Simultaneous Syntheses Research Articles

Deactivation of macroporous ion-exchange resins by acetonitrile and inhibition by water in the simultaneous synthesis of ethyltert-butyl ether (ETBE) andtert-amyl ethyl ether (TAEE)

The deactivating effect of acetonitrile (ACN) and ACN/water mixtures on the feed stream has been investigated for the simultaneous syntheses of ethyltert-butyl ether andtert-amyl ethyl ether over Amberlyst™35 and Purolite®CT-275 ion-exchange resins.

Kinetics of the simultaneous syntheses of ethyl tert-butyl ether (ETBE) and butyl tert-butyl ether (BTBE) over AmberlystTM 35

The kinetics of the simultaneous syntheses of ethyl tert-butyl ether (ETBE) and butyl tert-butyl ether (BTBE) over Amberlyst™ 35 (A35) has been studied at 315–353 K in the liquid phase. Different kinetic modeling approaches—namely, empirical power-law modeling, mechanistic modeling based on Langmuir-Hinshelwood-Hougen-Watson (LHHW) and Eley-Rideal (ER) formalisms, and information-based modeling—have been compared. Empirical kinetic equations yield optimal quality of the fit, whereas mechanistic equations can explain the mechanisms of the studied reactions. The best mechanistic equation for both reactions corresponds to an ER-type mechanism in which an alcohol molecule (ethanol or 1-butanol) is adsorbed on one active site and reacts with isobutene from solution to produce the corresponding adsorbed ether molecule (ETBE or BTBE), which desorbs. A model built based on previous data has been used to check the validity of the inferred mechanism, while significantly reducing the number of adjustable parameters in the model.

Ancient pigment to treasure: Prussian blue as a cheap solid cyanide/nitrogen dual-source affording the high-yield syntheses of pricey endohedral clusterfullerenes

Prussian blue was applied for the first time as a cheap solid cyanide/nitrogen dual-source, affording simplified yet high-yield simultaneous syntheses of novel dysprosium-based metal cyanide clusterfullerenes and metal nitride clusterfullerenes.

Joint Multi‐Frequency Beam Shaping and Steering via Space–Time‐Coding Digital Metasurfaces

AbstractDigital programmable metasurfaces provide a very powerful and versatile platform for implementing spatio‐temporal modulation schemes that are of great interest within the emerging framework of space–time metastructures. In particular, space–time‐coding digital metasurfaces have been successfully applied to advanced wavefront‐manipulations in both the spatial and spectral domains. However, conventional space–time‐coding schemes do not allow the joint syntheses of the transmission/scattering angular responses at multiple frequencies, which are potentially useful in a variety of applications of practical interest. Here, a strategy is put forward to lift this limitation, thereby enabling joint multi‐frequency beam shaping and steering, that is, the independent and simultaneous syntheses of prescribed scattering patterns at given harmonic frequencies. The proposed approach relies on a more sophisticated space–time coding, with suitably designed, and temporally intertwined coding sub‐sequences, which effectively disentangles the joint multi‐frequency syntheses. The power and versatility of the approach are illustrated via a series of representative application examples, including multi‐beam, diffuse‐scattering, and orbital‐angular‐momentum patterns. Theoretical predictions are experimentally validated by means of microwave measurements. The outcomes of this study hold promising potentials for applications to future imaging, information, and mobile‐communication systems.

Tough, Transparent, Photocurable Hybrid Elastomers.

We investigated polydimethylsiloxane/poly(methyl methacrylate) (PDMS/PMMA) interpenetrating polymer networks (IPNs) by both sequential and simultaneous syntheses. In the sequential IPN, the PDMS network was first thermally cured after which methyl methacrylate was swelled in and UV photopolymerized in situ. The simultaneous IPN consists of a one-pot, single-step UV cure of both components. Pure shear fracture and tensile tests were used to extract the Young's modulus, critical fracture strain, and fracture energy of the materials at varying PMMA fractions (up to 50 wt %). At high PMMA fractions, a maximum increase in Young's modulus (42×) and fracture energy (21×) was observed with little sacrifice in the optical properties and the extensibility of notched samples. The Krieger-Dougherty model for particle reinforcement was fit to the modulus data as a function of the PMMA fraction and showed good agreement. The optical properties and microstructure of the IPNs were investigated by UV-visible light transmission, small-angle X-ray scattering (SAXS), and atomic force microscopy (AFM). As the weight fraction of PMMA increased, the simultaneous IPN became less transparent, while the sequential material showed the opposite trend. In the sequential IPN, the minority phase size decreased with increasing PMMA fraction, while it was constant for the simultaneous IPN. Therefore, it was concluded that the sequential IPN transparency is controlled by the size of the PMMA domains, but the simultaneous IPN transparency is controlled by the PMMA fraction. SAXS and AFM also showed evidence of bicontinuous network formation in the simultaneous IPN, which may affect the optical and mechanical properties.

