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Topic: hydrogenation of alkynes  (Read 3775 times)

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Offline Doom91

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hydrogenation of alkynes
« on: February 16, 2009, 01:50:07 AM »
why does the use of hydrogen with Lindlar catalyst result in a cis isomer  while sodium ammonia reduction of alkynes results in a trans isomer
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Offline alexjaco

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Re: hydrogenation of alkynes
« Reply #1 on: February 16, 2009, 09:18:09 AM »
It is the mechanism from how the hydrogen is delivered. 
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Offline Vidya

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Re: hydrogenation of alkynes
« Reply #2 on: February 16, 2009, 09:49:48 AM »
Syn addition on the same side of alkyne gives cis  alkene
Anti addition on the opposite faces of alkyne gives trans alkene.
Now think and apply .
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Offline Doom91

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Re: hydrogenation of alkynes
« Reply #3 on: February 16, 2009, 10:54:18 AM »
so do u have
the mechanistic explanation for these two reaction
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Offline macman104

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Re: hydrogenation of alkynes
« Reply #4 on: February 16, 2009, 11:06:48 AM »
Quote from: Doom91 on February 16, 2009, 10:54:18 AM
so do u have
the mechanistic explanation for these two reaction
Part of learning in school is also getting better at doing research online and in textbooks.  I got this through a simple google search of "hydrogenation of alkyne":

Cis:  http://www.chem.ucalgary.ca/courses/350/Carey/Ch09/ch9-6.html
Trans:  http://www.chem.ucalgary.ca/courses/350/Carey/Ch09/ch9-7.html
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