Methylenelactide: vinyl polymerization and spatial reactivity effects

• Judita Britner and
• Helmut Ritter

Beilstein J. Org. Chem. 2016, 12, 2378–2389, doi:10.3762/bjoc.12.232

•  1). Since the polymerization kinetics are mainly controlled by steric effects and the polarity of the double bonds, we evaluated the electronic structure of the different monomers via 1H nuclear magnetic resonance (NMR) spectroscopy. As expected, the double bond protons of MLA at 5.77 and 5.56 ppm

• polymerization kinetics of MLA are similar to these of MMA. In contrast, the non-cyclic push–pull type monomers MAA and EAA are both less reactive. This indicates that in addition to steric hindrance, the mobility of the substituents plays an important role in the spatially controlled chain growth reactions. The

• electron densities of the vinyl groups of the used monomers play a minor role with respect to the polymerization kinetics. The higher mobility of the free substituents of the non-cyclic push–pull type monomers MAA and EAA causes a reduced polymerization rate (Figure 1) compared to that of the stiff cyclic

Experimental and theoretical investigations into the stability of cyclic aminals

• Edgar Sawatzky,
• Antonios Drakopoulos,
• Martin Rölz,
• Christoph Sotriffer,
• Bernd Engels and
• Michael Decker

Beilstein J. Org. Chem. 2016, 12, 2280–2292, doi:10.3762/bjoc.12.221

• of these valuable synthetic intermediates and natural products, appropriate conditions have to be chosen and for application as drug molecules their sensitivity towards hydrolysis has to be taken into account. Keywords: hydrolysis; kinetics; molecular mechanics; natural products; quantum mechanics

• shown). This compound did not undergo any decomposition in the tested pH range after 1 h. The stability analyses shown in Figure 3 have to be regarded as snapshots after 1 h of incubation time only. Therefore, the kinetics for this reaction were investigated in greater detail. On the assumption that

Enantioconvergent catalysis

• Justin T. Mohr,
• Jared T. Moore and
• Brian M. Stoltz

Beilstein J. Org. Chem. 2016, 12, 2038–2045, doi:10.3762/bjoc.12.192

• kinetics [18] were employed to elucidate to the overall process. Interestingly, although the observed rate constants (k1 and k2) indicate that bond formation occurs more rapidly from complex 6 (leading to (R)-7), the equilibrium strongly favors the diastereomeric intermediate 5, and the corresponding

• . Enantioconvergent synthesis of phosphines governed by Curtin–Hammett/Winstein–Holness kinetics (TMS = trimethylsilyl, Is = 2,4,6-triisopropylphenyl). Stoltz’ stereoablative oxindole functionalization. Fu’s type II enantioconvergent Cu-catalyzed photoredox reaction. Stereoablative enantioconvergent allylation and

Ionic liquids as transesterification catalysts: applications for the synthesis of linear and cyclic organic carbonates

• Maurizio Selva,
• Alvise Perosa,
• Sandro Guidi and
• Lisa Cattelan

Beilstein J. Org. Chem. 2016, 12, 1911–1924, doi:10.3762/bjoc.12.181

• reported results for the synthesis of esters from the reaction of nitriles and alcohols [48]. 4-(3-Methyl-1-imidazolium)-1-butanesulfonic acid triflate ([HSO3-BMIM][CF3SO3]) has been chosen as a model organocatalyst to explore the kinetics of the transesterification of methyl acetate with ethanol [49][50

Cross-linked cyclodextrin-based material for treatment of metals and organic substances present in industrial discharge waters

• Élise Euvrard,
• Nadia Morin-Crini,
• Coline Druart,
• Justine Bugnet,
• Bernard Martel,
• Cesare Cosentino,
• Virginie Moutarlier and
• Grégorio Crini

Beilstein J. Org. Chem. 2016, 12, 1826–1838, doi:10.3762/bjoc.12.172

• +, Co2+, Cr3+, Ni2+ and Zn2+, respectively. Moreover, it appears that a polymer concentration of 2 g·L−1 is enough to treat an inorganic load of 50 mg·L−1. Thus, for all the following experiments, the polymers were activated and a concentration of 2 g·L−1 was used. Adsorption kinetics Figure 6 shows the

• adsorption kinetics for two solutions containing five metals at 1 mg·L−1 and 10 mg·L−1. For these two concentrations, 100% removal was reached for most species except for Al1 and Cr1 systems, which reached a state of dynamic equilibrium. However, the adsorption time changed with the concentration and with