Adolescent Mental Health and Risky Sexual Behavior: A Canadian Perspective

lists, expert consultation, and conference abstracts. Eligible studies focused on pediatric and adolescent oncology patients or survivors, their parents, and/or pediatric oncology providers and their knowledgeof, beliefs about, orattitudes toward fertility preservation aftera cancer diagnosis. Studies were assessed for methodological quality, datawas extracted using a standardized form, and synthesized using the Cochrane guidelines for multi-level, simultaneous syntheses of quantitative and qualitative data. Results: 1233 papers were identified and 36 were included in the final review. 24 studies provided quantitative data (patients: 8, parents: 4, providers: 7, multiple perspectives: 5). 11 studies were qualitative (patients: 7, parents: 0, providers: 3, multiple perspectives: 2). The majority of cancer patients wanted information about treatment related fertility effects and fertility preservation options early in their course of their cancer treatment. Patients recalled receiving this information 30-87% of the time. A higher proportion of patients had heard about fertility issues before treatment in later studies. Many patients (35-64%) were dissatisfied with the information received and identified ways of improving the provision of fertility preservation information. Examples include offering options for parental involvement in initial discussions and offering continued support for fertility preservation decision-making before, during, and after cancer treatment. Parents of pubertal and pre-pubertal cancer patients find many fertility preservation options acceptable despite being experimental, especially if they do not cause a delay in treatment. Providers are aware of the importance of fertility issues for their patients and their families, they are knowledgeable about fertility preservation options, and identify age, pubertal status, critical illness, and uncertainty as potential barriers to communication about and referral for fertility preservation services. Conclusions: Adolescent oncology patients and their parents desire candid and timely fertility preservation related information and referral for fertility preservation procedures. Providers are aware of fertility preservation options and resources, but identify systemrelated and personal barriers to discussionswith adolescent patients and families regarding fertility preservation. Future research should focus on patients and families to determine the optimal setting, method, and delivery of fertility preservation related information. Sources of Support: None.

Synthesis and Morphogenesis of Organic and Inorganic Polymers by Means of Biominerals and Biomimetic Materials

We have studied the simultaneous synthesis and morphogenesis of polymer materials with hierarchical structures from nanoscopic to macroscopic scales. The morphologies of the original materials can be replicated to the polymer materials. In general, it is not easy to achieve the simultaneous synthesis and morphogenesis of polymer material even using host materials. In the present work, four biominerals and three biomimetic mesocrystal structures are used as the host materials or templates and polypyrrole, poly(3-hexylthiopehene), and silica were used as the precursors for the simultaneous syntheses and morphogenesis of polymer materials. The host materials with the hierarchical structure possess the nanospace for the incorporation of the monomers. After the incorporation of the monomers, the polymerization reaction proceeds in the nanospace with addition of the initiator agents. Then, the dissolution of the host materials leads to the formation and morphogenesis of the polymer materials. The scheme of the replication can be classified into the three types based on the structures of the host materials (types I-III). The type I template facilitates the hierarchical replication of the whole host material, type II mediates the hierarchical surface replication, and type III induces the formation of the two-dimensional nanosheets. Based on these results, the approach for the coupled synthesis and morphogenesis can be applied to a variety of combinations of the templates and polymer materials.

