# Is there a catalyst that will reduce an alcohol to an alkane?

There are many reduction methods of going from an alcohol to an alkane: http://www.transtutors.com/chemistry-homework-help/hydrocarbons/reduction-of-alcohols.aspx

And there are catalytic methods of adding hydrogen gas to aldehydes and keystones to convert them into alcohols: http://jmcct.com/products-services/product_p404.html

However, I have not found a catalytic method of converting an alcohol into an alkane using a catalyst and possibly hydrogen. The fewer non-catalytic entities the better.

• What about acid-catalyzed dehydration? – Dissenter Sep 17 '14 at 0:52
• @Dissenter I would prefer to avoid reagents that are not recoverable because of cost considerations. That is why I asked for catalysts. – Dale Sep 28 '14 at 18:21
• It's an acid-catalyzed reaction so the reagent (sulfuric acid) is preserved. @JoeHobbit. – Dissenter Sep 28 '14 at 19:49
• What I meant is that you can catalyze the dehydration of the alcohol and form an alkene and then hydrogenate or otherwise reduce to an alkane. – Dissenter Sep 28 '14 at 19:50
• @Dissenter That sounds terrific. – Dale Aug 10 '16 at 12:09

Here is a method for converting secondary and tertiary alcohols into the corresponding alkane using $\ce{InCl3}$ as a catalyst. Chlorodiphenylsilane is the only reagent used in addition to the catalyst. The method works in the presence of common functional groups leaving them untouched.

Since primary alcohols are unreactive, this reaction can be used to selectively reduce secondary and tertiary alcohols in their presence. An abstract showing a number of examples of the reaction can be found here.

This is a very limited situation, but benzylic alcohols can be reduced to the corresponding alkyl group with simple hydrogenolysis conditions, hydrogen gas with Pd/C. This is similar to the cleavage of benzyl ethers, a common protecting group. Looking at it this way, the reaction deprotects water. An example of this reaction that I ran long ago is depicted below.

Developing a more general method for this transformation is an ongoing field of research, with many methods published. That often means that there isn't one single best method (yet). A 2013 publication from Li and coworkers used an iridium complex with hydrazine as the terminal oxidant. Benzylic, allylic, and notably primary alcohols were successfully reduced, although the benzylic/allylic substrates worked much better. The introduction offers a brief description on the state of the field: Iridium-Catalyzed Direct Dehydroxylation of Alcohols

• As a side note, even zinc dust can reduce phenols to benzenes. – Pritt says Reinstate Monica May 18 '17 at 16:36

The following not catalytic and does not use hydrogen but tin hydrides:

1. Convert the alcohol to a xanthate
2. Treat with $\ce{Bu3SnH}$ and AIBN

Yes, it's the Barton-McCombie reaction.

If you don't mind a bit of photochemistry, use the method described by Isao Saito (DOI):

1. Convert the alcohol to a m-trifluoromethylbenzoate
2. Photolyze (high pressure $\ce{Hg}$ lamp) in THF/water in the presence of N-methylcarbazole as an electron donor

Red P + HI is a very strong reducing agent. It would reduce your alcohol to an alkane, but it might reduce other functional groups present as well. See earlier question for details.