Additive manufacturing (3D printing) is a disruptive technology that is changing production systems globally.

Significant enantioselective recognition has been achieved through the introduction of long range ordered and highly interconnected 300 nm diameter pores in molecularly imprinted polymer matrices.

We have identified the most likely reaction mechanism for oxidizing heptafulvenes to the corresponding tropones by experimental and theoretical investigations. The experimental studies were done by coupling a three-dimensional printed miniaturized reactor with an integrated electrospray ionization needle to a mass spectrometer. Using the experimentally observed ions as a basis, nine alternative reaction pathways were investigated with density functional theory calculations. The lowest energy reaction pathway starts with the formation of an epoxide that is opened upon the addition of a second equivalent of the oxidizing species meta-chloroperoxybenzoic acid. The adduct formed then undergoes a Criegee-like rearrangement to yield a positively charged hemiketal, which on deprotonation dissociates into acetone and tropone. Overall, the reaction mechanism resembles a Hock-like rearrangement.

A simple flow chemistry microreactor with an electrospray ionization tip for real time mass spectrometric reaction monitoring is introduced. The microreactor was fabricated by a laser-based additive manufacturing technique from acid-resistant stainless steel 316L. The functionality of the microreactor was investigated by using an inverse electron demand Diels-Alder and subsequent retro Diels-Alder reaction for testing. Challenges and problems encountered are discussed and improvements proposed. Adsorption of reagents to the rough stainless steel channel walls, short length of the reaction channel, and making a proper ESI tip present challenges, but the microreactor is potentially useful as a disposable device.

Correction for ‘A miniaturised 3D printed polypropylene reactor for online reaction analysis by mass spectrometry’ by Gianmario Scotti et al., React. Chem. Eng., 2017, 2, 299–303.

The first miniaturised 3D printed polypropylene reactor with an integrated nanoelectrospray ionisation capillary and a stir bar for mass spectrometric online reaction monitoring.

A measurement set-up using a microchip for on-line mass spectrometric investigations of reaction mechanisms using either electrospray ionization or atmospheric pressure photoionization is presented.