Total synthesis of cucurbitoside-like phenolic glycosides by double fluorous and acyl mixture synthesis

The first and simultaneous total syntheses of cucurbitosides A, B, G, and I, seguinosides C and D, and two unnatural analogs were achieved using the technique of fluorous mixture synthesis. The eight precursors of cucurbitoside-like phenolic glycosides were prepared by glycosylation of a mixture of two glucopyranosyl acceptors bearing different fluorous benzyl groups with a mixture of four apiofuranosyl donors bearing benzoyl, 3-methylbutyryl, 4-benzyloxybenzoyl, and 4-nitrobenzoyl groups, followed by a single run of HPLC with serially connected Fluophase ® RP and Inertsil ® ODS-3 columns. Finally, the individual pure disaccharide precursors were detagged to yield the eight cucurbitoside-like phenolic glycosides.

One hundred years of peptide chemistry

Emil Fischer is considered to be the founding father of the field of peptide chemistry and originator of the term peptide. In the beginning of the 20th century, Fischer had a clear vision to foresee the day when a protein would be synthesized. Subsequent to this brilliant beginning, progress however was slow for the next 50 years. In 1953, the chemical synthesis of oxytocin by duVigneaud was a landmark achievement. The subsequent decades witnessed the discovery of a vast number of biologically active peptides. The last three decades saw development of multiple simultaneous syntheses, peptide libraries and peptide vaccines. This article is a concise account of the types of peptides discovered and their biological role.

Simultaneous syntheses of polyhydroxyalkanoates and rhamnolipids by Pseudomonas aeruginosa IFO3924 at various temperatures and from various fatty acids

Medium-chain-length polyhydroxyalkanoates (mcl-PHAs) and rhamnolipids produced by Pseudomonas aeruginosa share 3-hydroxyalkanoates (3HAs) as common structural units. Previously, we demonstrated their simultaneous production to share the cultivation cost for the intracellular products, PHAs, with the extracellular products, rhamnolipids. Here, we investigated the effects of temperature and carbon length of fatty acid substrates on the simultaneous production by P. aeruginosa IFO3924. The optimum temperatures for PHA and rhamnolipid syntheses were 30°C and 28°C, respectively, suggesting that the product ratio between these two products can be controlled by changing temperature. After the induction periods, both PHAs and rhamnolipids were produced at constant rates by resting cells. The apparent activation energies were determined as 45kJ/mol for PHA synthesis and 40kJ/mol for rhamnolipid synthesis from Arrhenius plots. These values in a similar level suggest that a common reaction such as β-oxidation before the synthesis of 3HA units is the rate-determining step. PHAs and rhamnolipids synthesized from fatty acids of even-number carbon length (Ceven) consisted of only Ceven-3HAs. By contrast, PHAs and rhamnolipids synthesized from fatty acids of odd-number carbon length (Codd) consisted of not only Codd-3HAs but also Ceven-3HAs. This is the first report to show the incorporation of Codd-3HAs into rhamnolipids.

One-Pot Redox Syntheses of Heteronanostructures of Ag Nanoparticles on MoO3 Nanofibers

A new one-pot redox route has been developed for simultaneous syntheses of Ag nanoparticles on MoO(3) nanofibers. Four different synthetic reactions that have been integrated into the one-pot synthesis include the oxidation of [Na(H(2)O)(2)](0.25)MoO(3) bronze, the reduction of silver ions, and the in situ simultaneous growth of the self-organized Ag nanoparticles and the MoO(3) nanofibers. This new strategy can be generally applicable to grafting various metal nanoparticles on nanofibers for new catalysis-related applications.

Thermodynamics of formation of nitrogen bases and d-ribose from mineral substances in light of the problem of origination of simplest elements of living matter

The paper represents a further development of our hydrate hypothesis of simplest living matter origination (SLMO) from inorganic and simplest organic mineral substances. It is supposed that the sources of SLMO are simplest aliphatic hydrocarbons, niters, and phosphates. Thermodynamic calculations demonstrating a principal possibility for simultaneous syntheses of different nitrogen bases, d-ribose, and desoxy- d-ribose from these source substances are presented. The most probable principal mechanism of SLMO and the principal conditions necessary for realization of the proposed chemism of SLMO in the framework of the proposed mechanism are considered. A principal means for testing the hypothesis is proposed.

