July 01, 2022, 07:06:45 PM
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Topic: Distinguishing ketone from tertiary alcohol  (Read 416 times)

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Offline Aldebaran

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Distinguishing ketone from tertiary alcohol
« on: May 29, 2022, 06:41:49 AM »
Other than using 2,4-DNPH (orange ppt. with ketone) I am trying to think of another simple test to differentiate a ketone from tertiary alcohol. A quick Google didn't produce anything. Any helpful suggestions?
Many thanks.

Offline sharbeldam

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Re: Distinguishing ketone from tertiary alcohol
« Reply #1 on: May 29, 2022, 08:35:09 AM »
if its methyl ketone its haloform reaction.
otherwise, maybe lucas reagent
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Offline Aldebaran

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Re: Distinguishing ketone from tertiary alcohol
« Reply #2 on: May 29, 2022, 11:51:51 AM »
The question actually originated from considering linalool and ionone but got me thinking about the more general case and other options than 2,4-DNPH. Your suggestions are very helpful. I had thought about the Lucas reaction although I've never actually tried it out I am ashamed to admit!

Thanks.

Offline rolnor

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Re: Distinguishing ketone from tertiary alcohol
« Reply #3 on: May 30, 2022, 08:28:14 AM »
Whats wrong with DNPH?

Offline Aldebaran

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Re: Distinguishing ketone from tertiary alcohol
« Reply #4 on: May 30, 2022, 02:09:47 PM »
Nothing wrong with DNPH but one of my students asked if there were other tests and it got me thinking if there were other tests of general application.

Offline hollytara

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Re: Distinguishing ketone from tertiary alcohol
« Reply #5 on: June 01, 2022, 02:14:35 AM »
There are other compounds that make derivatives like DNPH - hydroxylamine to make the oxime for example. 

If you want something for the alcohol, ceric ammonium nitrate.

Offline Humr

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Re: Distinguishing ketone from tertiary alcohol
« Reply #6 on: June 02, 2022, 02:34:43 PM »
What about NaHSO3? It is used for purification of aldehydes or ketones. It forms crystals with those carbonyl compounds. Alcohol would not react.

Offline Meter

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Re: Distinguishing ketone from tertiary alcohol
« Reply #7 on: June 03, 2022, 06:42:51 AM »
Maybe not simple, but if the ketone and alcohol are the only functional groups present in the respective compounds, a Grignard reagent will react differently with both. Also, not sure, but maybe you can use HX acids, since these react with alcohols to form alkyl bromides + water, which would affect the overall pH. In a solution with a ketone, I doubt much would happen.

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