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Mn(II) and Zn(II) Containing Linseed Oil-Based Poly (Ester Urethane) as Protective Coatings
Published in Lionello Pogliani, Suresh C. Ameta, A. K. Haghi, Chemistry and Industrial Techniques for Chemical Engineers, 2020
Eram Sharmin, Manawwer Alam, Deewan Akram, Fahmina Zafar
The reaction occurs both at hydroxylic and carboxylic ends of Lpol. The first step follows addition–elimination reaction at the carbonyl carbon of the carboxylic acid terminated end of Lpol and metal acetate. The reaction results in the incorporation of metal in Lpol backbone. The first step involves addition reaction at carbonyl carbon of Lpol leading to tetrahedral transition state developing partial negative charge on oxygen (from initial trigonal state), followed by the formation of tetrahedral intermediate. The latter then undergoes ejection reaction (of –OH) returning to initial trigonal state resulting in overall nucleophilic acyl substitution by addition-ejection/elimination reaction at the carbonyl carbon of carboxylic acid terminated end of Lpol. The reaction at hydroxylic end occurs by attack on carbonyl carbon of metal acetate, forming metal oxide.17–25
Probing PAH Formation from Heptane Pyrolysis in a Single-Pulse Shock Tube
Published in Combustion Science and Technology, 2023
Alaa Hamadi, Leticia Piton Carneiro, Fabian-Esneider Cano Ardila, Said Abid, Nabiha Chaumeix, Andrea Comandini
Four different C14H10 species are identified and quantified in 2000 ppm heptane pyrolysis, including the dominant phenanthrene (PC14H10), and its isomers, diphenylacetylene (C6H5CCC6H5), 9-methylene-fluorene (C13H8CH2), and anthracene (AC14H10). Reaction pathways leading to C14H10 isomers formation at 1500 K are presented in Figure 6. C6H5CCC6H5 (Figure 3o) and C13H8CH2 (not shown in Figure 3) are the products of the C6H5C2H+C6H5 addition-elimination reaction (Sun et al. 2020). AC14H10 (Figure 3p) is totally formed from C7H5 self-recombination. PC14H10 (Figure 3h) mainly comes from the C7H7 self-recombination and AC14H10 isomerization. Other reaction channels which contribute to PC14H10 formation include: the C7H5 self-recombination, H-assisted isomerization of C6H5CCC6H5 and C13H8CH2, and the reaction of C9H7 with cyclopentadienyl radical (C5H5), which results from the consumption of C5H6 and the addition of C3H3 to C2H2.
An expedient carbon–sulfur bond formation explored through the cellulose sulfonic acid (CSA) catalyzed dithioacetal protection of carbonyl compounds
Published in Journal of Sulfur Chemistry, 2020
With this background in mind, and in continuation of our research to develop greener and convenient routes for important organic transformations [45–47], herewith we wish to report our study on cellulose sulfonic acid (CSA) as an efficient, recyclable, environmentally friendly catalyst for 1,1-dithioacetal protection of the carbonyl group through the addition–elimination reaction of aldehydes or ketones with 1,2-dithiol or 1,3-dithiols (Scheme 1). A diverse range of aldehydes or ketones smoothly underwent the protection reaction to yield the desired products in good to excellent yields.
A DFT study on the addition and abstraction reactions of thiourea with hydroxyl radical
Published in Journal of Sulfur Chemistry, 2018
Mwadham. M. Kabanda, Kemoabetswe R. N. Serobatse
The •OH addition pathway to hydrogen abstraction mechanism is considered to occur initially at the carbon–sulfur double bond [80]. In order to identify the possible initial pre-reactive complex, transition structures and the intermediate structure, a scan of the C1···O5 bond was performed starting from the RCabs optimized adduct. In order to achieve the desired results, we took into consideration the fact that the standard C–O single bond distance has a value of 1.43 Å [59,60]. Figure S4 (https://dx.doi.org/10.1080/17415993.2017.1359269) shows the scan of the C1···O5 bond as obtained using the ωB97X–D/6-31+G(d,p) method. The diagram has three minima, corresponding to C1···O5 bond distances (Å) of 2.93, 2.33 and 1.43. The scan diagram has two maxima corresponding to C1···O5 bond distances (Å) of 2.43 and 1.93. We envisaged that the proper graph corresponding to the C1···O5 bond scan should start with the minimum at a C1···O5 bond distance of 2.33 Å, going through the maximum at a C1···O5 bond distance of 1.93 Å and ending at the minimum structure occurring at a C1···O5 bond distance of 1.43 Å. The minimum obtained at a C1···O5 bond distance of 2.33 Å was optimized separately and considered as the appropriate initial pre-reactive complex structure for the addition reaction; it is denoted throughout the article as RCadd. The maximum occurring at a C1···O5 bond distance of 1.93 Å was optimized to determine its nature as a stationary point. Frequency calculations run on the optimized structure confirmed that it is a saddle point with one imaginary frequency of magnitude 360.0 cm−1; it is therefore a possible TS structure and is denoted as TSadd-1. The minimum occurring at a C1···O5 bond distance of 1.43 Å was also optimized and confirmed to be a true minimum on a potential surface; the optimized structure is considered as the intermediate for the addition–elimination reaction and is denoted throughout the article as IM. IRC calculation was performed to confirm that TSadd-1 connects RCadd and IM; the result of the study is shown in Figure S5 (https://dx.doi.org/10.1080/17415993.2017.1359269).