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1. Heterogeneous chemistry of methyl ethyl ketone on mineral oxide surfaces: impacts of relative humidity and nitrogen dioxide on product formation

   https://doi.org/10.1039/D3EA00023K  

   Hettiarachchi, Eshani; Grassian, Vicki H. (May 2023, Environmental Science: Atmospheres)

   Despite their atmospheric abundance, heterogeneous and multiphase reactions of carbonyl compounds are poorly understood. In this study, we investigate the surface adsorption and surface chemistry of methyl ethyl ketone (MEK), the second most abundant ketone in the atmosphere, with several mineral oxide surfaces including SiO 2 , α-Fe 2 O 3 and TiO 2 . In particular, the chemistry of MEK with these common components of mineral dust, under both dry and high relative humidity (RH%) conditions, has been investigated. Furthermore, reactions of adsorbed MEK with gas-phase NO 2 were also examined. We show that MEK molecularly and reversibly adsorbs on SiO 2 whereas irreversible adsorption occurs on both α-Fe 2 O 3 and TiO 2 surfaces, followed by the formation of higher molar mass species resulting from dimerization and oligomerization reactions. Isotope labeling experiments confirmed the incorporation of H atoms from surface hydroxyl groups and strongly adsorbed water into these oligomer products. Most interesting is that at 80% RH, oligomer formation on α-Fe 2 O 3 shifts toward a higher relative abundance of MEK tetramer relative to the dimer while on TiO 2 there was no change in product distribution. In the presence of gas-phase NO 2 , MEK undergoes degradation to formaldehyde and acetaldehyde, followed by the formation of aldol condensation products of these aldehydes on the α-Fe 2 O 3 surface. Overall, this study provides mechanistic insights on mineralogy-specific heterogeneous chemistry of a prevalent and atmospherically abundant ketone. 

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2. The partition of organic compounds from water into the methyl isobutyl ketone extraction solvent with updated Abraham model equation

   https://doi.org/10.1080/00319104.2020.1732375  

   Smart, Katherine; Garcia, Estefania; Oloyede, Blessing; Fischer, Rachel; Golden, Teresa D.; Acree, William E.; Abraham, Michael H. (January 2021, Physics and Chemistry of Liquids)

   Experimental water-to-methyl isobutyl ketone partition coefficientshave been determined for 27 different organic solutes based on gaschromatographic measurements. Updated Abraham model correlationswere determined for describing solute transfer into methyl isobutylketone by combining the measured partition coefficient data deter-mined in the present study with published experimental values takenfrom chemical and engineering literature. One hundred nineteen com-pounds were used in determining the revised Abraham model correla-tions. After calculations, the revised mathematical correlations werefound to match the experimental data to within an overall averagestandard deviation of 0.21 log units. 

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3. Measuring bismuth‐210, its parent, and daughter in aquatic systems

   https://doi.org/10.1002/lom3.10352  

   Waples, James T. (February 2020, Limnology and Oceanography: Methods)

   Abstract ²¹⁰Bi (t_1/2: 5.01 d)—the daughter of²¹⁰Pb and parent of²¹⁰Po—has rarely been measured in aquatic systems, and its behavior in the water column is poorly understood. In this article, I present a method for quickly measuring²¹⁰Pb,²¹⁰Bi, and²¹⁰Po in aquatic samples, where (1)²¹⁰Bi and²¹⁰Po are scavenged onto an anion solid‐phase extraction disk within 15 min of pretreating the sample; (2) beta decay of²¹⁰Bi is counted on the disk immediately thereafter; (3)²¹⁰Po is subsequently removed from the disk and redeposited on a copper plate for α‐spectroscopy; and (4)²¹⁰Pb is determined via the ingrowth of²¹⁰Bi. I present decay‐corrected calculations for total, dissolved, and particle‐bound fractions of each nuclide and conclude with an analysis of²¹⁰Pb,²¹⁰Bi, and²¹⁰Po activities in rain,dreissenid(quagga) mussels, and water samples from the Milwaukee Inner Harbor in Lake Michigan. Results show that the loss of lead on the anion solid‐phase extraction disks was negligible (0.2% ± 2.1%; ± 1 SD,n= 4), and the sorption of bismuth was complete (99% ± 2%; ± 1 SD,n= 16). Relative mean absolute deviations of duplicate sample analyses of lake water were 2.4% ± 1.9% for²¹⁰Pb (geometric mean of total sample activity: 3.0 disintegrations per minute [dpm],n= 6), 7.7% ± 5.8% for²¹⁰Bi (geometric mean of total sample activity: 2.6 dpm,n= 8), and 2.7% ± 1.7% for²¹⁰Po (geometric mean of total sample activity: 1.4 dpm,n= 8). 