• the metals. At 1 mg·L−1 the adsorption kinetics was fast: in 5 min equilibrium was reached for the metals except for Al3+ (240 min). At 10 mg·L−1 for Co2+, Ni2+ and Zn2+, equilibrium time increased to 30 min, while for Al3+ and Cr3+ it decreased to 30 min. These results were obtained in triplicate

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

• ketones [199]. There are thousands of publications on the Baeyer–Villiger reaction. In the latest reviews published by Krow [195] in 1993 and by Renz and Meunier [185] in 1999, the field of application, the reactivity of substrates, and the reaction kinetics and mechanisms are considered in detail. In the

Organic chemistry meets polymers, nanoscience, therapeutics and diagnostics

• Vincent M. Rotello

Beilstein J. Org. Chem. 2016, 12, 1638–1646, doi:10.3762/bjoc.12.161

• complex behaves differently than either of the two components. A prime example of this synergy is when we showed that nanoparticle–enzyme complexes showed altered substrate selectivity [51], with the particle dictating the enzyme kinetics by acting as a "filter" for substrate and product [47]. Another

Synthesis and characterization of benzodithiophene and benzotriazole-based polymers for photovoltaic applications

• Desta Gedefaw,
• Marta Tessarolo,
• Margherita Bolognesi,
• Mario Prosa,
• Renee Kroon,
• Wenliu Zhuang,
• Patrik Henriksson,
• Kim Bini,
• Ergang Wang,
• Michele Muccini,
• Mirko Seri and
• Mats R. Andersson

Beilstein J. Org. Chem. 2016, 12, 1629–1637, doi:10.3762/bjoc.12.160

• ring) in comparison to PTzBDT-1, not only allows a higher donor content in the blend (enhanced light absorption) but also seems to be crucial in terms of precipitation/segregation kinetics during the deposition/drying process of the active blend, strongly influencing the self-organization, the quality

Experimental and theoretical insights in the alkene–arene intramolecular π-stacking interaction

• Valeria Corne,
• Ariel M. Sarotti,
• Carmen Ramirez de Arellano,
• Rolando A. Spanevello and
• Alejandra G. Suárez

Beilstein J. Org. Chem. 2016, 12, 1616–1623, doi:10.3762/bjoc.12.158

• the π-stacking interaction also affects the equilibrium kinetics. In order to better understand the conformational studies, a crystal of acrylate 6a suitable for X-ray diffraction analysis was obtained (for further information, see Supporting Information File 1). The crystal structure shows the vinyl

On the cause of low thermal stability of ethyl halodiazoacetates

• Magnus Mortén,
• Martin Hennum and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2016, 12, 1590–1597, doi:10.3762/bjoc.12.155

• which implies first order kinetics. All the kinetic measurements made in this study followed the same first order kinetic profile [15] and the data obtained from the kinetic profiles are summarized in Table 1. As a point of reference, the half-lives (t1/2) for the non-stabilized diazo compounds 2

• bimolecular dimerization leading to azines; and 3) a reaction of the diazo compound with the solvent or a reactant prior to nitrogen extrusion. The fact that the decomposition rate of all halodiazoacetates showed first order kinetics and that t1/2 for 2b is independent of its concentration indicates that

Beta-hydroxyphosphonate ribonucleoside analogues derived from 4-substituted-1,2,3-triazoles as IMP/GMP mimics: synthesis and biological evaluation

• Tai Nguyen Van,
• Audrey Hospital,
• Corinne Lionne,
• Lars P. Jordheim,
• Charles Dumontet,
• Christian Périgaud,
• Laurent Chaloin and
• Suzanne Peyrottes

Beilstein J. Org. Chem. 2016, 12, 1476–1486, doi:10.3762/bjoc.12.144

• potential binding sites have been described in the literature [17][18]. According to the X-ray crystallography, kinetics and mutagenesis studies, four effectors have been identified for binding in the effector site 1. The activation of the site 2 is more questionable as solid data is still required to

The hydrolysis of geminal ethers: a kinetic appraisal of orthoesters and ketals

• Sonia L. Repetto,
• James F. Costello,
• Craig P. Butts,
• Joseph K. W. Lam and
• Norman M. Ratcliffe

Beilstein J. Org. Chem. 2016, 12, 1467–1475, doi:10.3762/bjoc.12.143

• hydrolyses. Keywords: FDII; geminal ethers; kinetics; Introduction Our interest in organic dehydrating agents for applications in the aeronautical industry is stimulated by the commercial case for developing a new approach to managing water contamination in jet fuel. The acid-catalysed hydrolysis reactions

