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1. Heterocyclic Surgery for Isotopic Labeling

   https://doi.org/10.1055/s-0043-1775110  

   Smith, Joel M (September 2024, Synlett)

   Recent developments in the isotopic labeling of heteroarenes may prove to be useful in the realms of biomedical science, materials chemistry, and fundamental organic chemistry. The use of the age-old Zincke reaction, or tactical variants thereof, has become particularly utilitarian in effecting single-atom nitrogen replacement in various azines to generate their desired isotopologues. This chemistry can be synthetically leveraged at an early stage for diversity-oriented heterocyclic labeling of pharmaceuticals and/or natural products. Additionally, given the prevalence of saturated azacycles in biologically relevant molecules, access to these isotopologues becomes relevant through dearomative retrosynthetic analysis from the corresponding 15N-labeled heteroarenes. 

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2. Isotopic Equilibration in Convective Downdrafts

   https://doi.org/10.1029/2022GL098743  

   Torri, Giuseppe (August 2022, Geophysical Research Letters)

   Abstract While it is becoming increasingly clear that stable water isotopologues are important tools in the study of atmospheric convection, many questions remain on how different processes affect them. This work is focused on water vapor isotopes in precipitation‐driven downdrafts. Using idealized simulations, the contributions of rain evaporation and liquid‐vapor equilibration processes are analyzed. It is shown that rain evaporation tends to deplete water vapor isotopes throughout the downdraft's descent, whereas equilibration has a neutral or depleting effect in the first half of the downdraft's life cycle and an enriching one in the second half. The total contribution of the two processes is then discussed, and it is argued that equilibration has an overall small effect compared to rain evaporation. Finally, using two sensitivity experiments, it is shown that the role played by equilibration varies significantly in regimes with different concentrations of cloud condensation nuclei. 

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3. Lithium isotopic fractionation during weathering and erosion of shale

   https://doi.org/10.1016/j.gca.2020.12.006  

   Steinhoefel, Grit; Brantley, Susan L.; Fantle, Matthew S. (February 2021, Geochimica et Cosmochimica Acta)
4. Potassium isotopic fractionation during clay adsorption

   https://doi.org/10.1016/j.gca.2021.04.027  

   Li, Wenshuai; Liu, Xiao-Ming; Hu, Yan; Teng, Fang-Zhen; Hu, Yongfeng (July 2021, Geochimica et Cosmochimica Acta)
5. Controls on Li partitioning and isotopic fractionation in inorganic calcite

   https://doi.org/10.1016/j.gca.2024.07.001  

   Branson, Oscar; Uchikawa, Joji; Bohlin, Madeleine S; Misra, Sambuddha (October 2024, Geochimica et Cosmochimica Acta)

   The δ7Li of marine carbonates has been interpreted as an archive of the evolution of seawater δ7Li, and therefore continental weathering, through geological time. However, little is known about the incorporation of Li into calcium carbonate minerals and, consequently, the controls on Li partitioning (DLi) and isotopic fractionation (Δ7Lisolid-fluid) associated with Li incorporation. Crucially, we lack a fundamental understanding of how Li partitioning and Δ7Lisolid-fluid change in response to the chemical and physical conditions of crystal formation. Here, we present DLi and Δ7Lisolid-fluid data from a series of inorganic calcite precipitation experiments where temperature, and solution pH and dissolved inorganic carbon (DIC) were independently varied. We find DLi values in the range 0.8–1.5 × 10−3, which show no relationship with temperature, a strong positive correlation with pH, and a weak positive correlation with DIC. At face value, these patterns are inconsistent with the results of previous precipitation studies. However, the correlations with pH and DIC are consistent with a strong precipitation rate control on DLi that aligns well with previous data, with a likely secondary influence from the incorporation of Li-HCO30 ion pairs from solution. We find Δ7Lisolid-fluid values in the range −6 to −2 ‰, which show no relationship with temperature or pH, and a weak positive correlation with DIC and crystal precipitation rate. These results do not agree with previously published data. Considered alongside previously published data, we observe no consistent relationship between Δ7Lisolid-fluid and any reported physical or chemical experimental parameter, highlighting the need for substantial further work to determine whether systematic controls on Li isotopic fractionation exist in carbonate minerals, and whether they may be environmentally significant. 

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