October 31, 2020, 05:43:47 PM
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Topic: Help in the following synthesis  (Read 362 times)

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Offline ganesh2gig

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Help in the following synthesis
« on: October 12, 2020, 04:58:15 AM »
Hi all , Hope you guys are safe from COVID -19 .

I was doing a synthesis and I am not able to get the desired product , the synthesis is attached . I am getting a  gel likes substance instead of a precipitate , does somebody know why ?  somebody please help me . 

The first step is giving problem
« Last Edit: October 12, 2020, 06:19:08 AM by ganesh2gig »

Offline kriggy

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Re: Help in the following synthesis
« Reply #1 on: October 12, 2020, 06:03:38 AM »
whic step is giving you problems?

Offline ganesh2gig

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Re: Help in the following synthesis
« Reply #2 on: October 12, 2020, 06:20:12 AM »
whic step is giving you problems?
The first step , its basically a Fischer indole synthesis , but I am not getting the precipitate instead I get a lump of mass .

Offline rolnor

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Re: Help in the following synthesis
« Reply #3 on: October 12, 2020, 04:27:21 PM »
Did you follow the recipe carefully? Slow addition can be critical.

Offline ganesh2gig

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Re: Help in the following synthesis
« Reply #4 on: October 13, 2020, 07:37:51 AM »
I am following it verbatim , I  had done this before in  a different lab and got nice results as well , after few years I am not getting it at all . Even for conversion to hydrazide I am not getting a PPT at all . I am guessing  ammonia will be released in the reaction which is altering the course of the reaction .

Offline rolnor

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Re: Help in the following synthesis
« Reply #5 on: October 13, 2020, 07:41:40 AM »
Then you need to check startingmaterial.

Offline ganesh2gig

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Re: Help in the following synthesis
« Reply #6 on: October 20, 2020, 11:27:48 PM »
Tried new material does not work . 

I am at the end of rope here .

Offline rolnor

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Re: Help in the following synthesis
« Reply #7 on: October 21, 2020, 04:40:36 AM »
Can you run TLC? Maybe you need to run chromatography.

Offline GabrielTojo

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Re: Help in the following synthesis
« Reply #8 on: October 23, 2020, 07:21:40 PM »
I suspect that you are obtaining the desired compound, but it crystallizes with difficulty due to being contaminated with starting products. You could check it by doing an NMR of the raw mix.

Alternatively, faster and cheaper, you could check by TLC for the appearance of a new product in the reaction mixture. That new product should be the indole.

I suspect that by TLC you will see traces of starting products, in addition to the indole. Then you would only have to prolong the reaction some time more before carrying out the elaboration.

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