• Micromass AutoSpec MS in CI mode using CH4 as the collision gas. HRMS and elemental analysis were performed by the respective services at the School of Chemistry, University of Bristol. Orthoester hydrolysis kinetics. The reacting pair of 2 and 6 has been used here to illustrate a typical procedure

On the mechanism of imine elimination from Fischer tungsten carbene complexes

• Philipp Veit,
• Christoph Förster and
• Katja Heinze

Beilstein J. Org. Chem. 2016, 12, 1322–1333, doi:10.3762/bjoc.12.125

• a first order kinetics as anticipated in the absence of a base. An Eyring–Polanyi plot gives an activation enthalpy of ΔH‡ = 54.5 ± 10.4 kJ mol−1 and an activation entropy of ΔS‡ = –193 ± 30 J mol−1 K−1 (Supporting Information File 1, Figure S25). These values give a Gibbs free energy of activation

The role of alkyl substituents in deazaadenine-based diarylethene photoswitches

• Christopher Sarter,
• Michael Heimes and
• Andres Jäschke

Beilstein J. Org. Chem. 2016, 12, 1103–1110, doi:10.3762/bjoc.12.106

• photochemical properties, in particular their photochromicity, switching kinetics and reversibility, fatigue resistance, and thermostability, were investigated. The main text shows only the analytical data for new pyridyl switch 1b in comparison to the previously published and well-studied switch 2b [43]; all

Efficient syntheses of climate relevant isoprene nitrates and (1R,5S)-(−)-myrtenol nitrate

• Sean P. Bew,
• Glyn D. Hiatt-Gipson,
• Graham P. Mills and
• Claire E. Reeves

Beilstein J. Org. Chem. 2016, 12, 1081–1095, doi:10.3762/bjoc.12.103

• = 1 × 106 tons) [4]. Indeed, although early estimates of isoprene emissions were as high as 1200 Tg C yr−1 [5] these have, in recent years, been revised down to 600 Tg C yr−1 [6]. Be this as it may, a comprehensive understanding of the atmospheric chemistry and kinetics associated with isoprene and

• standards has hindered a comprehensive understanding of IPN climate chemistry, there has been progress in a number of laboratory, field and theoretical studies that have focused on probing their formation, kinetics, yields and decomposition. By way of example, Teng et al. investigated the branching ratio (α

• kinetics of IPN formation, the percentages of individual IPNs generated or how they are synthesised and the products of their decomposition. Answering these important questions requires the combined expertise of synthetic and atmospheric chemists using the former to generate authentic samples of IPNs which

From steroids to aqueous supramolecular chemistry: an autobiographical career review

• Bruce C. Gibb

Beilstein J. Org. Chem. 2016, 12, 684–701, doi:10.3762/bjoc.12.69

• Figure 11 (table) were obtained. To account for this data we built a Michaelis–Menten model that showed how the kinetics of hydrolysis in the presence of octa-acid is dependent on both the equilibria between the free and bound species and the relative rate with which the free esters undergo reaction. The

Art, auto-mechanics, and supramolecular chemistry. A merging of hobbies and career

• Eric V. Anslyn

Beilstein J. Org. Chem. 2016, 12, 362–376, doi:10.3762/bjoc.12.40

• appropriate for the job: valve spring compressors, feeler gauges, socket wrenches, etc. As organic chemists, we propose hypotheses explaining how Mother Nature works, and we have particular experimental tools to test our theories: kinetics, isotope effects, solvent effects, etc. [24]. Reactions with multiple

Amino-functionalized (meth)acryl polymers by use of a solvent-polarity sensitive protecting group (Br-t-BOC)

• Helmut Ritter,
• Monir Tabatabai and
• Markus Herrmann

Beilstein J. Org. Chem. 2016, 12, 245–252, doi:10.3762/bjoc.12.26

• , IR, GPC and DSC methods. The kinetics of the deprotection step was followed by 1H NMR spectroscopy. The solvent polarity and neighboring group effects on the kinetics of deprotection are discussed. Keywords: amino group protection; bromo-tert-butyloxycarbonyl; deprotection; free radical

• . Carpino [8][9][10] and a first practical application in peptide synthesis [11] this protecting group was quasi forgotten. In the present work we report new Br-t-Boc-protected (meth)acrylic monomers and their polymerization through free radical polymerization. The kinetics of Br-t-BOC solvolysis of the

