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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Fischer on December 12, 2013, 09:33:14 AM

Title: Kind of confused... I think my professor has made a mistake.
Post by: Fischer on December 12, 2013, 09:33:14 AM
Hey guys.

So my professor was doing some problems on the board,

He did the following;

Cyclohexane + Na  :rarrow: cyclohexane (secondary carbocation) + NaH

I am very confused about this... He formed a secondary carbocation from adding Na to cyclohexane. I did not ask him in class as I just realized what he did when reading through my notes. Is this even possible.
Title: Re: Kind of confused... I think my professor has made a mistake.
Post by: Fischer on December 12, 2013, 09:53:40 AM
Any ideas guys?
Title: Re: Kind of confused... I think my professor has made a mistake.
Post by: AlphaScent on December 12, 2013, 09:57:51 AM
I would think that this reaction would not proceed.  I rinse my sodium before using it with hexanes all the time and there is no reaction.  I just do not think the protons are acidic enough.  I would email and ask him.  I do not think that is good theory to teach.  I could be wrong due to some interaction I am not taking into account when it is in the chair conformation.  But like I said, do not believe there will be a reaction.  He could just be doing as theory, not practical. 

Ask him..Id like to know what he says.
Title: Re: Kind of confused... I think my professor has made a mistake.
Post by: Fischer on December 12, 2013, 10:01:55 AM
Yeah I'm going to ask him... Unless as you stated, we are not taking something into account but I highly  doubt that.
Title: Re: Kind of confused... I think my professor has made a mistake.
Post by: AWK on December 12, 2013, 10:43:20 AM
May be your teacher thought about cyclohexanol?
Title: Re: Kind of confused... I think my professor has made a mistake.
Post by: Dan on December 12, 2013, 02:38:18 PM
No, it's nonsense; CyH + Na :rarrow: Cy+ + NaH is not even balanced.

The reaction with cyclohexanol is CyOH + Na :rarrow: CyONa + 1/2 H2

He's made a mistake, you should ask him to clarify.
Title: Re: Kind of confused... I think my professor has made a mistake.
Post by: orgopete on December 12, 2013, 06:15:22 PM
Often we can guess what might have been meant, even when there is an error. In this case, I can't even do that. Sodium metal is an electron donor and the net result shows sodium has donated its electron, but the recipient ends up with a positive charge. This is clearly an error (assuming the notes are correct). A simple test, the net charges on each side of the arrow must balance. In this case, they do not.