A new iron(III) halide-promoted aza-Prins cyclization between γ,δ-unsaturated tosylamines and aldehydes provides six-membered azacycles in good to excellent yields. The process is based on the consecutive generation of γ-unsaturated-iminium ion and further nucleophilic attack by the unsaturated carbon−carbon bond. Homoallyl tosylamine leads to trans-2-alkyl-4-halo-1-tosylpiperidine as the major isomer. In addition, the alkyne aza-Prins cyclization between homopropargyl tosylamine and aldehydes gives 2-alkyl-4-halo-1-tosyl-1,2,5,6-tetrahydropyridines as the only cyclic products. The piperidine ring is widely distributed throughout Nature, e.g., in alkaloids,1 and is an important scaffold for drug discovery, being the core of many pharmaceutically significant compounds.2,3 The syntheses of these type of compounds have been extensively studied in the development of new drugs containing six-membered-ring heterocycles.4 Reactions between N-acyliminium ions and nucleophiles, also described as amidoalkylation or Mannich-type condensations, have been frequently used to introduce substituents at the R-carbon of an amine.5 There are several examples that involve an intramolecular attack of a nucleophilic olefin into an iminium cation for the construction of a heterocyclic ring system.6 Traditionally, the use of hemiaminals or their derivatives as precursors of N-acyliminium intermediates has been a common two-step strategy in these reactions.6a Among this type of cyclization is the aza-Prins cyclization,7 which uses alkenes as intramolecular nucleophile. However, cy† X-ray analysis. E-mail address: malopez@ull.es. (1) (a) Fodor, G. B.; Colasanti, B. Alkaloids: Chemical and Biological PerspectiVes; Pelletier, S. W., Ed.; Wiley: New York, 1985; Vol. 23, pp 1-90. (b) Baliah, V.; Jeyarama, R.; Chandrasekaran, L. Chem. ReV. 1983, 83, 379-423. (2) Watson, P. S.; Jiang, B.; Scott, B. Org. Lett. 2000, 2, 3679-3681. (3) Horton, D. A.; Bourne, G. T.; Smythe, M. L. Chem. ReV. 2003, 103, 893-930. (4) Buffat, M. G. P. Tetrahedron 2004, 60, 1701-1729 and references therein. (5) Speckamp, W. N.; Moolenaar, M. J. Tetrahedron 2000, 56, 3187- 3856 and references therein. (6) (a) Hiemstra, H.; Speckamp, W. N. In ComprehensiVe Organic Synthesis; Trost, B. M., Fleming, O., Heathcock, C. H., Eds.; Pergamon: New York, 1991; Vol. 2, pp 1047-1081. (b) Speckamp, W. N.; Hiemstra, H. Tetrahedron 1985, 41, 4367-4416. (7) (a) Dobbs, A. P.; Guesne, S. J. J.; Hursthouse, M. B.; Coles, S. J. Synlett 2003, 11, 1740-1742. (b) Dobbs, A. P.; Guesne, S. J. J.; Martinove, S.; Coles, S. J.; Hursthouse, M. B. J. Org. Chem. 2003, 68, 7880-7883. (c) Hanessian, S.; Tremblay, M.; Petersen, F. W. J. Am. Chem. Soc. 2004, 126, 6064-6071 and references therein. (d) Dobbs, A. P.; Guesne, S. J. Synlett 2005, 13, 2101-2103. ORGANIC

Iron-Catalyzed Reactions in Organic Synthesis

https://web.itu.edu.tr/okayo/pdf/00review.pdf

Macroporous copolymer networks

A Renaissance in Living Cationic Polymerization

https://www.pcr.ugent.be/Publications/artikelsPCR/Progress%20in%20polymer%20science/TalhaGokmen2011.pdf

Porous Polymer Particles - A Comprehensive Guide to Synthesis, Characterization, Functionalization and Applications

Soil stabilization is a technique to improve the engineering and geotechnical properties of soils such as mechanical strength, permeability, compressibility, durability and plasticity. Much has been learned about soil stabilization techniques and additives over the past century. The state of the practice in stabilization techniques and challenges is presented with a discussion. Moreover, available studies regarding the effects of various types of stabilizing agents on the engineering and geotechnical properties of stabilized soils are reviewed here. These stabilizing agents include both calcium-based and non-calcium-based additives. Eco-friendly additives as alternative materials to conventional stabilizing agents are also discussed in this paper. In addition, the problems associated with the presence of disruptive salts and sulfate as well as the techniques to overcome these problems in soil stabilization projects are reviewed.

