- Nitration of deactivated aromatic compounds via mechanochemical reaction
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A variety of deactivated arenes were nitrated to their corresponding nitro derivatives in excellent yields under high-speed ball milling condition using Fe(NO3)3·9H2O/P2O5 as nitrating reagent. A radical involved mechanism was proposed for this facial, eco-friendly, safe, and effective nitration reaction.
- Wu, Jian-Wei,Zhang, Pu,Guo, Zhi-Xin
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supporting information
(2021/05/05)
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- 6MNEP: A molecular cation with large hyperpolarizability and promise for nonlinear optical applications
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Molecular organic crystals are strategically designed for nonlinear optical applications using push-pull chromophores as the core feature. In this approach, electron-donating and accepting groups are connected through a π-conjugated bridge to obtain planar molecules with high hyperpolarizability. However, the non-centrosymmetric packing that is required for nonlinear optical (NLO) applications is a critical challenge that must be addressed to design useful materials. In this article, we present the new organic cation 6MNEP that shows a large hyperpolarizability and can be crystallized in ideal non-centrosymmetric structures for NLO applications, when paired with T and 4NBS anions. The 6MNEP cation was obtained by extending the conjugation length of already existing chromophores. We compare the 6MNEP crystals with other crystals that also have cations with extended conjugation lengths, but result in centrosymmetric crystal structures. Using the effective hyperpolarizability, we found 6MNEP-T and 6MNEP-4NBS to have 1.6 to 2.5 times larger macroscopic nonlinearities than benchmark NLO organic crystals. Additionally, the significantly lower absorption wavelength compared with other state-of-the-art crystals make 6MNEP-T and 6MNEP-4NBS promising materials for NLO applications like intense terahertz generation.
- Bloxham, Joseph C.,Brock, Daniel J.,Jackson, Erika W.,Johnson, Jeremy A.,Kenney, Karissa C.,Michaelis, David J.,Smith, Stacey J.,Valdivia-Berroeta, Gabriel A.,Wayment, Adam X.
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supporting information
p. 11079 - 11087
(2020/09/09)
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- Copper-Catalyzed Multicomponent Reaction of DABCO·(SO2)2, Alcohols, and Aryl Diazoniums for the Synthesis of Sulfonic Esters
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A Cu-catalyzed multicomponent cascade reaction of DABCO·(SO2)2 (DABSO), alcohol, and aryl diazonium tetrafluoroborate was developed which afforded sulfonic esters in moderate to good chemical yields. In this reaction, the SO2 surrogate DABSO was used for the first time in the synthesis of sulfonic aliphatic esters. This multicomponent reaction was carried out under mild conditions and tolerated a wide range of substrates, which provides a new and efficient strategy for the synthesis of sulfonic esters.
- Wang, Yang,Deng, Lingling,Deng, Yu,Han, Jianlin
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p. 4674 - 4680
(2018/04/26)
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- Inscribing the perimeter of the PagP hydrocarbon ruler by site-specific chemical alkylation
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The Escherichia coli outer membrane phospholipid:lipid A palmitoyltransferase PagP selects palmitate chains using its β-barrel-interior hydrocarbon ruler and interrogates phospholipid donors by gating them laterally through an aperture known as the crenel. Lipid A palmitoylation provides antimicrobial peptide resistance and modulates inflammation signaled through the host TLR4/MD2 pathway. Gly88 substitutions can raise the PagP hydrocarbon ruler floor to correspondingly shorten the selected acyl chain. To explore the limits of hydrocarbon ruler acyl chain selectivity, we have modified the single Gly88Cys sulfhydryl group with linear alkyl units and identified C10 as the shortest acyl chain to be efficiently utilized. Gly88Cys-S-ethyl, S-n-propyl, and S-n-butyl PagP were all highly specific for C12, C11, and C10 acyl chains, respectively, and longer aliphatic or aminoalkyl substitutions could not extend acyl chain selectivity any further. The donor chain length limit of C10 coincides with the phosphatidylcholine transition from displaying bilayer to micellar properties in water, but the detergent inhibitor lauryldimethylamine N-oxide also gradually became ineffective in a micellar assay as the selected acyl chains were shortened to C10. The Gly88Cys-S-ethyl and norleucine substitutions exhibited superior C12 acyl chain specificity compared to that of Gly88Met PagP, thus revealing detection by the hydrocarbon ruler of the Met side chain tolerance for terminal methyl group gauche conformers. Although norleucine substitution was benign, selenomethionine substitution at Met72 was highly destabilizing to PagP. Within the hydrophobic and van der Waals-contacted environment of the PagP hydrocarbon ruler, side chain flexibility, combined with localized thioether-aromatic dispersion attraction, likely influences the specificity of acyl chain selection.
- Khan, M. Adil,Moktar, Joel,Mott, Patrick J.,Vu, Mary,McKie, Aaron H.,Pinter, Thomas,Hof, Fraser,Bishop, Russell E.
