Susceptibility to Pitting and Environmentally Assisted Cracking of 17-4PH Martensitic Stainless Steel Produced by Laser Beam Melting.

Materials produced by additive manufacturing (AM) often have different microstructures from those obtained using conventional metallurgy (CM), which can have significant impacts on the materials' durability, and in particular, resistance to corrosion. In this study, we were concerned with the susceptibility to pitting and environmentally assisted cracking (EAC) of 17-4PH martensitic stainless steel (MSS). We focused on the evolution from pitting to EAC, and the behaviour of MSS produced by AM was compared with that of its CM counterpart.

The first example of enamine-Lewis acid cooperative bifunctional catalysis: application to the asymmetric aldol reaction.

(-)-Sparteine directed lithiation of N-Boc-pyrrolidine, alkylation with chloromethylboronate pinacol ester and acid-based deprotection provides homoboroproline HX salt in 94% ee, which is then an efficient enamine-type pyrrolidine catalyst in an asymmetric aldol reaction when neutralised and especially when esterified in situ with a tartrate ester, for example, providing 90% ee of the aldol adduct derived from acetone and p-nitrobenzaldehyde.

The influence of oscillations on product selectivity during the palladium-catalysed phenylacetylene oxidative carbonylation reaction.

This paper reports on the influence of oscillations on product selectivity as well as the dynamics of product formation during the palladium-catalysed phenylacetylene oxidative carbonylation reaction in a catalytic system (PdI2, KI, Air, NaOAc in methanol). The occurrence of the pH oscillations is related to PdI2 granularity and the initial pH drop after phenylacetylene addition. To achieve pH and reaction exotherm oscillations regulation of the amount of PdI2 is required, ensuring that the initial pH does not fall significantly below 1 after phenylacetylene addition.

A (-)-sparteine-directed highly enantioselective synthesis of boroproline. Solid- and solution-state structure and properties.

A two-step, direct asymmetric synthesis of the trifluoroacetate ammonium salt of boroproline is reported. (-)-Sparteine-mediated lithiation of N-Boc-pyrrolidine afforded N-Boc-aminoboronic acid in good yield and enantioselectivity as determined by HPLC (pinanediol ester). Deprotection using TFA yielded the ammonium salt; full characterization data are presented, and the structure in aqueous solution and the occurrence of a B-N species are discussed.

The Strecker reaction: kinetic and equilibrium studies of cyanide addition to iminium ions.

Kinetics studies are reported of the reactions of benzylidene benzylamine 4a, and of benzylidene allylamine 4b, with cyanide in aqueous buffers to give the corresponding [small alpha]-aminonitriles. The results allow the calculation of values of rate and equilibrium constants for reaction of the iminium ions formed from 4a and 4b with cyanide ions. These values are compared with those, obtained from the hydrolysis reactions, for reaction of the iminium ions with hydroxide ions and with water.