4-(4-Chlorophenyl)-3-cyclohexene-1-carboxylic Acid-d4 is the isotope labelled analog of 4-(4-Chlorophenyl)-3-cyclohexene-1-carboxylic Acid. 4-(4-Chlorophenyl)-3-cyclohexene-1-carboxylic Acid is an impurity of atovaquone (A793500). Atovaquone is a hydroxynaphthoquinone derivative that inhibits mitochondrial electron transport. Antipneumocystic.