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experimental part
p. 9046 - 9057
(2011/11/04)
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- Synthesis of alkyl sulfonates from sulfonic acids or sodium sulfonates using solid-phase bound reagents
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An efficient and selective method for the synthesis of sulfonic esters from sulfonic acids or sodium sulfonates using polymer-bound primary triazenes based upon the T2* linker has been developed. The purities of the esters obtained are usually greater tha
- Vignola, Nicola,Dahmen, Stefan,Enders, Dieter,Br?se, Stefan
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p. 7833 - 7836
(2007/10/03)
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- Bimolecular Nucleophilic Substitution (SN2) Reactions of Neopentyl Arenesulfonates with Anilines and Benzylamines in Methanol
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Bimolecular nucleophilic substitution (SN2) reactions of neopentyl arenesulfonates with anilines and benzylamines in methanol at 55.0 deg C are reported.The tightness of the transition state (TS) is similar to that for other typical SN2 processes at a primary alkyl carbon centre based on the magnitude of the cross-interaction constant ρxz (0.30) between the substituents in the nucleophile (X) and leaving group (Z).The TS variation is in accord with that predicted by the potential energy surface diagram, which in turn is consistent with the positive sign of ρxz; a later TS is obtained with a weaker nucleophile and nucleofuge.Taft's polar substituent constant, ?*, for the trimethylsilyl group is estimated to be -0.48 by using a factor of 1.875 for the fall-off of ?* from the tert-butyl to the neopentyl group and extrapolating from the experimental Taft plot.
- Koh, Han Joong,Lee, Hai Whang,Lee, Ikchoon
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p. 253 - 258
(2007/10/02)
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- Stoichiometric Solvation Effects. Part 2. A New Product-Rate Correlation for Solvolyses of p-Nitrobenzenesulfonyl Chloride in Alcohol-Water Mixtures
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For reactions involving nucleophilic attack in alcohol-water mixtures, a linear relationship between the reciprocal of product selectivities (S) and the molar ratios of alcohol and water solvents can be derived, if it is assumed that the reactions are second-order in protic solvent (e.g., with one molecule of solvent acting as a nucleophile and the other as a general base).The relationship (1/S = (slope)(/) + intercept) fits the products of solvolyses of p-nitrobenzenesulfonyl chloride in aqueous ethanol and methanol at 25 deg C (determined by refrigerated RP-HPLC) within the range from water to 80percent v/v alcohol-water.From the slopes and intercepts of these product plots and the one observed rate constant for hydrolysis in pure water, the observed first-order rate constants in alcohol-water mixtures up to 90percent (v/v) can be calculated satisfactority, further supporting the validity of the derived linear relationship; the kinetic model includes three thrid-order rate constants: kww, where water acts as both nucleophile and general base; kwa, water acts as a nucleophile and alcohol acts as a general base; kaw, alcohol acts as a nucleophile and water acts as a general base.Inclusion of a fourth rate-constant, kaa, where the alcohol acts as a nucleophile and a second molecule of alcohol acts as a general base, is necessary to account for solvolyses in 90-99percent alcohol-water; kaa can be calculated from the observed first-order rate constants in pure alcohols.Independent values of kaw and kwa can be obtained from kaa and the slopes and intercepts of linear relationships between S and the molar solvent ratio / within the range 90-99percent alcohol-water.The dominant effect of solvent stoichiometry and the absence of other substantial medium effects is confirmed by the approximately constant third-order rate constants, calculated from the observed first-order rate constants in acetonitrile-, acetone- and dioxane-water mixtures.
- Bentley, T. William,Jones, Robert O.,Koo, In Sun
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p. 753 - 760
(2007/10/02)
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- Perchlorate Esters. Part 3. Correlation of the Rates of Reaction of Arenesulphonate Ions with Methyl Perchlorate in Acetonitrile
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Second-order rate coefficients for the reactions of acetonitrile solutions of tetra-n-butylammonium benzensulphonate and seven meta- and para-substituted derivatives with methyl perchlorate, at 0.3 deg C lead to a Hammet ρ value (-1.10 +/- 0.04) essentially identical to those previously reported for reactions with other powerful methylating agents.When silver ion is substituted for tetra-n-butylammonium ion, the second-oreder rate coefficients become concetration dependent and the fall of with increasing salt concetration can be rationalised on the basis of only free anions being reactive.The calculated degrees of dissociation are applied tothe previously studied silver0ion assisted reaction of silver toluene-p-sulphonate with methyl iodide.
- Kevill, Dennis N.,Lin, Gloria Meichia L.,Bahari, Mohd S.
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- CORRELATION OF THE RATES OF REACTION OF ARENESULFONATE IONS WITH THE TRIMETHYLOXONIUM ION IN ACETONITRILE
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The kinetics of the reactions between trimethyloxonium hexafluorophosphate and a series of tetra-n-butylammonium arenesulfonates have been studied in acetonitrile at -23.4 deg C.With the oxonium salt concentration at about 0.01 M, two series of runs were carried out; Hammett plots of the second-order rate coefficients led to ρ values of -1.18 +/- 0.04 for 0.04 M arenesulfonate salt and -1.07 +/- 0.02 for 0.16 M arenesulfonate salt.Solvolysis kinetics for the trimethyloxonium ion in acetonitrile are also reported.
- Kevill, Dennis N.,Lin, Gloria Meichia L.,Wang, An
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p. 715 - 717
(2007/10/02)
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