The Ritter reaction of 1,2-diolmonoesters with nitriles to 1- vic-amido-2-esters proceeds through dioxonium and nitrilium cation intermediates. To provide the basis for the reaction mechanism, novel forms of these cations were isolated, characterized, and studied by spectroscopic methods and single crystal X-ray analysis. Ground and transition state energies were determined both experimentally and theoretically. Taken together, these data suggest that the reaction proceeds via rapid formation of the dioxonium cation 9, followed by rate determining yet reversible ring opening by acetonitrile to the corresponding nitrilium cation 10 (computed Δ G⧧ = 24.7 kcal at 50 °C). Rapid, irreversible hydration of the latter affords the corresponding vic-acetamido ester. Controlled addition of H2O to the dioxonium cation 9 in acetonitrile- d3 results in near-quantitative production of deuterated acetamido ester 13a. Kinetics of this conversion (9 to 13a) are biphasic, and the slow phase is ascribed to either direct cation 9 attack by acetamide to form cation 16 via O-alkylation or by reversible ether formation. Deuterium labeling studies suggest O-alkylated cation 16 does not directly isomerize to N-alkylated cation 18; instead, it reverts to vic-amidoester 13a via the nitrilium pathway. Preliminary results indicate high regioselectivity for primary amide formation in the diol-Ritter sequence.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Organic light-emitting diode (OLED) displays have been an active and intense area of research for well over a decade and have now reached commercial success for displays from cell phones to large format televisions. A more thorough understanding of the many different potential degradation modes which cause OLED device failure will be necessary to develop the next generation of OLED materials, improve device lifetime, and to ultimately improve the cost vs performance ratio. Each of the different organic layers in an OLED device can be susceptible to unique decomposition pathways, however stability toward excitons is critical for emissive layer (EML) materials as well as any layer near the recombination zone. This study will specifically focus on degradation modes within the hole transport layer (HTL) with the goal being to identify the general decomposition paths occurring in an operating device and use this information to design new derivatives which can block these pathways. Through post-mortem analyses of several aged OLED devices, an apparently common intramolecular cyclization pathway has been identified that was not previously reported for arylamine-containing HTL materials and that operates parallel to but faster than the previously described fragmentation pathways.

A class of four-coordinate boron complexes is reported that contain both electron-rich and electron-poor functional groups. Judicious selection of donor and acceptor moieties with the use of a boron atom as a separating node yields charge transfer complexes capable of thermally activated delayed fluorescence (TADF). Complexes were prepared by a modular method providing access to a wide range of emission colors. The singlet (S1) and triplet (TI) energies are independently tuned to achieve a small S-1-T-1 gap. Raising and lowering of S-1 and T-1 states can be predicted using cyclic voltammetry, NTO analysis, and spin density distribution as determined using Density Functional Theory; separation of the hole and electron wavefunction for S-1 excitation and delocalization of spin density distribution in the T-1 state can help in achieving negligible S-1-T-1 gap. Although photoluminescent quantum yields of the boron complexes in a host matrix are less than 65%, OLED device external quantum efficiencies of up to 8.1% have been achieved at a luminance of 1000 cd/m(2). Selection of a boron emitter with a gap of less than 0.01 eV between the singlet and triplet excited state enables the fabrication of a device with low efficiency roll off and long lifetime. (C) 2017 Elsevier Ltd. All rights reserved.

Electrospray ionization (ESI) of solution mixtures often generates complex mass spectra, even following liquid chromatography (LC), due to analyte multiple charging. Multiple charge state distributions can lead to isobaric interferences, mass spectral congestion, and ambiguous ion identification. As a consequence, data interpretation increases in complexity. Several charge reduction mass spectrometry (MS) approaches have been previously developed to reduce the average charge state of gaseous ions; however, all of these techniques have been restricted to direct infusion MS. In this study, synthetic polyols and surfactants separated by liquid chromatography and ionized by positive mode ESI have been subjected to polonium-210 α-particle radiation to reduce the average charge state to singly charged cations prior to mass analysis. LC/MS analysis of 5000 molecular weight poly(ethylene glycol) (PEG5000) generated an average charge state of 5.88+; whereupon, liquid chromatography/electrospray ionization/charge reduction/mass spectrometry (LC/CR/MS) analysis of PEG 5000 generated an average charge state of 1.00+. The PEG5000 results demonstrated a decrease in spectral complexity and enabled facile interpretation. Other complex solution mixtures representing specific MS challenges (i.e., competitive ionization and isobaric ion overlap) were explored and analyzed with LC/CR/MS to demonstrate the benefits of coupling LC to CR/MS. For example, polyol information related to initiator, identity/relative amount of monomer, and estimated molecular weight was characterized in random and triblock ethylene oxide/propylene oxide polyols using LC/CR/MS. LC/CR/MS is a new analytical technique for the analysis of complex mixtures.

