Are Chemical Reactions dependent on reagent orientation?
Indirect Evidence: yes
"Common Sense" (dates back to ancient Greece)
"Chemical Intuition" (more modern version of above)
Electron & X-ray diffraction
Kinetic steric factors
Direct Evidence: YES!
We orient dipolar molecules in molecular beams and compare the reactivity at the positive end and the negative end.
(more coming--this research supported by the NSF)