Redox initiated cationic polymerization of oxetanes

3,3‐Disubstituted oxetane monomers were found to undergo rapid, exothermic redox initiated cationic ring‐opening polymerization in the presence of a diaryliodonium or triarylsulfonium salt oxidizing agent and a hydrosilane reducing agent. The redox reaction requires a noble metal complex as a catalyst and several potential catalysts were evaluated. The palladium complex, Cl₂(COD)Pd^II, was observed to provide good shelf life stability while, at the same time, affording high reactivity in the presence of a variety of hydrosilane reducing agents. A range of structurally diverse oxetane monomers undergo polymerization under redox cationic conditions. When a small amount of an alkylated epoxide was added as a “kick‐start” accelerator to these same oxetanes, the redox initiated cationic polymerizations were extraordinarily rapid owing to the marked reduction in the induction period. A mechanistic interpretation of these results is offered. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1854–1861     

9-氯甲基蒽的实验室制备法

介绍一个在室温条件下反应制备9-氯甲基蒽——构造荧光分子探针的常用中间体的,方法。该实验以9-蒽甲醇和二氯亚砜为原料,苯为溶剂,在吡啶催化下反应,经水洗,干燥,旋转蒸发除去溶剂,最后得到固体产品。推荐该方法作为高校实验室自制9-氯甲基蒽的方法。     

Cationic ring-opening polymerization of 3,3-bis（chloromethyl）oxacyclobutane in ionic liquids

Cationic ring-opening polymerization of 3,3-bis(chloromethyl)oxacyclobutane catalyzed by BF_3·OEt_2 was carried out in ionic liquids [bmim]BF_4 and [bmim]PF_6.The influences of BCMO concentration and molar ratio of BCMO/BF_3·OEt_2 on the molecular weights and yield of PBCMO were investigated.The polymerization in ionic liquids proceed to high conversions,although molecular weights are limited,similar to polymerization in organic solvent such as CH_2Cl_2.Follow a viewpoint of green chemistry, we feel ionic liquid [bmim]BF_4 is superior to [bmim]PF_6.Extracting [bmim]PF_6 from the product using organic solvent as extractant limits its advantage as a green reaction media.     

Synthesis and transformations of acyloxy(chloromethyl)phosphonates and acyloxy(chloromethyl)phosphinates

The reactions ofO-phenyl chloromethylphosphonochloridate and bis(chloromethyl)phosphinous chloride with sodium acetate afford the corresponding acyloxyphosphonates and acyloxyphosphinates, which are readily transformed due to disproportionation into pyrophosphonates and pyrophosphinates. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp 2383–2385, November, 1998.     

On the two isomeric tris(perchlorothienyl)methyl radicals

The two isomeric tris(trichlorothienyl)carbinols have been synthesized. Upon treatment with acid the tris(trichlorothienyl)carbenium ions were formed, which upon reduction with iodide gave the tris(trichlorothienyl)methyl radicals, which were studied by epr-spectroscopy. The β-isomer, the tris(2,4,5-trichloro-3-thienyl)methyl radical, was much more stable than the α-isomer and showed great similarity to the perchlorotrityl radical.     

Coordinate anionic ring-opening polymerization of oxetanes with aluminum benzyl alcoholate bis(2,6-di-tert-butyl-4-methylphenolate)

Aluminum benzyl alcoholate bis(2,6-di-tert-butyl-4-methylphenolate) (BnOAD), which was prepared through the mixing of equimolar amounts of benzyl alcohol and methylaluminum bis(2,6-di-tert-butyl-4-methylphenolate) (MAD), successfully polymerized four-membered cyclic ethers in a coordinate anionic ring-opening manner. The polymerization of 3-(4-bromobutoxymethyl)-3-methyloxetane (OxBr) with 5 mol % BnOAD proceeded slowly in toluene at 25 °C and produced sufficiently high-molecular-weight poly(OxBr) in a moderate yield in 24 h. The polymerization was greatly accelerated by the addition of a sterically hindered Lewis acid such as MAD, and this resulted in a nearly quantitative polymer yield within 24 h. In sharp contrast, conventional cationic polymerization with boron trifluoride etherate as a typical Lewis acid initiator produced low-molecular-weight poly(OxBr) along with a substantial amount of the cyclic tetramer. The polymerization of the simplest unsubstituted oxetane with BnOAD resulted in failure. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4570–4579, 2004     

