– 2-Methylpropionic-d7 acid is a deuterated compound of 2-Methylpropionic acid. 2-Methylpropionic acid has a CAS number of 79-31-2. Isobutyric acid Description Isobutyric acid is a carboxylic or short chain fatty acid with characteristic sweat-like smell. Small amount of isobutyrate is generated via microbial (gut) metabolism. Small amounts may also be found in certain foods or fermented beverages. There is anosmia (genetic inability to smell) for the odor of isobutyric acid with a frequency of about 2.5%. (OMIM 207000 ). Isobutyric acid is slightly soluble in water but much more soluble in ethanol, ether and organic solvents. Isobutyric acid can affect people if breathed in and may be absorbed through the skin. Contact can irritate and burn the skin and eyes. Breathing Isobutyric acid can irritate the nose, throat and lungs causing coughing, wheezing and/or shortness of breath.