  Molecular polaritons, hybrid light-matter states resulting from strong cavity
coupling of optical transitions, may provide a new route to guide chemical
reactions. However, demonstrations of cavity-modified reactivity in clean
benchmark systems are still needed to clarify the mechanisms and scope of
polariton chemistry. Here, we use transient absorption to observe the ultrafast
dynamics of CN radicals interacting with a cyclohexane ($c$-C$_6$H$_{12}$) and
chloroform (CHCl$_3$) solvent mixture under vibrational strong coupling of the
brightest C$-$H stretching mode of $c$-C$_6$H$_{12}$. By modulating the
$c$-C$_6$H$_{12}$:CHCl$_3$ ratio, we explore how solvent complexation and
hydrogen (H)-abstraction processes proceed under collective cavity coupling
strengths ranging from 55$-$85 cm$^{-1}$. Reaction rates remain unchanged for
all extracavity, on resonance, and off-resonance cavity coupling conditions,
regardless of coupling strength. These results suggest that insufficient
vibrational cavity coupling strength may not be the determining factor for the
negligible cavity effects observed previously in H-abstraction reactions of CN
with CHCl$_3$.
