[dunno260]

This is a passing curiosity, but in the reduction of propargylic alcohols to the (Z)-allylic alcohols with Lindlar's catalyst, I have seen numerous procedures that call for adding 5-10 drops of chloroform to the reaction (typically the solvent is ethyl acetate).  Is the chloroform somehow poisoning the catalyst, acting as a weak acid, or something else.  I haven't seen this until now but it appears fairly common.

Thanks

[nox]

My guess would be as a very weak acid. Old(er) samples of chloroform tend to accumulate some HCl, so maybe that's why.

[BobfromNC]

The hydrogen reacts with the chloroform to generate a bit of dry HCl in situ.   I presume that this reaction goes better with an acidic catalyst.  There are many tricks for generating a small amount of HCl-if you ever see soeone adding acetyl chloride to a reaction in MeOh, it is the same, as that generates methyl acetate ( a gasd) and HCl.  Much cheaper and simpler than either buying HCl in a non-aqueous solvent, or getting a cylinder of HCl. 

Bob