So I'm basically doing an experiment where I measure the effect of pH on the yield of alcohol within the acid catalyzed hydration of ethene. Essentially, all other details aside, I get a mixture of ethanol and ethyl chloride solutions at the end of my experiment. I want to find the total amount of either. I want to use a simple method to determine the amount of each in the solution. I want to avoid using fractional distillation, if possible. I need help to do this.


1 Answer 1


If you are certain that there are no other halogenated byproducts or reagents remaining in your solution, and that any levels of bromine and iodine would be negligible compared to chlorine (fluorine would not be detected), then one of the total halogen analysis (TX) methods would be a good choice.

If this is an ongoing analysis that you need to set up, I suggest the Carius halogen method. Wikipedia gives a good overview here:

The Carius halogen method in analytical chemistry is a method for the quantitative determination of halogens in chemical substances. A known mass of an organic compound is heated with fuming nitric acid in the presence of silver nitrate contained in a hard glass tube known as carius tube, in a furnace. Carbon and hydrogen present in the compound are oxidised to carbon dioxide and water. The halogen present forms the corresponding silver halide (AgX). It is filtered, washed, dried and weighed.

Alternatively, depending on the equipment available to you, you could also do an oxygen bomb combustion of the sample with a bicarbonate absorbant, followed by either titration of the resulting chloride or ion chromatographic (IC) analysis. In the case of the IC finish, you can usually just use the IC eluent as the adsorbant.

If you are only going to do this analysis once, or only rarely, then I would strongly suggest a commercial TX anaysis using Standard Methods - For the Examination of Water and Wastewater, Method 9020. Method 9020B is for the analysis of total organic halogens (TOX) in water, which is not appropriate for your analysis as a whole because it includes a step for extracting trace amounts of organics from water onto activated carbon. But, then a TX analysis is performed on the activated carbon, which is what you would want to do for your compound rather than for the activated carbon. This is typically about an $80 analysis.

Regardless of the TX technique used, you would of course then assume that all of the halogen came from the ethyl chloride and calculate the ethyl chloride concentration from there.

  • $\begingroup$ Thank you for the answer. The carius method seems to require equipment that my school lab might not have. In particular, the carius tube and the furnace, though I am wondering if I can still do the same analysis without these apparatus. Suppose now that my solution also contained alcohol within it. In particular, I'm extremely sure that the alcohol present is only going to be ethyl alcohol. Is there any test that I can do to find the amount of ethanol in it? Thanks so much once again. $\endgroup$ Feb 25, 2017 at 19:32
  • $\begingroup$ Do you have access to either gas or liquid chromatography equipment? $\endgroup$
    – airhuff
    Feb 25, 2017 at 19:46
  • $\begingroup$ There really isn't a simple, non-instrumental quantitative analysis for alcohols. Going back to the commercial route, if you can assume the only O in your product is from the alcohol, then you could get an O analysis done for about $35-$45. But, if you were to go with that route, there is a combustion/ion selective electrode method for about the same price that would give more accurate results (for the ethyl chloride of course). I think the most likely method you'd be able to do yourself is the bomb combustion followed by gravimetric determination after precipitating Cl- with AgNO3. $\endgroup$
    – airhuff
    Feb 25, 2017 at 20:33
  • $\begingroup$ I'm looking for methods which are extremely simple. Like, I was thinking that, since ethyl chloride's hydrogens are barely acidic and ethanol is way more acidic than ethyl chloride, would it not be possible for me to stick a pH probe into the final solution, measure the pH and calculate the yield of ethanol directly using acid-base equilibrium calculations? $\endgroup$ Feb 26, 2017 at 3:54
  • $\begingroup$ OK, knowing what you do/don't have available is very helpful. Yes a fractional distillation should be a good way to go, with a couple caveats. If you are purely doing it for analytical purposes, and not trying to recover the ethyl chloride, that will be particularly easy. If you have a small distillation apparatus and enough material to sacrifice for the distillation, then you could just weigh the mixture, let the ethyl chloride boil off, then weigh the remaining ethanol. If you want to separate and keep the fractions, remember that ethyl chloride boils at 12C and won't stick around at RT. $\endgroup$
    – airhuff
    Feb 26, 2017 at 3:54

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