Halothiation as a Method for Oxidation of Primary Halides and Terminal Olefins to Aldehydes

The richly varied reactivity of the aldehyde group frequently imparts pivotal importance to this functionality in organic synthesis. This fact has resulted in the development of several methods for the elaboration of this structural unit from a variety of precursors.² The report delineates the feasibility of two new couplementary approaches which proceed under mild conditions and demonstrate the utility of “halothiation” as applied to the oxidation of primary halides and terminal olefins. We were led to investigate this approach as a direct consequence of our interest in the Ramberg-Bäcklund rearrangement³ where the preliminary step often involves α-chlorination of the sulfide substrate.⁴ Halothiation is defined by us as a three-step transformation involving introduction of an ArS moiety, directed α-chlorination of the resulting sulfide, and hydrolysis. In principle, of course, the ArSCH₂-unit is uniquely an aldehyde synthon and attention is therefore focused specifically on it at this time.     

Donorstabilized Monometaphosphates and Phosphonates- Structure,Bonding, and Reactivity

Abstract

Previoudy we reported on the preparative use of donorstabilized monometaphosphates, Py.PO₂Cl and Py.PS₂Cl[¹]. ³P MAS investigations as well as X-ray single crystal analysis have been carried out. The isotropic chemical shift of the sulfur compound shows the typical downfield shift (106 ppm) with respect to the oxygen compound The chemical shift anisotropy gives additional information. The relative large spans ω (Py.PO₂Cl: 401 ppm, Py.PS₂Cl: 461 ppm) [²] reveal strong deviations from tetrahedral symmetry (ω = 0 ppm) in agreement with the structural data. The values of the skew parametem K (0.64 and 0.71 resp.) reflect the trend to axial symmetry (k = ± l). X-ray diffraction and NMR data suggest a structural model corresponding to a concentration of double bond character on the two P-X bonds. This model is consistent with the extremely short P-X bond length (1.449 Å and 1.921 Å rasp.) as well as the large P-X-P bond angles (126.4°and 123.7° resp.).     

Characterization of Electron Transfer Dissociation in the Orbitrap Velos HCD Cell

Electron transfer dissociation (ETD) is commonly employed in ion traps utilizing rf fields that facilitate efficient electron transfer reactions. Here, we explore performing ETD in the HCD collision cell on an Orbitrap Velos instrument by applying a static DC gradient axially to the rods. This gradient enables simultaneous three dimensional, charge sign independent, trapping of cations and anions, initiating electron transfer reactions in the center of the HCD cell where oppositely charged ions clouds overlap. Here, we evaluate this mode of operation for a number of tryptic peptide populations and the top-down sequence analysis of ubiquitin. Our preliminary data show that performing ETD in the HCD cell provides similar fragmentation as ion trap-ETD but requires further optimization to match performance of ion trap-ETD.      

Physical Properties and Erosion Behavior of Poly(trimethylene carbonate‐co‐ε‐caprolactone) Networks

Form‐stable resorbable networks are prepared by gamma irradiating trimethylene carbonate (TMC)‐ and ε‐caprolactone (CL)‐based (co)polymer films. To evaluate their suitability for biomedical applications, their physical properties and erosion behavior are investigated. Homopolymer and copolymer networks that are amorphous at room temperature are flexible and rubbery with elastic moduli ranging from 1.8 ± 0.3 to 5.2 ± 0.4 MPa and permanent set values as low as 0.9% strain. The elastic moduli of the semicrystalline networks are higher and range from 61 ± 3 to 484 ± 34 MPa. The erosion behavior of (co)polymer networks is investigated in vitro using macrophage cultures, and in vivo by subcutaneous implantation in rats. In macrophage cultures, as well as upon implantation, a surface erosion process is observed for the amorphous (co)polymer networks, while an abrupt decrease in the rate and a change in the nature of the erosion process are observed with increasing crystallinity. These resorbable and form‐stable networks with tuneable properties may find application in a broad range of biomedical applications.

     

At-line bioprocess monitoring by immunoassay with rotationally controlled serial siphoning and integrated supercritical angle fluorescence optics

In this paper we report a centrifugal microfluidic “lab-on-a-disc” system for at-line monitoring of human immunoglobulin G (hIgG) in a typical bioprocess environment. The novelty of this device is the combination of a heterogeneous sandwich immunoassay on a serial siphon-enabled microfluidic disc with automated sequential reagent delivery and surface-confined supercritical angle fluorescence (SAF)-based detection. The device, which is compact, easy-to-use and inexpensive, enables rapid detection of hIgG from a bioprocess sample. This was achieved with, an injection moulded SAF lens that was functionalized with aminopropyltriethoxysilane (APTES) using plasma enhanced chemical vapour deposition (PECVD) for the immobilization of protein A, and a hybrid integration with a microfluidic disc substrate. Advanced flow control, including the time-sequenced release of on-board liquid reagents, was implemented by serial siphoning with ancillary capillary stops. The concentration of surfactant in each assay reagent was optimized to ensure proper functioning of the siphon-based flow control. The entire automated microfluidic assay process is completed in less than 30 min. The developed prototype system was used to accurately measure industrial bioprocess samples that contained 10 mg mL⁻¹ of hIgG.