Carboxylic Acids and Nitriles Carboxylic acids (-CO2H) are present in most biological pathways and are the biological starting A carboxylic acid materials from which other acyl derivatives are made 。 0 O(OR' An acid chloride An ester An amide A thioester An acyl phosphate Cholic acid is a major component of human bile HO HO OH Cholic acidCarboxylic acids (-CO2H) are present in most biological pathways and are the biological starting materials from which other acyl derivatives are made Cholic acid is a major component of human bile Carboxylic Acids and Nitriles