One-pot,one-step,and selective terpolymerization of ethylene oxide,propylene oxide,and COS to copoly(thioether)s with tunable thermal properties

Facile construction of sulfur-rich polymers using readily available raw chemicals is an area aggressively pursued but challenging. Herein we use common feedstocks of ethylene oxide (EO), propylene oxide (PO), and carbonyl sulfide (COS) to synthesize copoly(thioether)s which are traditionally produced from unpleasant and difficult to store episulfides. In this protocol, the EO/COS coupling selectively generates a pure poly(ethylene sulfide) (PES) with melting temperature (T_m) values up to 172°C and high yields up to 98%. The EO/PO/COS terpolymerization leads to the incorporation of soft poly(propylene sulfide) (PPS) and hard PES segments together, affording a random PES-co-PPS copoly(thioether) with the complete consumption of EO and PO. Additionally, by simply varying the EO/PO feeding ratio, the obtained copoly(thioether)s possess tunable thermal properties, T_m values in the range of 76–144°C, and excellent solubility. These copolymerizations are conducted in one-pot/one-step at industrially favored reaction temperatures of 100–120°C using catalysts of common organic bases, suggesting a facile and practical manner. Especially, the copoly(thioether) exhibits high refractive indices up to 1.68 owing to its high sulfur content, suggesting a broad application prospect in optical materials.     

Efficient microwave induced direct α-halogenation of carbonyl compounds

A novel and direct method for the synthesis of α-halocarbonyl compounds using sequential treatment of carbonyl compounds with [hydroxy(tosyloxy)iodo]benzene followed by magnesium halides under solvent-free microwave irradiation conditions is described.     

Liquid-phase noncatalytic butene oxidation with nitrous oxide

The kinetics and mechanism of noncatalytic liquid-phase oxidation of but-1-ene and but-2-ene with nitrous oxide in a benzene solution in the temperature range from 180 to 240°C were studied. Oxidation proceeds via the 1,3-dipolar cycloaddition mechanism to form carbonyl compounds. Both of these reactions occur with close rates and activation energies and have the first orders with respect to the alkene and N₂O. A considerable fraction (39%) of but-1-ene involved in oxidation undergoes cleavage at the double bond yielding propanal and an equivalent amount of methylene, the latter producing ethylcyclopropane and cycloheptatriene. The oxidation of but-2-ene proceeds with a minimum bond cleavage and affords methyl ethyl ketone with 84% selectivity. Regularities of the oxidation of terminal and internal alkenes C₂—C₈ with nitrous oxide were analyzed using the previously published data. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 925–933, April, 2005.     

A novel synthesis of 5-perfluorophenyl 4,5-dihydro-1H-pyrazoles in THF or water

5-Perfluorophenyl 4,5-dihydro-1H-pyrazoles were synthesized from 1,3-dipolar cycloaddition reaction of perfluorobenyl 2,4,6-triisopropylbenzenesulfonylhydrazone and α,β-unsaturated carbonyl compounds or acrylonitrile in THF or water. It was worthy to note that better results were obtained when water was employed as the solvent, which was considered as an effective, economic and environmentally friendly method to synthesize these pyrazole derivatives.     

Rhodium-catalyzed addition of arylstannanes to carbon-heteroatom double bond

The addition of arylstannanes to the carbon-heteroatom double bond in the presence of a catalytic amount of a cationic rhodium complex ([Rh(cod)(MeCN)₂]BF₄) was examined. The reactions of aldehydes, α-dicarbonyl compounds, and N-substituted aldimines with the arylstannanes gave corresponding alcohols, α-hydroxy carbonyl compounds, and amines, respectively. An arylrhodium complex generated by the transmetalation with the arylstannane was probably the active catalytic species.     

Preparation and characterization of poly(amidoamine) dendrimers functionalized with a rhenium carbonyl complex and PEG as new IR probes for carbonyl metallo immunoassay

The first poly(amidoamine) (PAMAM) dendrimers tethered with both (η⁵-cyclopentadienyl) rhenium tricarbonyl (CpRe(CO)₃) units and polyethylene glycol (PEG) chains were prepared and characterized by combining NMR spectroscopy and Fourier-transform IR spectroscopy. Grafting of CpRe(CO)₃ units was achieved by reductive amination of formyl-CpRe(CO)₃ with the peripheral amines of generation 3 and 4 PAMAMs to yield dendrimers labeled with a variable number of CpRe(CO)₃ units, ranging from 8 to 14 for PAMAM-G3 and 17-30 for PAMAM-G4. PEG chains of different lengths were then attached to some of the remaining peripheral amines, and their respective ability to improve the solubility of the metallodendrimers in aqueous buffered media was evaluated. These metallodendrimers represent new infrared probes designed to be coupled to immunological reagents for the amplification of the IR signal in carbonyl metallo immunoassay (CMIA).     

Recent studies on phosphorus-bridging carbonyl derivatives: organophosphorus analogs of aldehydes and ketones

Reactions of disodium tetracarbonylferrate, Na₂Fe(CO)₄, with sterically hindered dialkylaminodichlorophosphines, R₂NPCl₂ (R₂N=diisopropylamino, dicyclohexylamino, and 2,2, 6, 6-tetramethylpiperidino) in diethyl ether lead to the air-stable phosphorus-bridging carbonyl derivatives (R₂NP)₂COFe₂(CO)₆ as the major products. The phosphorus-bridging carbonyl group in (i-Pr₂NP)₂COFe₂(CO)₆ has been found to undergo the following types of reactions: 1)Reduction, 2)Acylation, 3)Extrusion of the carbonyl group. The mechanisms of the reactions have been considered.This work was presented at the Workshop «The Modern Problems of Heteroorganic Chemistry» held on the ship «Nikolai Bauman» during the period May 8–13, 1993.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1858–1867, November, 1993.     

羰基铁催化黄樟油素、丁香酚异构化反应的研究——Ⅰ.异黄樟油素、异丁香酚的合成

本文报道了异黄樟油素、异丁香酚的新合成途径,即在羰基铁光催化下或多核羰基铁加热催化下,使黄樟油素、丁香酚异构化。其转化率几乎是定量的。反应产物经GC,GC/MC分析及UV,IR,NMR,折光率的鉴定,证明合成过程中发生了异构化反应,而且产物以反式异构体为主。