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Ověření reaktivity flaviniových solí s N- a O-nukleofily pro případnou transformaci boronových kyselin na odpovídající aminy / Verification of flavinium salts reactivity with N- and O-nucleophiles for eventual transformation of boronic acids to corresponding aminesHonskusová, Linda January 2017 (has links)
Presented diploma thesis follows the long-term study running at the Department of Organic Chemistry at the University of Chemistry and Technology Prague in the field of using flavinium salts as catalysts of oxidation reactions. The aim was to verify the reactivity of flavinium salt 13 with different types of O- and N-nucleophiles by monitoring of the corresponding C4a-adducts formation. In the thesis a simple alloxazinium salt 13 and one of the nucleophiles (hydroxylamine 25) were prepared. According to the results obtained from the UV-VIS measurements nucleophile 25 is the only one of the newly tested wchich formed desired C4a-adduct 13d with alloxazinium salt 13. KEYWORDS flavinium salt, nucleophile, C4a-adduct, organocatalysis, IBSE
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Kvantkemisk förutsägelse av regioselektivitet och reaktivitet hos SNAr-reaktioner / Quantum chemical prediction of regioselectivity and reactivity of SNAr reactionsNorstedt, Elias, Åkerlind, Gunnar, Robin, Fredrik, De Verdier, Olof January 2023 (has links)
Multivariate regression of several different quantum chemical descriptors was used to build a model for the reactivity of nucleophilic aromatic substitution reactions, i.e. SNAr reactions, through predictingthe molecular reaction site’s Gibb’s free activation energy (ΔG‡). The datasets used for training provided data of ΔG‡ for several differing halide leaving groups including chloride, bromide, and fluoride. A set of descriptors were tested for the different leaving groups revealing that dissimilar leaving groups are more dependent on certain descriptors than others, meaning each model has to be tailored for the specific leaving groups. Excellent correlations (R2 = 0.93) were achieved between the predicted ΔG‡ and the experimental ΔG‡.The ability of the model to predict regioselectivity in aromatic compounds with multiple leaving groups was tested and successfully predicted the correct regioselectivity through the calculation of ΔΔG‡ in each case tested. However, the model’s validity outside of the training dataset was put into doubt through low R2 values when the model was tested with several external datasets. An unknown factor arose which is speculated to be because of how differing nucleophiles and solvents affect the ΔG‡. One of these tests yielded excellent correlations (R2 = 0.9525) which could be because of similarities between solvents and nucleophiles between the training dataset but a similar factor between predicted ΔG‡ and the experimental ΔG‡ could still be observed.
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