Soil and clay stabilization with calcium- and non-calcium-based additives: A state-of-the-art review of challenges, approaches and techniques

Composites of styrene-butadiene rubber were prepared with three different types of lead oxide, namely, monolead oxide (PbO), lead dioxide (PbO 2 ), and red lead oxide (Pb 3 O 4 ). Concentrations of Pb 3 O 4 ranging between 17 and 88 wt% were utilized, whereas 87 wt% was used for PbO and PbO 2 . The prepared composites were investigated for their gamma radiation shielding properties. Moreover, physical and mechanical properties, and electrical conductivity were measured for both the unirradiated and irradiated composites. The highest value obtained for the linear absorption coefficient was 0.424 cm −1 for 88% Pb 3 O 4

Styrene–butadiene rubber/lead oxide composites as gamma radiation shields

The emulsion polymerization of vinyl acetate using potassium persulfate and cyclohexanone sodium bisulfite as redox pair initiation system was studied. The rate of polymerization, maximum conversion, and the number of polymer particles produced were found to change with redox initiator, monomer and emulsifier concentrations, and temperature variation. The rate of polymerization was found to be dependent on the initiator, the monomer, and the emulsifier concentrations to the 0.88, 0.22, and 0.20 powers, respectively. The K2S2O8–NaHSO3 redox system was found to decrease maximum conversion and doesn't form a stable emulsion. The apparent arrhenius activation energy (Ea) estimated for the polymerization system was 65.6 kJ/mol. The viscosity average molecular weights for some obtained poly(vinyl acetate) were determined.

Emulsion polymerization of vinyl acetate initiated by potassium persulfate-cyclohexanone sodium bisulfite redox pair system

The polymerization of methyl methacrylate was carried out in water at various concentrations of sodium bisulfite, ferric oxide, and methyl methacrylate at 30, 40, and 50°C. The effect of ferric oxide on the rate of polymerization was studied at 50°C. Rates of polymerization increased in the presence of ferric oxide. For example, the rate of polymerization increased from 3.4 × 10−5 mole/l.-sec to 11.8 × 10−5 mole/l.-sec when the ferric oxide concentration was varied from 0 to 15 g/l. water. The molecular weight of the polymer decreased from an average of 1.4 × 106 in the absence of ferric oxide to 2.8 × 105 when the ferric oxide was present. The variation of molecular weight of the polymers with temperature and conversion was studied. At a fixed conversion of 80%, the average molecular weight decreased from 3.4 × 105 at 30°C to 2.2 × 105 at 50°C. The average molecular weight was also found to increase with increasing monomer and initiator concentrations. It increased from 8.1 × 104 to 5.3 × 105 and from 3.4 × 105 to 8.9 × 105 as the initiator and monomer concentrations increased from 0.01 to 0.05 mole/l. and from 0.235 to 0.705 mole/l., respectively. The apparent energy of activation for the polymerization was found to be 15.6 and 9.7 kcal/mole in absence and in presence of ferric oxide, respectively.

Ferric oxide‐catalyzed polymerization of methyl methacrylate

It was possible to polymerize methyl methacrylate using sulphur dioxide in aqueous media in presence of calcium sulphite or in presence of natural sand. These inorganic materials play a role in the polymerization process as it did not occur in their absence.



Methylmethacrylat konnte in wasrigem Medium mit Schwefeldioxid in Gegenwart von Calciumsulfit oder naturlichem Sand polymerisiert werden. Diese anorganischen Stoffe greifen in den Polymerisationsablauf ein.

Polymerization of methyl methacrylate in the presence of inorganic substances

Sandy, silty, loamy, clayey, and sandy-loamy soils were impregnated with three types of binding materials, namely, urea formaldehyde, phenol formaldehyde, and sodium silicate. Ammonium chloride, hexamethylene tetramine, and sodium fluorosilicate were used as catalysts for the previously mentioned substances, respectively. Some physico-mechanical tests were carried out with the stabilized soils and different parameters affecting the strength, absorption and durability of stabilized soils were studied.



Sandige, schlammige, lehmige, tonige und sandig-lehminge Erden wurden mit derei Arten von Bindemitteln impragniert, namlich mit Harnstoff-Formaldehyd, Phenol-Formaldehyd und Natriumsilicat. Ammoniumchlorid, Hexamethylentetramin und Natriumfluorsilicat wurden hierbei als Katalysatoren benutzt. Einige physikalisch-mechanische Tests wurden mit den stabilisierten Erden ausgefuhrt und verschiedene Parameter, die die Starke, die Absorption und die Haltbarkeit der stabilisierten Erden beeinflussen, wurden untersucht.

Soil stabilization by polymeric materials

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