IS anybody can tell me which base should be put in the 2-chloroethanol solutions to m

[nihong]

HI~all
IS anybody can tell me which base should be put in the 2-chloroethanol solutions to make them PH = 7?

 

[jpanhalt]

It would be immensely helpful to know all compounds and their concentrations in the solution. You do not state the solution is in water. I presume it is. Is the solution just 2-chloroethanol (aka ethylene chlorohydrin) and pure water?

If so, how are you measuring the pH of the pure water? Measuring the pH of distilled/deionized water can be difficult, and I suggest you refer to an appropriate standard for doing that. Here are a couple of articles on that matter:

**broken link removed**

http://static.fishersci.com/cmsasse...hod_1029_pH_Ultra_Pure_Water_257456-001_A.pdf

The pH of pure water when measured directly with a standard electrode will usually be less the 7.0, often averaging 5.8. Adding chloroethanol to that water may actually raise the pH. Why do you want to raise it more? Note, the pKa of 2-chloroethanol is 14.3. That is, it is very weakly ionized. The acidity you are detecting in water is probably a result of dissolved CO2 or artifacts from measurement , as described in the two references given above.

John

 

[nihong]

Can you tell me how to make the ph of the 95 per cent of 2-chloroethanol and 4~5 per cent of diethylene dioxide become Neutral？
e~,i know my words is not rigorous， you known the 2-chloroethanol is the products in my experiment，but in my experiment ,Mass spectrometer tells me there is 95 per cent of 2-chloroethanol and 4~5 per cent of diethylene dioxide,but the PH test paper tell me there is a large proton in 2-chloroethanol,but how to neutralization it without introducing impurities ？
thank you very much!!!!!

 

[jpanhalt]

The simple answer is that pH test paper is for aqueous solutions. It is simply wrong to use pH test papers for the mixture you describe.

The correct colors with test paper depend on water -- a lot of it. As an experiment, take any hydrocarbon solvent, like hexane to cetane, and test the pH with pH paper. You will get a bizarre result. The actual pH by definition is quite high (>>14). Diethylene dioxide (1,4-dioxane) is non-protic. It does not dissociate to any significant extent. Any protons in your solution are from the 2-chloroethanol, which as mentioned has a pKa of over 14.

Just what are you trying to neutralize? Can you draw the anion?

John

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Edit: While I don't recommend using pH paper in the situation you describe. You might take pure water (high-resistance deionized), say 20 mL. Add one drop of concentrated KCl solution, measure the pH. Then add 2 mL of your chloroethanol/dioxane mixture, and measure the pH again. I suspect the change you see will be small, which would be consistent with low "acid" in the chloroethanol/dioxane mixture.

Are you sure the mixture doesn't have excess mineral acid from its synthesis?

Edit#2: Here is an article that may address that problem (I don't have access to ACS journals at the moment): https://pubs.acs.org/doi/abs/10.1021/ie50532a028

John

 

[nihong]

e~ i think you get the wrong directions.i want to get pure 2-chloroethanol without water,without acid but only 2-chloroethanol.Do you have any suitable solutions to deal with these problems.
P.S. Can you tell me can PH meter be used in pure 2-chloroethanol?
thank you

 

[jpanhalt]

As pointed out in the literature link I provided, 2-chloroethanol is an industrial chemical that has been available for a very long time. If you are trying to develop your own synthesis more than 150 years after it was first synthesized, I suggest referring to the literature.

If you want specific help with a particular reaction you are investigating, you will need to tell us more detail of what you have done. In any event, have you reviewed the literature on its purification?

I don't see that this is really an electronic question. I am more than anxious to help you, if I can. But industrial chemistry sometimes uses reactions and conditions that are secret or difficult to duplicate on small scale in a student laboratory.

John

 

[nihong]

Thank you very much first.can you tell me the weather the pure 2-chloroethanol is Acidic or prevalently alkaline？this problem is very important for our experiment,and reactants are ethanediol and thionyl chloride