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Topic: Repeated synthesis of pentan-2-one  (Read 2522 times)

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Offline Babcock_Hall

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Re: Repeated synthesis of pentan-2-one
« Reply #15 on: July 05, 2020, 01:45:11 PM »
How would distillation separate water from 2-pentanone?  Can you cite the reference to the procedure that you are following?
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Offline lukas.stib

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Re: Repeated synthesis of pentan-2-one
« Reply #16 on: July 05, 2020, 01:53:39 PM »
In the instructions, they wrote that the oily layer was dried over CaCl 2 and then distilled. I distilled immediately after reflux (not 2 layers), and I dried the distillate with CaCl2. I poured a lot of CaCl2. An aqueous layer of CaCl 2 and water was formed below, which is very large, so that the water distillate contained very much. I have molecular sieves 3A, which I haven't used yet, but I have little CaCl2, so I'll probably add the sieves later.

And i used this ester:
https://en.wikipedia.org/wiki/Ethyl_acetoacetate
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Offline AWK

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Re: Repeated synthesis of pentan-2-one
« Reply #17 on: July 05, 2020, 01:58:31 PM »
This ester gives acetone.
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Offline lukas.stib

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Re: Repeated synthesis of pentan-2-one
« Reply #18 on: July 05, 2020, 02:01:54 PM »
It's weird, they say in my tutorial that pentan-2-one should be formed  :o
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Offline lukas.stib

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Re: Repeated synthesis of pentan-2-one
« Reply #19 on: July 05, 2020, 02:05:46 PM »
I ´m adding a file.
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Offline AWK

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Re: Repeated synthesis of pentan-2-one
« Reply #20 on: July 05, 2020, 02:09:43 PM »
Ethylacetoacetic ester  and ethyl acetoacetate  - different compounds.
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Offline lukas.stib

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Re: Repeated synthesis of pentan-2-one
« Reply #21 on: July 05, 2020, 02:31:14 PM »
It's weird, the internet search  always finds me ethyl acetoacetate  :o
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Offline AWK

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Re: Repeated synthesis of pentan-2-one
« Reply #22 on: July 05, 2020, 02:40:47 PM »
Search correctly
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Offline lukas.stib

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Re: Repeated synthesis of pentan-2-one
« Reply #23 on: July 05, 2020, 02:53:35 PM »
OK, thank you very much for your help for me.

So therefore explains why the boiling point in my distillation began at 61°C, and was felt after acetone; it was acetone !!!

OK, for pentan-2-one I must have ethyl-2-ethyl-3-oxobutanoate, or by oxidation of 2-pentanol by dichromate.

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Offline rolnor

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Re: Repeated synthesis of pentan-2-one
« Reply #24 on: July 05, 2020, 04:27:10 PM »
So, the startingmaterial was not OK, nice that you got that cleared up. Why do you want to make this ketone, you can buy it?
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Offline lukas.stib

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Re: Repeated synthesis of pentan-2-one
« Reply #25 on: July 05, 2020, 04:45:32 PM »
I'm very embarrassed that I was wrong. Unfortunately, I live in the Czech Republic, and my internet browser has always found ethyl acetoacetate, which is bad for this synthesis. Simply, these 2 names of these esters merged into one.

I can buy pentan-2-on, but I do it for fun, and when I buy it, I don't like it anymore...
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Offline AWK

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Re: Repeated synthesis of pentan-2-one
« Reply #26 on: July 06, 2020, 12:25:41 AM »
Ethyl 2-ethylacetoacetate is about 50 times more expensive than ethyl acetoacetate.
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Offline lukas.stib

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Re: Repeated synthesis of pentan-2-one
« Reply #27 on: July 06, 2020, 02:36:21 AM »
I know, I've found it in several stores, and the price is crazy!  :o
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Offline AWK

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Re: Repeated synthesis of pentan-2-one
« Reply #28 on: July 06, 2020, 02:56:02 AM »
The need for this reagent is negligible and the synthesis on a larger scale is quite dangerous. That is why reagent companies use synthesis on demand and hence the high price. But the synthesis itself is quite simple, although requiring anhydrous conditions.
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Offline lukas.stib

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Re: Repeated synthesis of pentan-2-one
« Reply #29 on: July 06, 2020, 04:34:20 AM »
OK. So, thank you very much, you help me very much.

Lukáš S.
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