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11-17-2014, 11:00 AM (This post was last modified: 11-17-2014 11:01 AM by i.kovacs.)
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We have received this question to

We recently purchased an H-Cube Pro and I’m attempting to remove a benzyl protecting group from an alcohol. So far we’ve been able to successfully remove the benzyl protecting group but we’re also seeing reduction of a chlorine on a phenyl ring in another section of the molecule. Have you had any experience with selective deprotection of a benzyl in the presence of aryl halogens? If you could give us some procedure suggestions that would be great.

The reaction you would like to perform is a difficult one, because both of the reactions run well, with Pd catalysts and at low pressures.
If you would like to suppress the dehalogenation reaction, than you should use a less active catalysts (1% Pd/C or 5% Pd/C). With a more active catalyst, you can observe a selectivity increase after some time because of the specific poisoning of the catalyst, which reduces its dehydrohalogenation activity.
An acidic media, especially sulfuric acid, generally suppresses the dehalogenation, so you may try this as well. The acidic support also can improve your reactions selectivity, so you can use alumina or silica supported Palladium catalysts.
If you cannot optimize your process with these modifications, than you can try a platinum catalyst. The dehydrohalogenation activity of platinum is much lower, and in certain cases it can remove benzyl group.
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Deprotection - i.kovacs - 11-17-2014 11:00 AM

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