If you are reacting SOCl2 with a molecule with a carboxylic acid on one end and an ester on the other, would would be the end product.?

In the reaction, only the carboxylic acid (-COOH) is converted to acyl chloride (-COCl), and the ester is unchanged.

In the reaction of using SOCl₂ as the reagent, pyridine (C₅H₅N) is usually used as the solvent. The HCl formed would be absorbed by the pyridine to become C₅H₅NH⁺Cl⁻. Hence, the ester would NOT be affected the HCl formed.