Energetic assessment of the Suzuki–Miyaura reaction: a curtate life cycle assessment as an easily understandable and applicable tool for reaction optimization

The solvent-less Pd-catalyzed Suzuki–Miyaura cross coupling of different aryl halides with phenylboronic acid and an in situ generated solid base was investigated in order to study the influence of different modes of energy entry. For this reason reactions were performed in two different ball-milling set-ups and also different techniques of microwave irradiation have been applied. Combination of reaction data (yield, selectivity, batch size) with energetic data (line power consumption) was used to generalize the results as a curtate life cycle assessment (cLCA), breaking down the reaction to the reaction step, neglecting up- and downstream processes. Thus cLCA was applied for early-level reaction optimization and as decision guidance for constitutive experiments. Under the applied reaction and boundary conditions applied for the solvent-free Suzuki–Miyaura reaction ball milling is proven to be a more effective tool for energy entry than microwave irradiation.