Interactions of cyclodextrins and their derivatives with toxic organophosphorus compounds

• Sophie Letort,
• Sébastien Balieu,
• William Erb,
• Géraldine Gouhier and
• François Estour

Beilstein J. Org. Chem. 2016, 12, 204–228, doi:10.3762/bjoc.12.23

Thermal and oxidative stability of Atlantic salmon oil (Salmo salar L.) and complexation with β-cyclodextrin

• Daniel I. Hădărugă,
• Mustafa Ünlüsayin,
• Alexandra T. Gruia,
• Cristina Birău (Mitroi),
• Gerlinde Rusu and
• Nicoleta G. Hădărugă

Beilstein J. Org. Chem. 2016, 12, 179–191, doi:10.3762/bjoc.12.20

• -crystallization at a 1:1 molar ratio (Table 2). The results of the KFT kinetics indicate that the diffusion of “surface” water is lower in complexes than in commercial β-CD particles and even up to ten times slower for complexes obtained at a 1:1 molar ratio. The diffusion of “strongly-retained” water in

A journey in bioinspired supramolecular chemistry: from molecular tweezers to small molecules that target myotonic dystrophy

• Steven C. Zimmerman

Beilstein J. Org. Chem. 2016, 12, 125–138, doi:10.3762/bjoc.12.14

• consistent with much of the data [45]. Beyond the novelty of the binding mode, we thought these macrocyclic bisintercalators might serve as probes of DNA breathing and further might have particularly slow dissociation kinetics, thereby improving their ability to inhibit enzymatic DNA processing. However

Polydisperse methyl β-cyclodextrin–epichlorohydrin polymers: variable contact time ¹³C CP-MAS solid-state NMR characterization

• Isabelle Mallard,
• Davy Baudelet,
• Franca Castiglione,
• Monica Ferro,
• Walter Panzeri,
• Enzio Ragg and
• Andrea Mele

Beilstein J. Org. Chem. 2015, 11, 2785–2794, doi:10.3762/bjoc.11.299

• but with different absorption properties. The main purpose of the work was to find a suitable spectroscopic descriptor accounting for the different imprinting process in three homogeneous polymeric networks. The polymers were characterized by studying the kinetics of the cross-polarization process

• differences are detectable from the 13C CP-MAS NMR spectra. The study of the kinetics of the cross-polarization process allowed us to determine, for a large collection of C atoms of all the systems, the TCH and T1ρ parameters. A clear-cut physical interpretation of the numerical values derived from our

Learning from the unexpected in life and DNA self-assembly

• Jennifer M. Heemstra

Beilstein J. Org. Chem. 2015, 11, 2713–2720, doi:10.3762/bjoc.11.292

• activities, or just playing with Lego blocks. Conclusion Looking toward to the future of aptamer-based sensors, I feel that there is still much to learn about the thermodynamics and kinetics of sensor assembly and target recognition. Inevitably, many of these discoveries will be made much like those I’ve

Smart molecules for imaging, sensing and health (SMITH)

• Bradley D. Smith

Beilstein J. Org. Chem. 2015, 11, 2540–2548, doi:10.3762/bjoc.11.274

• nanomolar dissociation constants. The rate of macrocycle threading is insensitive to the length of the appended PEG chains. But the threading kinetics are greatly affected by the steric size of the second N-substituent at each end of the squaraine dye, and an N-propyl group produces a perfect mixture of

• ) Two views of the threaded complex highlighting the structural features controlling the threading kinetics and thermodynamics. Acknowledgements First and foremost, I am extremely grateful to all of the students who have worked in my lab over years, and the names of many are listed in the references

Aggregation behaviour of amphiphilic cyclodextrins: the nucleation stage by atomistic molecular dynamics simulations

• Giuseppina Raffaini,
• Antonino Mazzaglia and
• Fabio Ganazzoli

Beilstein J. Org. Chem. 2015, 11, 2459–2473, doi:10.3762/bjoc.11.267

• boundary conditions (PBC). While MM methods involve energy minimizations of the simulated systems with respect to all the atomic coordinates, the MD methods describe the time evolution of the whole system at the chosen temperature, according to Newton’s equation of motion, thus following the kinetics of a

• configurational entropy. On the other hand, taken together the present results in water may provide some clues about the possible kinetics of aggregation: at first there is the fast formation of small clusters comprising few molecules, followed by the further aggregation of these cluster with may add individual