A detailed process simulation for the production process of a valuable alternative reactant to produce a polyamide, i.e., m-xylylenediamine (MXDA) using Aspen Plus has been performed. A comparative life cycle assessment of MXDA with an equivalent polymer precursor, i.e., hexamethylenediamine (HMDA), has been carried out using the material and energy balances obtained through process simulation. Since neither of the two compounds outperformed the other in the impact assessment's environmental analysis, a general trade-off must be determined, even though slightly better performances are gained by m-xylylenediamine. The uncertainty related to the energy demand, which is one of the most influencing parameters, has been assessed to identify the implications of energy losses. The outcomes are actually reversed when the energy requirement for MXDA is increased by 25%, suggesting a general preference for HMDA. Therefore, particular care should be taken on energy optimization when implementing MXDA manufacturing process industrially.