4-Benzyl- 2-thiophenecarboxylic Acid-d7 is labelled 4-Benzyl- 2-thiophenecarboxylic Acid (B315140) which is a derivative of 2-Thenoic Acid (T343505), used in the synthesis of pharmaceutical and biologically active compounds. 2-Thenoic Acid is also shown to be utilized by presumptive Rhodococcus bacterium in soil, as a sole source of carbon.