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4. A chemical dynamics study of the reaction of the methylidyne radical (CH, X ² Π) with dimethylacetylene (CH ₃ CCCH ₃ , X ¹ A _1g )

   https://doi.org/10.1039/D1CP04443E  

   He, Chao; Fujioka, Kazuumi; Nikolayev, Anatoliy A.; Zhao, Long; Doddipatla, Srinivas; Azyazov, Valeriy N.; Mebel, Alexander M.; Sun, Rui; Kaiser, Ralf I. (December 2021, Physical Chemistry Chemical Physics)

   The gas-phase reaction of the methylidyne (CH; X 2 Π) radical with dimethylacetylene (CH 3 CCCH 3 ; X 1 A 1g ) was studied at a collision energy of 20.6 kJ mol −1 under single collision conditions with experimental results merged with ab initio calculations of the potential energy surface (PES) and ab initio molecule dynamics (AIMD) simulations. The crossed molecular beam experiment reveals that the reaction proceeds barrierless via indirect scattering dynamics through long-lived C 5 H 7 reaction intermediate(s) ultimately dissociating to C 5 H 6 isomers along with atomic hydrogen with atomic hydrogen predominantly released from the methyl groups as verified by replacing the methylidyne with the D1-methylidyne reactant. AIMD simulations reveal that the reaction dynamics are statistical leading predominantly to p28 (1-methyl-3-methylenecyclopropene, 13%) and p8 (1-penten-3-yne, 81%) plus atomic hydrogen with a significant amount of available energy being channeled into the internal excitation of the polyatomic reaction products. The dynamics are controlled by addition to the carbon–carbon triple bond with the reaction intermediates eventually eliminating a hydrogen atom from the methyl groups of the dimethylacetylene reactant forming 1-methyl-3-methylenecyclopropene (p28). The dominating pathways reveal an unexpected insertion of methylidyne into one of the six carbon–hydrogen single bonds of the methyl groups of dimethylacetylene leading to the acyclic intermediate, which then decomposes to 1-penten-3-yne (p8). Therefore, the methyl groups of dimethylacetylene effectively ‘screen’ the carbon–carbon triple bond from being attacked by addition thus directing the dynamics to an insertion process as seen exclusively in the reaction of methylidyne with ethane (C 2 H 6 ) forming propylene (CH 3 C 2 H 3 ). Therefore, driven by the screening of the triple bond, one propynyl moiety (CH 3 CC) acts in four out of five trajectories as a spectator thus driving an unexpected, but dominating chemistry in analogy to the methylidyne – ethane system. 

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5. Marangoni-Induced Honeycomb Structures in Spin-Coated Polymer Nanocomposite Films

   https://doi.org/10.1021/acs.jpcb.4c06630  

   Zhang, Aria C; Ohno, Kohji; Composto, Russell J (December 2024, The Journal of Physical Chemistry B)

   This study investigates Marangoni effect-induced structural changes in spin-coated polymer nanocomposite (PNC) films composed of poly(methyl methacrylate)-grafted silica nanoparticles (NPs) and poly(styrene-ran-acrylonitrile). Films cast from methyl isobutyl ketone (MIBK) solvent exhibit distinct hexagonal honeycomb cells with thickness gradients driven by surface tension variations. Atomic force microscopy reveals protruded ridges and junctions at cell intersections, where NP concentration is the highest. Upon annealing at 155 degrees C, NPs segregate to the surface due to their lower surface energy, and the initially protruding features flatten and eventually form depressed channels while maintaining higher NP density than surrounding areas. Time-of-flight secondary ion mass spectrometry corroborated these findings, highlighting enhanced surface segregation of NPs in MIBK films. These defects can be eliminated using methyl isoamyl ketone (MIAK) as a solvent that produces homogeneous films of uniform thickness. This study highlights the impact of the Marangoni effect on the microstructure and surface properties of PNC films, providing insights for enhancing film quality and performance. 

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