α-(Bromomethyl)-α-butyl-4-chlorobenzeneacetonitrile-d9 is an intermediate used in the synthesis of Myclobutanil-d9 (M831402), which is the labeled analogue of Myclobutanil (M831400), an fungicide used on a wide range of food crops. Myclobutanil inhibits the biosynthesis of ergosterol, a critical component of fungal membranes.