4. The elementary isomerization reaction A C will be carried out in a soft gel that is attached to a flat solid surface. The reactant A is available as part of a gas that also contains oxygen. The reaction only can proceed in the presence of a catalyst that is soluble in the gel but that will oxidize and deactivate if exposed to oxygen. To avoid catalyst oxidation, we propose to impregnate with a catalyst only half of the gel layer (0