I am working on the partial reduction of alkyne to cis-alkene using Lindlar's catalyst. However, I am not really sure the amount of Lindlar catalyst to be added. Commerical source is 5% Pd on CaCO3, poisoned with lead. How much catalyst should be used relative to the substrates?
My second question is how much quinoline should be added (relative to the Lindar catalyst). In practice, trace amount of trans-alkene would also be produced under Lindlar's partial reduction conditions. When the amount of quinoline (relative to Lindlar catalyst) is insufficient, more undesired trans-alkene would be produced (difficult to separate trans- and cis-alkenes). However, the reaction rate becomes sluggish when too much quinoline is added.