Competitive Chemisorption between Pairs of Cinchona Alkaloids and Related Compounds from Solution onto Platinum Surfaces

Quinoline-derived compounds exhibit the following relative chemisorption strengths from CCl₄ solutions onto platinum surfaces, as determined by in-situ infrared spectroscopy:  quinine, quinidine > cinchonidine > cinchonine > 6-methoxyquinoline > lepidine > quinoline. This sequence explains nonlinear enantioselectivity effects with cinchona chiral modifiers in hydrogenation catalysis.