Elizabeth,

I think the observed products should come as no surprise.  If toluene  
was allowed to sit in a less than perfectly sealed container for a  
number of years, the three hydrogens on the Methyl might be expected  
to get restless and do what comes naturally!

That is - form Resonance stabilized Radicals.  Such an Intermediate  
will also explain all three products you report, and also suggest  
that the hydroperoxide was the first product of the reaction of air  
( about 20% oxygen right? ) with toluene.  If that compound then  
decomposes by scission of the O-O bond, as peroxides are known to do,  
the stage is set to pick up a H atom on oxygen and form Benzyl  
alcohol.  Where might that H come from?  Well if it came from the  
alpha-C-H bond of another benzyloxy radical, it would form benzaldehyde.

Organic Chemistry can be a help, as well as the pain that too many of  
us remember from poorly taught undergraduate courses.

Best Wishes!

George Wahl

On Jul 9, 2007, at 4:03 PM, Elizabeth Gregory wrote:

> Hi everyone,
>
> Our department finally opened up a 5 gallon metal drum of toluene  
> earlier
> this summer. The drum is somewhere between 6 and 20 years old (you can
> imagine why I wanted to see it used up...).
>
> After a couple of days of "what the %**At_Symbol_Here**&# is this reaction by- 
> product?!",
> we've finally figured out that the toluene itself has the following
> impurities: benzaldehyde, benzyl alcohol, and benzyl hydroperoxide 
> (!!!). The
> total concentration of these impurities is about 240 mg/L of solution.
>
> Has anyone ever heard of toluene forming these products while it's  
> left
> sitting around unopened? This is a new one, both to me and our  
> resident
> organic chemist.
>
> Elizabeth Gregory
> Laboratory Manager
> Department of Chemistry
> SUNY College at Brockport
> Room 230 Smith Hall
> Brockport, NY 14420
> (585) 395-2210
> Fax: (585) 395-5805
> Email: egregory**At_Symbol_Here**brockport.edu
>

Previous post   |  Top of Page   |   Next post