ABSTRACT Polyether polyols based on bisphenol‐S were prepared by alkoxylation and compared with analogs based on bisphenol‐A, as well as standard aromatic polyester, and polyether polyols for viscosity and temperature stability. Thermo‐oxidative stability was determined by thermo‐gravimetric analysis, pyrolysis gas chromatography/mass spectroscopy, and evolved gas analysis mass spectroscopy. Incorporation of the sulfone moiety was found to dramatically improve the thermo‐oxidative stability of the neat polyol. Significant char formation was observed with gas phase evolution of flame retardant SO 2 and aromatic sulfone only apparent at about 600 °C. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54 , 2102–2108

An ion of m/z 110.06036 (ion formula [C6H8NO](+); error: 0.32 mDa) was observed in the collision induced dissociation tandem mass spectrometry experiments of protonated N-(3-aminophenyl) benzamide, which is a rearrangement product ion purportedly through nitrogen-oxygen (N-O) exchange. The N-O exchange rearrangement was confirmed by the MS/MS spectrum of protonated N-(3aminophenyl)- O-18-benzamide, where the rearranged ion, [C6H8NO18](+) of m/z 112 was available because of the presence of O-18. Theoretical calculations using Density Functional Theory (DFT) at B3LYP/6-31 g(d) level suggest that an ion-neutral complex containing a water molecule and a nitrilium ion was formed via a transition state (TS-1), followed by the water moleculemigrating to the anilide ring, eventually leading to the formation of the rearranged ion of m/z 110. The rearrangement can be generalized to other protonated amide compounds with electron-donating groups at the meta position, such as, -OH, -CH3, -OCH3, -NH(CH3)(2), -NH-Ph, and -NHCOCH3, all of which show the corresponding rearranged ions inMS/MS spectra. However, the protonated amide compounds containing electron-withdrawing groups, including -Cl, -Br, -CN, -NO2, and CF3, at the meta position did not display this type of rearrangement during dissociation. Additionally, effects of various acyl groups on the rearrangement were investigated. It was found that the rearrangement can be enhanced by substitution on the ring of the benzoyl with electron-withdrawing groups.

•Transport and deposition appear to be controlled by molecular diffusion.•The distribution of deposited material decays exponentially along the sublimation tube.•Separate molecular species deposit independently of one another.

Organic small molecules continue to gain attention for application in light-emitting devices in displays and solid-state lighting. The purification of these materials by sublimation represents a critical obstacle for their high throughput processing. In this work, we find that the purification of the archetypical hole-transporting material N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-benzidine (α-NPD) is controlled by a combination of viscous flow, Knudsen diffusion, and physical vapor deposition. In contrast with other commercially practiced sublimations, steps like diffusion within the solid feed, desorption from the feed particle surface, and mass transfer within the bed of feed particles, do not significantly affect the sublimation rate. This work provides guidelines for the large-scale purification of organic semiconductor materials, and possibly for a broader range of high value small molecule specialty materials. © 2014 American Institute of Chemical Engineers AIChE J , 60: 1347–1354, 2014

This report describes nucleophilic fluorination of 3 and 5-substituted picolinate ester substrates using potassium fluoride in combination with additive promoters. Agents such as tributylmethylammonium or tetraphenylphosphonium chloride were among the best additives investigated giving improved fluorination yields. Additionally, the choice of additive promoters could influence the potential formation of new impurities such as alkyl ester exchange. Other parameters explored in this study include additive stoichiometry, temperature influence on additive degradation, solvent selection, product isolation by solvent extraction, and demonstration of additive recycling.

There is a significant amount of interest and research in seed-oil-derived lubricants because of elevated environmental consciousness among producers and consumers. While slowly making inroads into selected applications, performance deficits at low temperature and poor thermooxidative stability have consistently relegated seed oil derivatives to roles where biodegradability is paramount or where the performance requirements are relatively low. In this article, the structural attributes that result in seed-oil-derived lubricant properties are defined and quantified. Also, the seed oil triglyceride components are segregated, functionalized, and polymerized to provide a lubricant design that allows flexibility in defining the specified viscosity, while providing an improved low-temperature performance and removing the source of thermooxidative instability.

A derivatization procedure has been developed for the improved characterization of fatty alcohol ethoxylate non-ionic surfactants by liquid chromatography/mass spectrometry. The end hydroxyl group of each surfactant species was converted into an oxycarbonylbenzene-2-sulfonic acid group with 2-sulfobenzoic anhydride under mild conditions. The produced sulfonic acid group allows all species, including fatty alcohols and those with less than three ethoxylates, to be uniformly ionized by electrospray ionization (ESI) mass spectrometry. Both acid and base can be used as a mobile phase additive for liquid chromatography without affecting M(n) and average ethoxylate values, although ion intensities are suppressed during the ESI process. The method was used to analyze seven commercial fatty alcohol ethoxylate non-ionic surfactants, and the determined M(n) and EO values were comparable with the results obtained by NMR. The relative ratio of different fatty alcohol based ethoxylates in a sample can also be determined using the summed mass spectral data.

A significant improvement in a process to produce epichlorohydrin through the use of glycerin as renewable feedstock is presented. The glycerin to epichlorohydrin (GTE) process proceeds in two chemical steps. In the first step, glycerin is hydrochlorinated with hydrogen chloride gas at elevated temperature and pressure to a mixture of 1,3-DCH (1,3-dichlorohydrin, 1,3-dichloropropan-2-ol) and 2,3-DCH (2,3-dichlorohydrin, 2,3-dichloropropan-1-ol), using a carboxylic acid catalyst. In the second step, the mixture of dichlorohydrins is converted to epichlorohydrin with a base. This solventless process represents an economically and environmentally advantageous, atom-efficient process to an existing commodity chemical that can employ a renewable resource for its primary feedstock.

A new synthetic route to the Dow AgroSciences early stage sulfonamide herbicide 3-(2-methoxy-4-trifluoromethyl)-N-(5,7-dimethoxy[1,2,4]triazolo[1,5-a]pyrimidin-2-yl)pyridinesulfonamide (pyroxsulam) has been developed. The synthesis is based on formation of the triazole ring as the final step, utilizing the Tisler triazolopyrimidine cyclization. A Tisler cyclization route to 2-amino-5,7-dimethoxy-1,2,4-trazolo[1,5-a]pyrimidine starting with 2-chloro-4,6-dimethoxypyrimidine has also been demonstrated.