
    Commented May 8, 2023 at 10:50

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The boiling point of DMSO is about 462 kelvin and that of ethanol is about 352 kelvin, you should be able to evaporate ethanol with ease without losing any of the DMSO solvent. For fast evaporation, use low pressure evaporation at the boiling point of ethanol (at the lower pressure) while constantly stirring the solution.

Caution

However, so that you don't lose any of your product, you have to take into account the boiling point and vapor pressure of your product as well. If your product has boiling point significantly lower than that of ethanol, it is best to evaporate the product and collect it in a different vessel containing DMSO.

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    $\begingroup$ The kelvin as the unit of measurement is not capitalized. $\endgroup$
    – andselisk
    Commented May 8, 2023 at 10:53
  • $\begingroup$ @andselisk sorry but isn't the unit named after Lord Kelvin (William Thompson). Shouldn't it be capitalized? Actually, when writing temperatures on the absolute scale K/Kelvin/kelvin is not used at all, I only added it for clarity. Web search does agree with you; therefore, I have incorporated your suggestion. $\endgroup$
    – ananta
    Commented May 8, 2023 at 10:54
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    $\begingroup$ In place of randomly searching the web and drawing a conclusion from the most popular results that your search engine spoon-feeds you with, I recommend to develop a habit of referring to the authoritative sources directly. Here, I suggest reading sections 2.3.1 Base units and 5.3 Unit names of the SI Brochure. Alternatively, just avoid *** and read good literature that follow conventions and you will automatically write correctly because you will visually memorize how the term or its symbol should be formatted for a suitable occasion. $\endgroup$
    – andselisk
    Commented May 8, 2023 at 11:10
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    $\begingroup$ @ananta Hello ananta. All the names in the SI units are not capitalized, it is kelvin (not Kelvin); it is ampere (not Ampere); even though these are surnames of brilliant people. However, you can say Celsius, Fahrenheit, or Rankine. Preferably, don't use "°" for absolute temperature scales like kelvin or Rankine, and use $^\circ F$ or $^\circ C$ for Fahrenheit and Celsius scales, which are relative temperature scales. $\endgroup$ Commented May 8, 2023 at 14:42

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