A Novel Intramolecular Cyclization Reaction: Facile Solvent-Free Microscale Synthesis Suitable for Rapid Production of Libraries of 3-Amino-1,2,4-Triazines and for Combinatorial Chemistry

A novel intramolecular cyclization reaction is reported, in which various 1,2-bis(amidinohydrazone)s are converted into 3-amino-1,2,4-triazine or its substituted analogues. The reaction is easily carried out at microscale as well as ordinary scale level by heating the appropriate bis(amidinohydrazone) to roughly 200 °C in an inert atmosphere or in vacuo. No solvents or other reagents are needed. The products are easily isolated, being sublimed off from the starting material and forming single crystals. A microscale procedure employing glass ampoules as the reaction vessel is described. The reaction is rapid and offers a facile way of preparing large series of substituted 3-amino-1,2,4-triazines individually in crystalline form for screening purposes. Because large numbers of bis(amidinohydrazone)s have been synthesized for biochemistry and drug development and libraries exist, the present method may be more practical than combinatorial approaches for the production of 3-amino-1,2,4-triazines, as it allows simultaneous individual syntheses. As the reaction is intramolecular, it is probable that the method can also be used also for mixtures of bis(amidinohydrazone)s to produce several triazines in one ampoule. The structure of the products was confirmed by mass, NMR and IR spectroscopy, elemental analyses and comparison with authentic samples. The reaction was studied using five bis(amidinohydrazone)s of aliphatic glyoxals, phenylglyoxal bis(amidinohydrazone) as well as the bis(amidinohydrazone) of 1,2-cyclohexanedione as starting materials. From the compound mentioned last a bicyclic product was obtained. In the case of the unsymmetric starting material ethylglyoxal bis(amidinohydrazone), both possible isomers were formed. The safety of heating the nitrogen-rich starting materials in large-scale syntheses has not been verified.

Experimental Study of the Liquid-Phase Simultaneous Syntheses of Methyl tert-Butyl Ether (MTBE) and tert-Butyl Alcohol (TBA)

Equilibrium constants for the simultaneous liquid-phase syntheses of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) were determined experimentally at 1.6 MPa in the temperature range 313−353 K using initial water/alcohol molar ratios ranging from 0 to 0.7. Experiments were performed in a batch reactor, the initial molar ratio of alcohol/isobutylene was varied from 0.5 to 2. To reach equilibrium, the macroporous sulfonic acid resin CT-275 was used as the catalyst. TBA synthesis reached chemical equilibrium faster than MTBE synthesis. The thermodynamic equilibrium constants and the enthalpy, free energy, and entropy changes of both reactions are reported as functions of temperature. Both systems behave nonideally, and the equilibrium constants were found to agree with those determined separately and reported in the literature. At 298.16 K, the standard molar enthalpy changes are −33.9 ± 4.6 kJ/mol for MTBE synthesis and −38.4 ± 3.4 kJ/mol for TBA synthesis, and the results are compared with literature data.

Liquid-phase peptide synthesis on polyethylene glycol (PEG) supports using strategies based on the 9-fluorenylmethoxycarbonyl amino protecting group: application of PEGylated peptides in biochemical assays.

Stepwise synthetic assembly of polypeptide chains reversibly linked to polyethylene glycol represents a hybrid between traditional solution and solid-phase chemistries and combines the inherent advantages of both approaches. The technical simplicity and scalability of the liquid-phase peptide synthesis method renders it particularly attractive for multiple parallel syntheses, combinatorial approaches and the large-scale preparation of peptides. The versatile protection strategy based on the N alpha-fluorenylmethoxycarbonyl group commonly used in solid-phase peptide synthesis was adapted to the liquid-phase approach. Fluoride ions were used rather than the conventional organic base piperidine for the repetitive amino-deprotection step. Using a range of acid- and base-labile linkers between the polymer and the peptide, it was shown that free and fully side-chain protected peptides can be obtained using our version of the liquid-phase peptide synthesis method. Protocols for simultaneous multiple syntheses requiring a minimum of equipment are presented and the use of polyethylene glycol-bound peptides in biochemical binding and functional assay systems is demonstrated.

