•A microfluidic electrolysis cell for synthesis on a laboratory scale•High conversions achieved from 0.25–3.0 mL min− 1•Productivities of multiple grams per hour demonstrated for two reactions•Excellent selectivity realized under a range of conditionsA spiral, extended channel length microflow cell designed for routine and convenient application in an organic synthesis laboratory is described. The performance of the cell is demonstrated using two syntheses and it is shown that high selectivities and high conversions in a single pass can be achieved as well as the formation of products at a rate of up to 25 mmol/h (~ 3 g/h). The cell is also well suited to carrying out the optimisation of reaction conditions with electrolyses completed on a timescale of minutes.

The synthesis of an octa-alkoxy substituted isotopically labeled naphthalene derivative, shown to have excellent properties in singlet NMR experiments, is described. This highly substituted naphthalene system, which incorporates an adjacent 13C spin pair, is readily accessed from a commercially available 13C2-labeled building block via sequential thermal alkynyl- and arylcyclobutenone rearrangements. The synthetic route incorporates a simple desymmetrization approach leading to a small difference in the chemical shifts of the 13C spin pair, a design constraint crucial for accessing nuclear singlet order.

•SSIMS was used to study corrosion inhibition of copper treated in insulating oil.•Desorption experiments allowed the study of the inhibitor stability in vacuum.•The energy of desorption of tolyltriazole under SSIMS conditions was calculated.•SSIMS imaging was shown to be an applicable new diagnostic tool for transformers.Static secondary ion mass spectrometry was used to study the corrosion inhibitor Irgamet®39 on the surface of copper treated in insulating oils and the effect of temperature changes, by means of temperature programmed desorption experiments under vacuum, on metal coverage. Four commercial oils, both corrosive and non-corrosive, showed no significant influence on the stability of the tolyltriazole layer and the energy of its main desorption event from copper was calculated around 100 kJ mol−1. Finally, an example of ion imaging as diagnostic tool to track the distribution of corrosion inhibitor and by-products in decommissioned or failed power transformers is described.

•Effect of [DBDS], time, air and paper-Cu proximity on CuxS deposition was studied.•XPS and EDX revealed deposition of CuxS in paper increased with time or [DBDS].•O2 was observed to have a key role in CuxS displacement from the conductor surface.•A bifurcated pathway for CuxS deposition in oil-immersed equipment is proposed.XPS and EDX were used to study CuxS deposition in Kraft insulating paper obtained from ageing paper samples in contact with a copper sheet, in mineral oil containing dibenzyl disulphide (DBDS). Qualitative and quantitative evidence of CuxS were obtained from bulk and surface analyses of insulating paper provided by the different depth resolution of the techniques used. The influence of [DBDS], oxygen, time, and Cu-paper contact upon the formation and mobilisation of CuxS were studied. A contact-based mechanism to explain CuxS contamination on paper and its displacement was proposed. The role of O2 in enhancing CuxS displacement was also investigated.

The mechanism of the 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) mediated oxidation of benzyl alcohol in alkaline tert-butanol/water mixtures has been investigated in order to understand the preferred conditions for the mediated oxidation of alcohols in an electrochemical microflow reactor. It is shown that TEMPO and the corresponding hydroxylamine both undergo facile oxidation to the oxoammonium ion at the potential and pH used for the mediated oxidation although the hydroxylamine/TEMPO couple is electrochemically irreversible. The initial reaction between the oxoammonium ion and benzyl alcohol is a rapid reaction but the overall rate of the catalytic cycle, and hence the rate of conversion of alcohol to aldehyde, is determined by a deprotonation step of an intermediate formed in this reaction. The mediated oxidation is never mass transport controlled with respect to the alcohol but the rate of the reaction increases with pH. The oxoammonium ion also reacts with hydroxide and hence the selection of pH for electrosynthesis is a compromise between the increased rate of the catalytic cycle and the loss of mediator due to reaction of the oxoammonium ion with hydroxide as the pH is increased. At a pH of ∼11.5, the rate of the conversion to benzaldehyde is high enough for the reaction to be synthetically useful and much of the TEMPO can be recovered after electrolysis.

A single channel microfluidic electrolysis cell being developed for application alongside other routine microfluidic operations in the laboratory has been applied to the methoxylation of N-formylpyrrolidine. It is shown that very high conversions (≫90%) in a single pass can be achieved and it is possible to obtain several grams of product per hour with a good selectivity in optimised conditions.