Chemical reaction have 2 classifications: Exothermic and Endothermic. Exothermic is when the chemical give off heat in the reaction. Endothermic is when the chemical obsorb heat in the reaction. So... If one exploit Endothermic reaction by keep taking heat from the low temperature heat sink and later use it to produce a higher temperature environment. Have we not indirectly violate the 2nd law of thermodynamics?