An Information Processing Account of Audiational Abilities

Relationships between individual differences in audiation as measured by Gordon's Music Aptitude Profile (MAP) and generic information processing abilities as proposed by Luria were investigated with a sample of primary school children, some of whom were musically gifted. Scores on all three audiational dimensions of tone, rhythm and sensitivity were significantly correlated with successive synthesis, which may indicate a strong dependence of the MAP on short-term memory. Success on the MAP was not as dependent on simultaneous and executive syntheses. Musically gifted subjects were superior on the tests for tone and rhythm, but not generally on tests for musical sensitivity, consistent with the independence of musical sensitivity as a separate construct from conventional musical aptitude. The musical experience of members of the musically gifted group did not contribute to the variance of their MAP results.

Composites of micro- and mesoporous materials: simultaneous syntheses of MFI/MCM-41 like phases by a mixed template approach

In situ formation of the micro- and mesoporous structures MFI and MCM-41 was obtained using a two-template syntheses gel system [C6H13(CH3)3NBr and C14H29(CH3)3NBr]. The mixed phases were obtained by optimizing template concentrations and reaction temperatures. Constant temperature syntheses as well as sequential high/low or low/high temperature strategies were performed successfully. It was found that the relative amounts of the two structures MFI and MCM-41 in the final products can be controlled by varying the ratio of the templates and by tuning the synthesis temperature. Characterization results indicate that phases of varying complexity were obtained.

Experimental Study of the Simultaneous Synthesis of Methyl tert-Butyl Ether and Ethyl tert-Butyl Ether in Liquid Phase

Equilibria constants for the simultaneous liquid-phase syntheses of methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE) were determined experimentally in the temperature range 313−353 K at 1.6 MPa. To achieve etherification equilibria, the macroporous sulfonic acid resin Bayer K-2631 was used as the catalyst. MTBE reached the equilibrium faster than ETBE. The progress of the reactions toward the respective equilibrium was determined using different particle sizes ranging from 0.1 to 1 mm at 50 °C. Catalyst effectiveness factors greater than unity were observed for the particle sizes of 0.4−0.63 mm.

Organic Chemistry on Solid Supports

AbstractUntil recently, repetitive solid‐phase synthesis procedures were used predominantly for the preparation of oligomers such as peptides, oligosaccharides, peptoids, oligocarbamates, peptide vinylogues, oligomers of pyrrolin‐4‐one, peptide phosphates, and peptide nucleic acids. However, the oligomers thus produced have a limited range of possible backbone structures due to the restricted number of building blocks and synthetic techniques available. Biologically active compounds of this type are generally not suitable as therapeutic agents but can serve as lead structures for optimization. “Combinatorial organic synthesis” has been developed with the aim of obtaining low molecular weight compounds by pathways other than those of oligomer synthesis. This concept was first described in 1971 by Ugi.[56f,g,59c] Combinatorial synthesis offers new strategies for preparing diverse molecules, which can then be screened to provide lead structures. Combinatorial chemistry is compatible with both solution‐phase and solid‐phase synthesis. Moreover, this approach is conducive to automation, as proven by recent successes in the synthesis of peptide libraries. These developments have led to a renaissance in solid‐phase organic synthesis (SPOS), which has been in use since the 1970s. Fully automated combinatorial chemistry relies not only on the testing and optimization of known chemical reactions on solid supports, but also on the development of highly efficient techniques for simultaneous multiple syntheses. Almost all of the standard reactions in organic chemistry can be carried out using suitable supports, anchors, and protecting groups with all the advantages of solid‐phase synthesis, which until now have been exploited only sporadically by synthetic organic chemists. Among the reported organic reactions developed on solid supports are Diels–Alder reactions, 1,3‐dipolar cycloadditions, Wittig and Wittig–Horner reactions, Michael additions, oxidations, reductions, and Pd‐catalyzed CC bond formation. In this article we present a comprehensive review of the previously published solid‐phase syntheses of nonpeptidic organic compounds.

Spot-synthesis: an easy technique for the positionally addressable, parallel chemical synthesis on a membrane support

Simultaneous parallel syntheses at distinct positions on a membrane support is exemplified with the preparation of series of predefined, short peptide sequences (1). Cellulose paper sheets are used as absorptive membranes. Peptides are assembled by manual or automated spotting of small aliquots of solutions containing the activated amino acid derivatives onto marked positions on the sheets. The application of this method to rapid epitope analysis is demonstrated.