Tetrahydrofuran and 3,3-bis(chloromethyl) oxetane triblock copolymers synthesized by two-end living cationic polymerization

Triblock copolymers based on tetrahydrofuran (THF) and 3,3-bis(chloromethyl) oxetane (BCMO), BCMO-block-THF-block-BCMO and poly(BCMO-co-THF)-THF-(BCMO-co-THF), have been synthesized by two-end living cationic polymerization with a bifunctional initiator, trifluoromethanesulfonic anhydride [(CF₃SO₂)₂O]. The polymers are obtained by using the two end propagating species of poly(THF) to initiate the sequential BCMO polymerization. The resulting polymers are characterized by infrared (IR), nuclear magnetic resonance (NMR), and differential scanning calorimetry (DSC), confirming that the polymers are ABA-type block copolymers. The identities of the molecular weights predetermined and which determined by GPC show the success of predetermining molecular weights of the polymers and preparing well-defined polymers. The narrow polydispersities, 1.1–1.3, indicate that the chains are propagating by a living mechanism. © 1993 John Wiley & Sons, Inc.     

The role of solvent polarity and cocatalyst structure in the cationic polymerization of 3,3-bis(chloromethyl) oxetane

In the cationic polymerization of 3,3-bis(chloromethyl)oxetane induced by BF₃ the solvent polarity (toluene, methylene chloride, ethylene chloride, nitrobenzene, and nitromethane) does not influence the k_tr/k_p ratio, where k_tr stands for the rate constant of chain transfer to polymer. Increase of the overall polymerization rate is due mainly to the increase of k_i. The application of the steady-state conditions in which the slow formation of the active centers is compensated by the unimolecular chain transfer to polymer allowed the determination of k_tr/k_p ratios for several chain-transfer agents of low molecular weight. Alcohols and ethers of different basicities were used. It was established that the k_tr/k_p ratio is a linear function of ?pK_a of the chain-transfer agents.     

(Halomethyl)arsenic compounds : II. Preparation and dynamic NMR spectra of pentakis(chloromethyl)cyclopentaarsine

Hypophosphorous acid reduction of chloromethylarsonic acid produces the novel cyclopolyarsine, pentakis(chloromethyl)cyclopentaarsine (PCCA). PCCA possesses a greater thermal and oxidative stability than other cyclopolyarsines previously studied. The dynamic PMR properties of PCCA are interpreted as a combination of a low-energy limited pseudorotational motion and a higher-energy As-atom inversional process. An alternative to ground-state d-orbital participation in the interpretation of the electronic spectra is offered.     

4,5-Bis(chloromethyl)uracil

A one-step synthesis of 4,5-bis(chloromethyl)uracil from readily available starting materials has been accomplished. This substance is a stable, crystalline solid which undergoes facile nucleophilic attack to produce various di-substituted uracil derivatives.     

Preparation and polymerization of some N-(dialkylaminoalkyl)acrylamides

A series of N-(dialkylaminoalkyl)acrylamides was synthesized by reductive amination of N-(1,1-dimethyl-3-oxobutyl)acrylamide (diacetone acrylamide) and by the reaction of either an alkenylamine or an amino alcohol with acrylonitrile. These monomers homopolymerize and copolymerize readily to form high molecular weight products. The solubility of the monomers and their homopolymers in water ranges from soluble to insoluble at room temperature. The insoluble materials can be quaternized readily to produce water-soluble products. The solubility of the homopolymers in water decreases with increasing temperature. Glass transition and decomposition temperatures of the homopolymers are reported.     

