Efficient isomerization of α-pinene oxide to campholenic aldehyde promoted by a mixed-ring analogue of molybdenocene

The MoIV complex [(eta5-indenyl)(eta5-cyclopentadienyl)Mo(MeCN)2](BF4)2 (1) has been used to promote two acid-catalyzed epoxide ring-opening reactions under ambient conditions. The alcoholysis of styrene oxide in neat ethanol gave 2-ethoxy-2-phenylethanol in quantitative yield within 10 min. The use of an ionic liquid (IL) as cosolvent benefitted catalyst solubility and recycling while not impairing catalytic performance. Complex 1 in 1,2-dichloroethane was effective for the isomerization of alpha-pinene oxide to campholenic aldehyde (CPA), leading to 87% yield at 1 h reaction. The same yield could be achieved within 1 min by using the IL [Choline][NTf2] as solvent. CPA yields at 1 min reached near-quantitative values (98%) upon recycling of the catalyst/IL mixture, demonstrating an unparalleled combination of activity, selectivity and recyclability for this commercially important reaction. Considering the catalytic features of the 1/IL system, a CPA process flow diagram is proposed and compared to patented technology.publishe

What is being measured with p-bearing nmr probe molecules adsorbed on zeolites?

Elucidating the nature, strength, and siting of acid sites in zeolites is fundamental to fathom their reactivity and catalytic behavior. Despite decades of research, this endeavor remains a major challenge. Trimethylphosphine oxide (TMPO) has been proposed as a reliable probe molecule to study the acid properties of solid acid catalysts, allowing the identification of distinct Brønsted and Lewis acid sites and the assessment of Brønsted acid strengths. Recently, doubts have been raised regarding the assignment of the 31P NMR resonances of TMPO-loaded zeolites. Here, it is shown that a judicious control of TMPO loading combined with two-dimensional 1H-31P HETCOR solid-state NMR, DFT, and ab initio molecular dynamics (AIMD)-based computational modeling provides an unprecedented atomistic description of the host-guest and guest-guest interactions of TMPO molecules confined within HZSM-5 molecular-sized voids. 31P NMR resonances usually assigned to TMPO molecules interacting with Brønsted sites of different acid strength arise instead from both changes in the probe molecule confinement effects at ZSM-5 channel system and the formation of protonated TMPO dimers. Moreover, DFT/AIMD shows that the 1H and 31P NMR chemical shifts strongly depend on the siting of the framework aluminum atoms. This work overhauls the current interpretation of NMR spectra, raising important concerns about the widely accepted use of probe molecules for studying acid sites in zeolites.publishe

Digitally Speaking: Human Touch Re-imagined Through Business Email

This study examines the cultural impacts experienced through the exchange of emails in workplace. The impetus of my inquiry was to search beyond the structure and meaning of emails shared in workplace. This study aims to unpack and examine the efforts, intentions, and strategies present amongst senders and receivers of emails in a variety of workplace environments. The framework of this study was largely driven by a qualitative approach with case studies. This research investigates the phenomenological experiences revealed through interviews. The diverse group of interviewees comprised of seven participants, five males and two females, span multiple professional backgrounds including public and private schools, regional businesses, and for-profit national and international enterprises. This study reveals the complexities often inherent in interpersonal communications, and several themes across the interview participants created new levels of awareness to benefit people as they navigate their own communications within the constructs of the email experience. The amount of effort people invest in various email activities, primarily as senders, serves as the beacon for this project. The results of the project indicate that within the construct of email exchanges between people that go beyond the content of the email, there are considerations and intentions such as emotions, alliances, politics, and taxonomies that are not always evident within the content of the email. The data from this study also indicates that the energy and time people devote to writing and reading emails may be grossly misunderstood today

Multinuclear solid-state NMR characterization of the Bronsted/Lewis acid properties in the BP HAMS-1B (H-[B]-ZSM-5) borosilicate molecular sieve using adsorbed TMPO and TBPO probe molecules

The acid properties of a dehydrated borosilicate, HAMS-1B (H-[B]-ZSM-5), including the acid types, strengths, location, and quantities are investigated by means of trialkylphosphine oxides through multinuclear ID/2D MAS NMR experiments. B-11 DQF-STMAS combined with H-1 MAS NMR studies revealed B-OH and distinct Si-OH protons associated with trigonal boron. P-31 NMR spectra of TMPO-treated HAMS-1B reveal three Bronsted and three Lewis acid sites. We have found a number of limitations applying the TMPO/TBPO method to identify internal/external acidity. Therefore, we propose a new approach to unambiguously discriminate external/internal acid sites by treating a pore-free and pore-blocked HAMS-1B zeolite. This method provided unique structural insight regarding the identification of boron species/coordinations associated with Bronsted/Lewis acid sites. Additionally, ICP analysis in tandem with solid-state NMR enabled full assignment of the detected internal/external acid species and the study of their acid strength. Moreover, we identify the nature of TMPO complexes arising from Bronsted/Lewis interactions. (C) 2014 Elsevier Inc. All rights reserved

Boron removal and reinsertion studies in B-10-B-11 exchanged HAMS-1B (H-[B]-ZSM-5) borosilicate molecular sieves using solid-state NMR

Novel atomic-level insight in boron removal and reinsertion into the framework of a HAMS-1B (H-[B]-ZSM-5) borosilicate molecular sieve was obtained by a combination of wet chemistry and one-/twodimensional B-11 solid-state NMR (SSNMR) spectroscopy. Uncalcined HAMS-1B shows only tetrahedral boron. However, three boron species are observed in B-11 SSNMR spectra of as-prepared and then calcined HAMS-1B: tetrahedral framework boron (B-[4](fr)), trigonal framework boron (B-[3](fr)), and non-framework trigonal boron (B-[3](NF)). A picture has emerged as to the origins of these three species. Trigonal boron species are formed via hydrolysis by reaction with the water formed from water release and water formed by oxidation and removal of the template during calcination. The trigonal boron species are readily removed from the framework by slurrying in water or mild acid solutions. Tetrahedral boron remains at a concentration about equal to that in the calcined sieve not slurried, indicating that it is more difficult to remove. The extent of boron removal and reinsertion is pH dependent. We demonstrate that boron is removed to a greater extent at low pH and can be reinserted when pH is increased. Boron reinsertion into the framework is proven by B-11 SSNMR on a series of B-10-B-11 exchanged borosilicate zeolites. We found that when boron is reinserted it enters at higher concentrations (similar to 40% more) as tetrahedral boron, not trigonal boron, thus reversing partial hydrolysis and removal during calcination. (C) 2015 Elsevier Inc. All rights reserved