Synthesis of bis (chloromethyl)chlorophosphine

Conclusions Synthesis of bis(chloromethyl)chlorophosphine is described.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 185–186, January, 1969.The authors wish to thank B.E. Ivanov and I.M Shermergorn for kindly supplying a sample of bis(chloromethyl) phosphoryl chloride.     

Solid-state polymerization of oxetanes. I. Lattice parameters and packing properties of the monomers

The crystallographic unit cells of melt-crystallized 3,3-bischloromethyloxetane and 3,3-bisbromomethyloxetane were determined by the Weissenberg method. The two isomorphous lattices are triclinic with two molecules in the unit cell. 3,3-Bisfluoromethyloxetane forms plastic crystals in the temperature range between ?36°C and +22°C, as shown by differential calorimetry and NMR broad-line spectroscopy. The Debye-Scherrer diagram and the general physical properties indicate the formation of a face-centered cubic lattice. No correlation between the lattice parameters of the monomer and polymer can be found On the basis of these results, the question is raised as to whether a topochemical polymerization of bishalomethloxetanes, i.e., a solid-state polymerization without destruction of the crystal lattice, can take place at all. The halomethyl side groups of the oxetanes can be shown to possess different conformations in monomer and polymer crystals, so that a conformational change of the groups and rearrangement of the molecules must take place during polymerization. Therefore, a topochemical mechanism for the solid-state polymerization of bishalomethyloxetanes seems to be impossible.     

Chain termination in polymerization of substituted oxetanes in the presence of boron trifluoride etherate

It has been shown that the polymerization of oxetanes with azidomethyl substituents initiated by boron trifluoride etherate in the absence and the presence of ethylene glycol proceeds via chain termination with fluorine atom transfer. This reaction results in the formation of a polymer that is monofunctional with respect to hydroxyl groups and contains a fluorine atom at one of the chain ends. With the use of ¹⁹F NMR spectroscopy, the number-average functionality of polymer with respect to fluorine atoms was studied. The methods of suppressing the aforementioned reaction, whose intensity decreases during a decrease in the polymerization temperature and an increase in the ethylene glycol concentration, were considered. In the absence of ethylene glycol, the chain termination with fluorine atom transfer is the main reaction of chain-propagation restriction.     

Tetrakis(chloromethyl)phosphonium chloride monohydrate

Tetrakis­(chloro­methyl)­phospho­nium chloride monohydrate, C₄H₈Cl₄P⁺·Cl^?·H₂O or P(CH₂Cl)₄⁺·Cl^?·H₂O, is the first crystal structure determination of a tetrakis­(halogeno­methyl)­phospho­nium compound to date. The only comparable structures known so far are of phospho­nium ions containing just one halogeno­methyl group. The solvent water mol­ecule interacts with the Cl^? anion via hydrogen bonds, with O?Cl distances of 3.230 (2) and 3.309 (2) Å. The structure also contains several C—H?Cl^? and C—H?O contacts, though with longer D?A distances [D?A 3.286 (3)–3.662 (2) Å] or bent D—H?A angles. For these reasons, the C—H?Cl^? and C—H?O interactions should not be considered as strong hydrogen bonds.     

Cerium(IV) ammonium nitrate-mediated oxidative rearrangement of cyclobutanes and oxetanes

A facile CAN-mediated oxidative rearrangement of alkoxyaryl cyclobutanes and oxetanes is described.     

Cu(I)-catalyzed oxidative cyclization of alkynyl oxiranes and oxetanes

In the presence of a Cu(I) catalyst and a pyridine oxide, alkynyl oxiranes and oxetanes can be converted into functionalized five- or six-membered α,β-unsaturated lactones or dihydrofuranaldehydes. This new oxidative cyclization is proposed to proceed via an unusual allenyloxypyridinium intermediate.